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Sedimentary geochemistry associated with the end-Triassic mass extinction: changes to the marine environment from an age constrained sedimentary section

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Sedimentary geochemistry associated with the end-Triassic mass extinction: changes to the marine environment from an age constrained sedimentary section

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Content Sedimentary geochemistry associated with the end-Triassic mass extinction: changes to
the marine environment from an age constrained sedimentary section
by
Joyce Ann Yager
_____________________________
A Dissertation Presented to the
FACULTY OF THE USC GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In partial Fulfillment of the
Requirements for the degree
DOCTOR OF PHILOSOPHY
(GEOLOGICAL SCIENCES)
August 2019
Acknowledgements

Financial support for this study came from the National Science Foundation and the
Elizabeth and Jerol Sonosky Fellowship, USC Earth Sciences, as well as the International
Association of Geochemists.

Thanks to Sean Lloyd, Kim Lau, Julio Sepulveda, Jessica Whiteside, and Paul Olsen for
discussion surrounding these chapters.

Judy Omura from the Los Angeles Natural History Museum and Will Berelson and Nick
Rollins from USC for modern sponge samples.

Laboratory assistance and facility use at USC from John Platt, Leo Xia, Seth John, Jim
Moffett, and Sergio Sanudo-Wilhelmy.

Thanks to Dave Janos, John Spear, Mark Patzkowsky, Steve Holland, and Robert
Garrison for their wisdom and good advice about science and life.

Thanks to collaborators on these and related projects Nick Rollins, Bridget Bergquist,
Aly Thibodeau, Manuel, Flavio Jodoul, Simona, Jo, Noah Planavsky, Kenn Williford,
Woodward Fischer, Elizabeth Trower, Tetsuji Onoue, Yunbin Guan, Michael Tuite,
Richard Behl, and Dave Selby.

All of the faculty and staff of the USC Earth Science department have been incredibly
supportive, but in addition to those advising me I would like to thank in particular Naomi
Levine, Sarah Feakins, Julien Emile-Geay, Seth John, Jim Moffett, Jan Amend, Sergio
Sanudo-Wilhelmy, David Okaya, and all of the amazing office staff: Vardui Ter-
Simonian, Cindy Waite, John McRaney, John Yu, Barbara Grubb, Miguel Rincon, and
Karen Young.

Renee Wang, Reyna Ibarra, Melissa Zepeda, and Debbie Sulca are warmly thanked for
field and lab help, and in particular Peter Wynn for being an incredibly big help in the lab
the last couple of years and enabling us to really increase how much we could do on this
project.

Silvia Rosas and Kathleen Ritterbush were extremely important in getting this project
started long before I arrived and were so supportive the entire time. Silvia’s knowledge of
Peru geology, in particular her knowledge of the Aramachay formation, and her generous
sharing of this information was instrumental to the success of this project.

It was an incredible privilege to occupy time in the lab, field, and classroom of four
wonderful faculty members from the USC department of earth sciences. Will Berelson,
Josh West, Frank Corsetti, Dave Bottjer, are so loved and thanked for their support and
encouragement for the last nearly 6 years. And of course for their unlimited guidance on
the project.

I have so much love and gratitude for friends who played such an outsized role in
supporting me the last six years. It feels absurd to reduce years of love and support to a
list of names that I’ll inevitably leave people off, but Cooper Harris, Marshall Rogers-
Martinez, Nate Carroll, Yubin Raut, Amanda Godbold, Claire Johnson, Paulina Pinedo-
Gonzalez, Hyejung Lee, Christine Mong Sin Wu, Sijia Dong, Kenny Bolster, Jessica
Stellmann, Sylvia Dee, Carlie Pietsch, Liz Petsios, Lydia Tackett, Yadi Ibarra, Sarah
Greene, Rowan Martindale, Hannah Liddy, Adam Holt, Willie Haskell, Gen Li, Danie
Monteverde Podocec, Ted Present, Nick Rollins, Megan O’Connor, Chris Evans, Kate
Murray, Timmy Willingham, Susie Cansler, Jordan Korn, Jillian Brenner, Jennifer Hall,
Pieter Share, Kirstin Washington, Erin McParland, Jeff Thompson, Dylan Wilmeth,
Olivia Piazza Paradis, Annie Tamalavage, Chelsea Rivera, Michelle Volk, Alex Hatem,
Mariah Landry, Ben Jassin, Emily Burt, Rachel Pausch, and Audra Bardsley, I could not
in any way have done this without you.
Thank you finally to my family, especially Amanda Yager, Brenda Seawell, and most
especially to my father David Yager for being unbelievably empathetic and encouraging
during this time.
This dissertation is dedicated to the memories of Jeff Schwarz, Sarah Anne Yager, and
Aileen Seawell Yager. They are loved and missed.
Table of Contents
Chapter 1: Introduction to the end-Triassic extinction and CAMP
magmatism ......................................................................................................1
1.1. OVERVIEW OF CAMP AND THE ETE ...........................................................1
1.1.1. Extinction patterns during the end-Triassic extinction ...............................2
1.1.2. CAMP and the ETE ........................................................................................4
1.2. GEOCHEMICAL INSIGHTS INTO THE TRIASSIC-JURASSIC
BOUNDARY ..................................................................................................................5
1.2.1. Carbon Isotopes ..............................................................................................5
1.2.2. Anoxia and the ETE .......................................................................................6
1.2.3. Proxies for CAMP in the sedimentary record ...............................................7
1.3. THE LEVANTO SECTION AS A KEYSTONE STRATIGRAPHIC
SECTION FOR UNDERSTANDING CHANGES DURING THE TRIASSIC-
JURASSIC BOUNDARY .............................................................................................8
1.3.1. Additional sites used in this study ...............................................................14
1.4. APPROACHES USED IN THIS STUDY ..........................................................14
1.4.1. Durations of C isotope changes ....................................................................16
1.4.2. Redox and biogeochemical change during the lead up and ETE .............16
1.4.3. Linking the ETE and CAMP magmatism: proxies for LIP magmatism in
the marine sedimentary record ..............................................................................17
1.4.4. First steps towards constraining the concentration of silicic acid in the
Mesozoic ocean ........................................................................................................17
REFERENCES .................................................................................................................20
Chapter 2: Duration of and decoupling between carbon isotope excursions
during the end-Triassic mass extinction and Central Atlantic magmatic
province emplacement ...................................................................................34
OPENING STATEMENT ...........................................................................................34
ABSTRACT ..................................................................................................................35
2.1. INTRODUCTION ...............................................................................................36
2.2. LEVANTO SECTION ........................................................................................37
2.3. METHODS ...........................................................................................................40
2.4. RESULTS .............................................................................................................42
2.4.1. δ
13
C
org
: isotope excursions and their durations ..........................................42
2.4.2. δ
13
C
carb
............................................................................................................45
2.4.3. %TOC and %CARB ....................................................................................45
2.4.4.Comparison of δ
13
C
org
, δ
13
C
carb
, %TOC, and %CARB records from
Levanto .....................................................................................................................45
2.5. DISCUSSION .......................................................................................................46
2.5.1. Assessing effects of diagenesis on the Levanto C isotope records ............46
2.5.2. Inorganic carbon isotopes: correlation and comparison with other sites 48
2.5.3. Organic carbon isotopes: correlation and comparison with other sites ..50
2.5.4. Offset in δ
13
C values between Tethys and Panthalassa .............................53
2.5.5. Decoupled carbonate and organic carbon isotope records during the Late
Triassic and Early Jurassic .....................................................................................54
2.5.6. Implications for timing of C cycle perturbation with respect to CAMP
magmatism ...............................................................................................................57
2.6. CONCLUSIONS ..................................................................................................59
REFERENCES .............................................................................................................60
2S. SUPPLEMENTAL INFORMATION FOR CHAPTER 2 .................................69
2S1. Sample collection and stratigraphic positioning ..........................................69
2S2. Sample processing and methods ....................................................................70
2S2.1. δ
13
C
org
and %TOC analyses .......................................................................70
2S2.2. δ
13
C
carb
and %TIC analyses ......................................................................72
References ................................................................................................................76

Chapter 3: Rising oxygen in the Late Triassic may have made the Earth
System more susceptible to perturbation before the end-Triassic extinction 79
OPENING STATEMENT ...........................................................................................79
ABSTRACT ..................................................................................................................80
3.1. INTRODUCTION ..............................................................................................81
3.2. LEVANTO SECTION AND SAMPLING .......................................................83
3.3. METHODS ..........................................................................................................85
3.4. RESULTS ............................................................................................................87
3.4.1. Nitrogen isotope and C:N ratios ..................................................................87
3.4.2. Trace metal concentrations ..........................................................................87
3.5. DISCUSSION ......................................................................................................90
3.5.1. Orbitally-forced cyclicity in δ
15
N at the Levanto section during the Late
Triassic .....................................................................................................................90
3.5.2. Increasing ocean oygenation in the lead up to the end-Triassic extinction
....................................................................................................................................92
3.5.3. A modern style nitrogen cycle during the Late Triassic ...........................96
3.5.4. Rapid drop in oxygen: Onset of loca marine euxinia at the time of
extinction and globally pervasive anoxia that follows ..........................................97
3.5.5. Cessation of anoxia at ~200.8 Ma ................................................................99
3.5.6. Increasing oxygenation increases perturbation susceptibility ..................99
3.5.7. CAMP and the ETE .....................................................................................101
3.6. CONCLUSIONS ...............................................................................................103
REFERENCES ...........................................................................................................105
3S. SUPPLEMENTAL INFORMATION FOR CHAPTER 3 ...............................116
3S1. The marine N cycle and isotopic fractionation ..........................................116
3S2. Alternative explanations for a Rhaetian shift in sedimentary δ
15
N at
Levanto ...................................................................................................................118
3S2.1. Shift in proportion of sedimentary denitrification ................................118
3S2.2. Shift in nitrate utilization .......................................................................118
3S2.3. Shift towards nitrogen-fixation dominated community ........................119
3S3. Diagenetic, depositional environment, and oxygen exposure time ...........120
3S3.1. Changes in marine and continental-derived fractions ...........................120
3S3.2. Changes in bottom water oxygenation and their diagenetic effects on
δ
15
N .........................................................................................................................121
3S3.3. Changes in δ
15
N during sinking and remineralization ..........................123
3S4. Detrital fraction and potential dilution of trace metals ............................124
References ...............................................................................................................130

Chapter 4: Depositional environment controls the expression of Mercury
concentration and isotope anomalies associated with Large Igneous Province
Magmatism and the end-Triassic extinction ...............................................133
OPENING STATEMENT .........................................................................................133
ABSTRACT ................................................................................................................134
4.1. INTRODUCTION ............................................................................................135
4.2. OVERVIEW OF LOCALITIES .....................................................................139
4.2.1. New York Canyon, Nevada ..........................................................................139
4.2.2. St. Audrie’s Bay, UK ....................................................................................141
4.2.3. Levanto, Peru ................................................................................................142
4.3. MATERIALS AND METHODS .....................................................................144
4.3.1. Sample processing ........................................................................................144
4.3.2. Hg concentrations .........................................................................................144
4.3.3. Hg isotope measurements ............................................................................145
4.3.4. %TOC and %TIC .........................................................................................146
4.4. RESULTS ..........................................................................................................147
4.4.1. New York Canyon .........................................................................................148
4.4.2. St. Audrie’s Bay ...........................................................................................150
4.4.3. Levanto ..........................................................................................................150
4.4.4. Consistencies between sections ....................................................................155
4.5. DISCUSSION ....................................................................................................155
4.5.1. Lithologic controls on Hg/TOC ...................................................................155
4.5.2. Depositional setting and Hg isotopes ..........................................................160
4.5.3. Implications for applying Hg concentrations and isotopes as a proxy for
magmatism in the sedimentary record ...................................................................161
4.6. CONCLUSIONS ...............................................................................................163
REFERENCES ...........................................................................................................160

Chapter 5: Silicon isotopes in sponge spicules suggest low dissolved silica
during the mid-Mesozoic and drawdown by sponges in aftermath of end-
Triassic extinction
OPENING STATEMENT ........................................................................................171
ABSTRACT ................................................................................................................172
5.1. INTRODUCTION ............................................................................................173
5.2. STRATIGRAPHIC SECTIONS AND SAMPLES ........................................177
5.2.1. Levanto, Peru ................................................................................................178
5.2.2. Malpaso (Central Peru) ...............................................................................179
5.3. METHODS ........................................................................................................180
5.3.1. Sample preparation ......................................................................................180
5.3.2. SIMS analyses ...............................................................................................181
4.3.3. Data reduction ..............................................................................................182
5.4. RESULTS ..........................................................................................................182
5.4.1. Modern sponge spicule δ
30
Si .......................................................................182
5.4.2. Mesozoic sponge spicule δ
30
Si .....................................................................184
5.5. DISCUSSION ....................................................................................................186
5.5.1. Low marine silica concentrations during the Triassic-Jurassic Boundary
..................................................................................................................................186
5.5.2. Changes in the marine silica cycle in the aftermath of extinction across the
Triassic-Jurassic Boundary ...................................................................................186
5.6. CONCLUSIONS ...............................................................................................188
REFERENCES ...........................................................................................................190
5S: SUPPLEMENTAL INFORMATION FOR CHAPTER 5 ..............................198
5S1. Spicule preservation types and SIMS analysis sorting .................................198
3S2. Raman spectroscopy ......................................................................................199

Chapter 6: Conclusions ...............................................................................207
6.1. A SYNTHESIS OF LEVANTO SECTION DATA AND
INTERPRETATIONS ..........................................................................................207
6.1.1. Linking the Levanto section and end-Triassic extinction to the modern
..............................................................................................................................207
6.1.2. The potential role of basin restriction at the Levanto section ............208
6.1.3. Next steps and future avenues ...............................................................209
6.1.3.1. Decoupled C isotope records across the Triassic-Jurassic
boundary? ....................................................................................................211
REFERENCES .......................................................................................................209

Appendix A: Overview thin section photomicrographs from the Levanto
section .........................................................................................................215
A.1. IMAGES ........................................................................................................215
A.2. THIN SECTION CATEGORY DESIGNATIONS ....................................246
Appendix B: Inconclusive osmium isotopes from the Levanto section ......248
B.1. OSMIUM AS A POTENTIAL TRACER OF CAMP MAGMATISM ....248
B.2. PREVIOUS OSMIUM WORK ACROSS THE TJB .................................249
B.3. PRELIMINARY OSMIUM ISOTOPES FROM THE LEVANTO
SECTION ..............................................................................................................250
REFERENCES ......................................................................................................255
B.4. OSMIUM ISOTOPE DATASET .................................................................256
Appendix C: Rock eval data from ten Levanto samples .............................257
Appendix D: Outcrop weathering and sedimentary geochemistry .............265
Appendix E: SEM/EDS imaging of a sample from the Levanto section
highlight the presence of P ..........................................................................269
E.1. EDS AND SEM MAPPING ..........................................................................269
Appendix F: Hg and S are associated in a sample from Kennecott Point ..272
REFERENCES ......................................................................................................277
Appendix G: C isotope and concentration data from Levanto, Peru (dataset
from Chapter 2) ...........................................................................................278
Appendix H: Nitrogen isotope and trace metal concentration data (dataset
from Chapter 3) ...........................................................................................282
H.1. LEVANTO, PERU ........................................................................................282
Table 3.1. Correlation coefficients for data in Appendix H1 .........................287
H.2. NEW YORK CANYON, NEVADA ............................................................288
Appendix I: Mercury concentration and isotope data (dataset from Chapter
4) ..................................................................................................................289
I.1. MERCURY AND CARBON CONCENTRATION DATA ........................289
I.1.1. Levanto, Peru ...........................................................................................289
I.1.2. St. Audrie’s Bay, UK ...............................................................................296
I.1.3. New York Canyon, Nevada ....................................................................299
I.2. MERCURY ISOTOPE MEASUREMENTS ...............................................302
I.2.1. Levanto, Peru ...........................................................................................302
I.2.2. St. Audrie’s Bay, UK .................................................................................... 304
I.3. MERCURY ISOTOPE STANDARDS .........................................................306
Appendix J: Sponge spicule silicon isotope data (dataset from Chapter 5) 308
J.1. LEVANTO, PERU .........................................................................................308
J.2. MALPASO, PERU .........................................................................................317

Chapter 1: Introduction to the end-Triassic extinction and
CAMP magmatism
1.1. OVERVIEW OF CAMP AND THE ETE
Current anthropogenic atmospheric CO
2
input threatens to perturb the climate and
biosphere, and a sixth mass extinction is underway (e.g. Ceballos et al., 2015; IPCC
2014). Several times in Earth’s history, dramatic environmental change coincided with
mass extinctions (see Bond and Wignall, 2014 for a review). Like the modern situation,
the end-Triassic mass extinction—one of the “big 5” mass extinctions of the Phanerozoic
(e.g. Alroy 2010) —was associated with dramatic CO
2
rise (e.g. Schaller et al., 2011;
Schaller et al., 2012; McElwain et al., 1999; McElwain et al., 2005; Steinthorsdittir et al.,
2012). The end-Triassic mass extinction was the greatest loss of diversity of the so-
called modern fauna in Earth’s history (Sepkoski 1981; Fig. 1). The Central Atlantic
Magmatic Province (CAMP), a large igneous province (LIP) associated with the breakup
of Pangea, has been linked to the mass extinction via emission of volatiles (e.g. CO
2
,
SO
2
) with strong climatic and environmental forcing (e.g., Marzoli et al., 1999; Ward et
al., 2001; McHone 2003; Guex et al., 2004; Hesselbo et al., 2002; Hesselbo et al., 2004;
Guex et al., 2016). Understanding the causes of extinction during the Late Triassic and
their association with CAMP volatiles aids in understanding major changes to the Earth
System during time of major perturbation, i.e. under rapidly increasing CO
2
and the
corresponding cascade

of effects (e.g. Self et al., 2014).
1

1.1.1. Extinction patterns during the end-Triassic extinction
The end-Triassic extinction was particularly severe for the so-called “modern”
evolutionary fauna, marine animals similar to those that live today like corals, clams, and
bivalves (e.g. Alroy 2010; Sepkoski 1981; Fig 1). Scleractinian coral reefs experienced
their most severe crisis of the Mesozoic during the ETE (Flügel, 2002; Flüegel and
Kiessling, 2002; Martindale et al., 2012) and bivalves and ammonoids also suffered
major extinctions (Hallam 2002). Plant macrofossils experienced an 85% species loss
(McElwain et al., 1999; McElwain et al., 2009) and major palynological turnover
occurred (e.g. Lindstrom et al. 2014).
Ocean acidification, resulting from increased CO
2
input, likely perturbed marine
carbonate producers in particular (Greene et al., 2012; Martindale et al., 2012; Hodges et
al., 2015), while widespread ocean anoxia likely prolonged the recovery stage. A major
!"#$%&'()
*+#,$-%./%0 $1$-(
!" # $ % ! &' ( ) * + ', -,
. /.. 0.. 1.. 2.. 3..
. /.. 0.. 1.. 2.. 3..
'.2$-1
3 (4$.5."6
7(#,-"(1
Figure 1.
Phanerozoic
diversity
trends, with
largest decline
of modern
fauna during
end-Triassic
extinction
(Alroy 2010).
2
ammonite extinction occurs during the ETE (Guex et al. 2004; Guex et al. 2012; Guex et
al. 2016) and benthic carbonate producers did not recover for approximately 1.5 million
years (Greene et al., 2012; Martindale et al., 2015; Ritterbush et al., 2014; Ritterbush et
al., 2015; Corsetti et al., 2015). Shallow benthic siliceous sponges occupied the shallow
benthic environment during the early recovery, apparently taking advantage of carbonate
producer displacement or increased silicic acid (Ritterbush et al., 2014; 2015).

3
1.1.2. CAMP and the ETE
CAMP is estimated to have extended over an area 1.1 x 10
7
km
2
and was 2.4 x
10
6
km
3
by volume (McHone et al., 2003), covering a substantial portion of Pangea as it
began to rift (Fig. 2). CAMP released atmospheric CO
2
, which led to an estimated
quadrupling of CO
2
(McElwain et al., 1999) and an increase of 3-6ºC globally (Beerling
and Berner, 2002; Huynh and Poulsen, 2005). Recent U-Pb zircon dating from North
American CAMP basalts yield an earliest age of 201.56 Ma and latest age of 200.9 Ma
for CAMP, and the end-Triassic extinction occurred at 201.5 Ma, clearly linking the
extinction with CAMP emplacement in North America (Blackburn et al., 2013; Guex et
al., 2012; Davies et al., 2017; Marzoli et al., 1999). Increased mercury concentrations in
the marine sedimentary record, which are a proxy for volcanism, coincide with the
extinction interval and earliest recovery stage following the end-Triassic extinction
(Thibodeau et al., 2016; Percival et al. 2017). This record overlaps temporally with U-Pb
CAMP dates. However,
40
Ar/
39
Ar ages yield a much broader range in age, from
202.8±1.8 to 195±2.1 with a peak at 201.4±.9 Ma (Marzoli et al., 2011; Nomade et al.,
2007) and tracers of mantle input and weathering (
187
Os/
188
Os;
87
Sr/
86
Sr) across the
Triassic-Jurassic boundary (TJB) suggest CAMP emplacement may have begun early in
the Rhaetian (Kuroda et al., 2010) and that enhanced weathering may have begun in the
latest Rhaetian (Cohen and Coe, 2007; Kuroda et al., 2010; Fig 2). Nomade et al., (2007)
suggest intrusive CAMP volcanism began ~202 Ma, and suggest extrusive volcanism
began abruptly ~200 Ma. This difference between intrusive and extrusive CAMP
volcanics could be the source for such variable CAMP onset estimates. Overall, CAMP
4
ages do not directly coincide with best-known evidence for CAMP in the marine
sedimentary record.

1.2. GEOCHEMICAL INSIGHTS INTO THE TRIASSIC-JURASSIC
BOUNDARY
1.2.1. Carbon Isotopes
A negative shift in organic carbon isotopes is observed coincident with the
extinction interval in many studied stratigraphic sections spanning the TJB (e.g. Ward et
al., 2001; Palfy et al., 2001; Hesselbo et al., 2002; Guex et al., 2004; Ward et al., 2007;
Ward et al., 2004; Bachan et al., 2012; Lindstrom et al., 2012). The presence of the
negative shift in organic carbon isotopes has therefore been hypothesized as an indication
of CAMP-derived carbon cycle perturbation. However, the proposed mechanism for this
shift and its hypothesized relationship with the extinction vary widely. Hypotheses
include CAMP CO
2
emission and global warming (e.g. Hesselbo et al., 2002; Beerling
and Berner, 2007), SO
2
emissions and global cooling (Guex et al., 2004; Schoene et al.,
2010; Guex et al., 2016), ocean acidification via atmospheric CO
2
input (see Greene et
al., 2012 for a review), and changes in nutrient supply via increased weathering from
increased atmospheric CO
2
, resulting in eutrophication and potential decreased
oxygenation in water (e.g. van de Schootbrugge et al., 2007; Lindstrom et al., 2012).
Their global nature and likely atmospheric forcing (e.g. compound specific C isotopes
from Ruhl et al., 2011) make these shifts in C isotopes important for modeling studies
seeking to understand their causes. However, changes to the global carbon cycle during
the end-Triassic and Early Jurassic are poorly constrained with respect to timing and
5
relation to CAMP emplacement and the mass extinction. Prior age constraints on the
duration of excursions are estimated from cyclicity and vary widely (Ruhl et al. 2010) but
attaining a better age constraint for each C isotope shift is vital for future modeling
studies to better understand C cycle changes (e.g. Bachan et al., 2015).

1.2.2. Anoxia and the ETE
During LIP magmatism at many hyperthermal intervals in Earth’s history,
including the TJB, CO
2
release is hypothesized to trigger ocean anoxia due to increased
temperatures (and less oxygen dissolution in water), and because of resulting weathering
feedback and delivery of P, which initiates eutrophication, as well as the warming
temperatures slowing ocean circulation and turnover (e.g. van de Schootbrugge et al.,
2013). Black shale deposition in Tethys was widespread during the Early Jurassic (e.g.
van de Schootbrugge et al., 2013), likely due to the CO
2
eutrophication feedback. In
Panthalassa, photic zone euxinia has been seen from the Kennecott Point section
(Kasprak et al., 2015) and U isotopes suggest a 40-100 fold increase in anoxic deposition
during the Early Jurassic (Jost et al., 2017). Trace metal and nitrogen isotopes from
Tethys (Quan et al., 2008; Paris et al., 2010) suggest low oxygen during the Early
Jurassic. Some have also suggested low N availability in Panthalassa from nitrogen
isotopes (Schopefer et al., 2016). One outstanding question is why black shale deposition
is predominantly restricted to Tethys in the Early Jurassic, since many ‘ocean anoxic
events’ coincide with mass extinction in deep time and sedimentologically, the ETE
presents less anoxic sediments (Jenkyns et al., 2010). Additionally, little information is
available about the redox state prior to the ETE, and CAMP mamgmatism may have
6
started earlier in the Rhaetian (see next section), possibly affecting the Late Triassic
redox state of the oceans.

1.2.3. Proxies for CAMP in the sedimentary record
In addition to the robust age dating of CAMP basalts, proxies for CAMP and LIP
deposition in the sedimentary record offer a record of CAMP within the same record of
extinction. Osmium isotopes from St. Audrie’s Bay and Japan (Kuroda et al., 2010;
Cohen and Coe, 2007) suggest increasing mantle input during much of the Late Triassic
with a subsequent increase in radiogenic, or weathering-derived material during the ETE
and early Jurassic. This hints that CAMP may have occurred before the time indicated by
currently available CAMP U-Pb ages. However, constraining the ages of the Japanese
record in particular is difficult, as the section is condensed and lacks ammonites or ash
beds to correlate with other sections, and an outstanding question is when mantle derived
and weathering derived material began to dominate the osmium system.
Hg concentrations and isotopes are also a proxy for LIP magmatism (e.g. Sial et
al., 2014; Sanei et al., 2011; Percival et al., 2015; Grasby et al., 2016; Font et al., 2016),
and have been used to fingerprint CAMP in the sedimentary record (Thibodeau et al.,
2016; Percival et al., 2017), since Hg comes from volcanoes and can be globally
distributed (Pyle and Mather, 2003). However, the Hg proxy does not always record LIP
activity at each section (e.g. Percival et al., 2018) and may be affected by local effects
and the style of magmatism (e.g. intrusive vs extrusive; aerial vs subaerial; Percival et al.,
2018). At the ETE, a direct, temporally constrained link between the record of extinction
and environmental change and CAMP magmatism is still elusive, and major questions
7
about differences in Hg concentrations and isotopes in different depositional settings
complicate the Hg proxy.
In summary, outstanding questions from geochemistry spanning the Triassic-Jurassic
boundary include:
1. What was the duration and cause of C isotope excursions? To what extent do the
isotope excursions reflect changes in the C cycle, and how were these changes
related to the extinction (both temporally and causally)?
2. What role did anoxia and euxinia play in the extinction and its aftermath?
3. What was the duration of CAMP magmatism and did it begin earlier than CAMP
U-Pb ages suggest (e.g. Kuroda et al., 2010)?
4. What other biogeochemical changes occurred in the leadup, during, and after
extinction, and how did these changes relate to CAMP and to biotic turnover?
5. Does the extinction interval represent a warming event (e.g. Schaller et al., 2014)
or a cooling event (e.g. Guex et al. 2016)?
6. Are records of Hg concentrations a reliable record of CAMP in the marine
sedimentary record?

1.3. THE LEVANTO SECTION AS A KYESTONE STRATIGRAPHIC SECTION
FOR UNDERSTANDING CHANGES DURING THE TRIASSIC-JURASSIC
BOUNDARY
Linking the ETE and CAMP requires robust age constraints. A stratigraphic
section in Northern Peru near the town of Levanto, which here we call the Levanto
section, contains hundreds of ash beds intercalated with carbonate-rich mudstones and
8
provides the unequivocal temporal link between CAMP and the ETE. U-Pb age dating of
zircons from several of these ash beds, coupled with ammonite biostratigraphy, yielded
the durations of the Rhaetian and Hettangian, precise age date of the ETE and Triassic-
Jurassic Boundary (Schaltegger et al., 2008; Wotzlaw et al., 2014; Schoene et al., 2010;
Guex et al., 2012), and a potential framework to conduct high resolution, age constrained
sedimentary geochemistry (this study). In addition to the robust age constraints, the
Levanto section also was deposited well below storm wave base, and underwent minimal
depositional change during the ~4 million year continuous section, making it well suited
for generating geochemical records that are not dominated by facies change. Although
hydrothermal alteration may be of concern in Central Peruvian sections spanning the
Triassic-Jurassic boundary, Rock Eval (see appendix C) does not suggest high
temperature thermal alteration at Levanto, and no large veins are observed that indicate
hydrothermal alteration. We therefore speculate hydrothermal alteration plays a minimal
role in any proxy records from Levanto.
The Levanto section is part of a large swath of Mesozoic sediments deposited in
the Pucará basin, which spans much of the Central Peruvian Cordillera (Rosas et al.,
2007; Fig 3). At the Levanto section, the entire road cut outcrops as Aramachay
Formation (Fig 4). Nearby sections first outlined by von Hillebrandt (1994) were sampled
as potential shallower compliments to the Levanto section, but did not yield the same
broad and geochemically viable outcrops that are needed for geochemistry (discussed
further in Fig 5). In Central Peru (e.g. Ritterbush et al., 2015; 2014), ca. 600 km south of
Levanto, carbonate and dolomite span the Triassic-Jurassic boundary and record
shallower successions across the TJB. The Chambará Formation typically spans the
9
Norian and Rhaetian, the Aramachay Formation typically spans the Rhaetian-Sinemurian,
and the Condorsinga Formation typically begins in the Toarcian (Rosas et al. 2007).
These Central Peruvian sections are important in mining operations: they preserve
siliceous sponges in the shallow benthic environment, deposits of which may have
functioned as a cap for migrating fluids, making them an essential component in
understanding the origin of Central Peruvian mineral resources.

The central Peruvian sections are extensively documented by Rosas et al. (1994;
1995; 1996; 1997; 2007), with early ammonite biostratigraphy in the region by von
Hillebrandt (1973). Guex et al. (2012) conducted high-resolution ammonite
biostratigraphy at the Levanto section, placing it in a robust biostratigraphic framework.
Together, the Peruvian TJB sections include the best age-constrained section which is
o 0 7 o 5 7 o 0 8
5 o
10 o
15 o
Lima
0 250 km
ECUADOR
BRAZIL
BOLIVIA
Pucara Group
Levanto
Malpaso
Figure 3. Map of
Peru and the Pucará
group, with Levanto
and Malpaso (Central
Peru) site from
Ritterbush et al.
(2015).
10
!"#$% &',)'9 'EL+H%-#$/'+5733+'7/*&'E+E"'/'A+H'2%&+3%5/L+6%/%&.+>8M+'5+/"%+H%-#$/'+.%*/)'$A+N'/%+'&#$4%+#."+
J%,.A+H'2%&+&)4"/L+6%/%&+O>+'5+/"%+H%-#$/'+.%*/)'$1+$'/%+&%.)./ #$/+3#0%&+;6%/%&+./)*P@+#$,+5&0#J3%1+/")$+J%,,%,+
3#0%&+#J'-%A+
Figure 4. Top: Levanto full outcrop photo. Lower left: meters 0-3 of the Levanto section. Note
orange ash beds. Lower right: meter 60 of the Levanto section. Note resistant layer (meter stick)
and fryable, thin-bedded layer above.
11
!"#$% &'-)'-'$+Q)33%J&#$,/+;?RRS@+&%E'&/%,+#66'$)/%.+5&'6+.%-%+.)/%.+#3 '$4+/"%+FT'+U/*76J#6J#1+
)$*37,)$4+$%#&+/"%+H%-#$/'+.%*/)'$A+V'6%+'5+/"%.%+.)/%.+'7/*& 'E+#.+."#33'2%&+E'&/)'$.+'5+/"%+.#6%+J#.)$+#.+
/"%+H%-#$/'+.%*/)'$1+#$,+2%+#//%6E/%,+/'+5)$,+/"%6+#.+/"%0+2'73 ,+J%+#$+%:*%33%$/+*'6E3)6%$/+/'+/"%+,%%E%&+
2#/%&+.%*/)'$A+ W %+#//%6E/%,+/'+5)$,+/"%+'7/*&'E+$%#&+V7/#+;Q)33%J&#$,/+?RRS@+#$,+6#0+"#-%+5'7$,+#+E'&/)'$+
'5+/"%+'7/*&'E+;/'E+3%5/@X+"'2%-%& 1+)/+.%%6%,+3)P%+#+"'7.%+2#.+J7)3/+'$+/'E+'5+2"%&%+/"%+'7/*&'E+2#.+;/'E+
&)4"/@+.'+2%+,),+$'/+/#P%+6'&%+/"#$+#+E&%3)6)$#&0+.#6E3%A+ W %+#3.'+#//%6E/%,+/'+5)$,+/"%+.%*/)'$+$%#&+B")3)$ 8
4'/%+;Q)33%J&#$,/+?RRS@+#$,+6#0+"#-%+5'7$,+/"%+&)4"/+'7/*& 'E1+J7/+/"%&%+2#.+3)6)/%,+%:E'.7&%+#$,+/"%+&'*P.+
.%%6%,+/'+J%+)$+E''&+*'$,)/)'$+#$,+)$$#E&'E&)#/%+5'&+.%,)6%$/#&0+4%'*"%6)./&0+;J'//'6@A+++
>AK+6%/%&.
?+6%/%&
12
!"#$% &'.)'V/A+ <7,&)%Y .+Z#0+.%*/)'$A+
Figure 5 (previous page). von Hillebrandt (1994) reported ammonites from several sites along
the Río Utcumbamba, including near the Levanto section. Some of these sites outcrop as shal-
lower portions of the same basin as the Levanto section, and we attempted to find them as they
would be an excellent compliment to the deeper water section. We attempted to find the outcrop
near Suta (Hillebrandt 1994) and may have found a portion of the outcrop (top left); however, it
seemed like a house was built on top of where the outcrop was (top right) so we did not take
more than a preliminary sample. We also attempted to find the section near Chilingote (Hille-
brandt 1994) and may have found the right outcrop, but there was limited exposure and the
rocks seemed to be in poor condition and innapropriate for sedimentary geochemistry (bottom).
13
globally corellable with ammonite biostratigraphy (the Levanto section) and many
expanded, carbonate and silicia rich shallow benthic sections comparable to the
depositional environment seen at many other TJB localities (Central Peruvian sections).

1.3.1. Additional sites used in this study
I also sampled additional sites for comparison, including the Ferguson Hill section
from the New York Canyon area of Nevada and St. Audrie’s Bay, UK. St. Audrie’s Bay
(Fig 6) represents one of the longest-studied TJB sections (e.g. Mayall et al., 1981;
Hesselbo et al., 2004; Warrington et al., 1994). New York Canyon, Nevada is the best-
studied Panthalassic section spanning the TJB (e.g. Taylor et al., 1983; Taylor and Guex,
2002; Lucas and Tanner, 2007; Fig 7). Both sections are discussed further in Chapter 4.

1.4. APPROACHES USED IN THIS STUDY
Each proxy used in sedimentary geochemistry has unique propensities for
preservation in different lithologies. Depositional environment and diagenesis may play
major roles in the final outcome of each proxy, and for each system (e.g., O isotopes, C
isotopes, S isotopes, Hg and other metal concentrations and isotopes, etc.) the ‘best’ case
scenario for understanding global changes to a system is different. For example, in the S
cycle, which couples with the C cycle on geologic time and plays an important role in
balancing CO
2
emissions and weathering, S isotopes may offer information about the
global S cycle through time. However, unlike systems such as C and O, which are best
measured away from shallow facies (e.g. dolomitized limestones deposited in shallow
lagoons, e.g. Swart et al. 2011; Ohlert et al. 2012; Ohlert and Swart 2014), S isotopes
14

record the S cycle most reliably in shallow facies, and not in deep facies (Present et al.
2015), and so S isotopes are not well suited to sites like the Levanto section. To provide
the context for interpreting the new geochemical records presented from Levanto, I report
‘overview images’, or photomicrographs at 25x and plane polarized light, representative
of each sample (if available) in Appendix A. In this study, when possible, I paired any
geochemical measurement with a thin section and microscopy observations to provide
additional constraints on the depositional environment and diagenetic history of that
sample.
For example, in Chapter 2, I found no relationship between lithology and organic
C isotope value. However, in four samples with anomalous inorganic C isotope values, I
!"#$% &')' N%2+ '&P+B#$0'$+#&%#+'5+N%-#,#1+%& 47.'$+Q)33+.%*/)'$A+
Figure 7. New York Canyon area of Nevada, Ferguson Hill section.
15
found recrystallized diagenetic carbonate, which likely explains the anomalous C isotope
values for those samples. In Chapter 4, I use thin section images to demonstrate the
differences seen in Hg concentrations from compacted and uncompacted beds, which
play a major role in Hg/TOC and cannot be seen in hand sample.

1.4.1. Durations of C isotope changes
In Chapter 2 (Yager et al., 2017), I address the major outstanding question
regarding the durations of C isotope changes across the Triassic-Jurassic boundary in a
high-resolution study of C isotopes from the Levanto section. I find decoupled organic
and inorganic carbon isotope records from the Levanto section, which closely resemble
existing records from Italy (Bachan et al., 2012). A protracted positive shift in inorganic
C isotopes suggests C cycle change occurs well before (>2 Ma) the ETE, and raises the
question: what other changes in addition to the C cycle are occurring during the lead up
to the ETE?

1.4.2. Redox and biogeochemical change during the lead up and ETE
In Chapter 3, we attempt to further uncover what changes preceded the ETE by
employing stable nitrogen isotopes and trace metal concentrations as proxies for regional
and global changes in redox-linked biogeochemistry. We find evidence for increasing
oxygenation during the Late Triassic, which may have made the Earth system more
susceptible to perturbation during CAMP emplacement and volatile release.

16
1.4.3. Linking the ETE and CAMP magmatism: proxies for LIP magmatism in the
marine sedimentary record
In Chapter 4, I use Hg concentrations and isotopes from the Levanto section and
from the New York Canyon, Nevada, Ferguson Hill section and the St. Audrie’s Bay, UK
section as a proxy for fingerprinting CAMP magmatism in the marine sedimentary
record. CAMP U-Pb ages do not coincide with well-constrained Hg anomalies from
Levanto. In all three study sections, some aspect of depositional environment seems to
control Hg and Hg/TOC, but during the ETE and CAMP emplacement at all three
sections, a volcanically-derived Hg isotope signature is found in MIF isotopes of Hg. We
also measured preliminary osmium isotopes from the Levanto section, since these also
offer a proxy for CAMP emplacement that may not be impacted by the same lithologic
changes within a robust chronological framework and in an organic-rich setting,
presumably very appropriate for osmium isotopes (e.g. Selby and Creaser, 2003; Ravizza
and Turekian, 1992). However, we found the initial osmium isotopes extremely
anomalous at the Levanto section with respect to our understanding of the osmium
isotope system, and discuss possible reasons and interpretations for these surprising
preliminary results in Appendix B.

1.4.4. First steps towards constraining the concentration of silicic acid in the
Mesozoic ocean
During the Early Jurassic, shallow benthic sponges replaced carbonate producers
in shallow ramp environments (Ritterbush et al., 2015; Ritterbush et al., 2014). This
prolonged occupancy of sponges in the shallow environment may suggest high silicic
17
acid concentrations in the ocean, which sponges may have exploited given its abundance.
Ritterbush et al. (2015) suggested CAMP may have delivered enough CO
2
to increase
weathering and silicic acid feedback, and CAMP basalts may have provided a silica
source as well. However, Alvarez et al. (2017) noted that silica concentrations do not
correlate with sponge abundance in the modern ocean, and so increased silica
concentrations may not be the primary driver of sponge reef dominance during the Early
Jurassic. The Mesozoic silica cycle is poorly constrained, and is assumed to be orders of
magnitude higher than current concentrations due to the absence of diatom fossils and
abundance of chert in the rock record. The concentration of silica remains a major
outstanding question for the entire Mesozoic silica cycle, and one that is inextricably
linked to the carbon cycle by C burial and nutrient utilization. In Chapter 5, I report the
first mid-Mesozoic sponge spicule silicon isotope measurements, which are a proxy for
silicic acid concentrations (e.g. Hendry et al., 2010; Wille et al., 2010; Hendry and
Robinson, 2012), providing the first semi-quantitative estimates of silica concentrations
before the Paleogene.
Additionally, I discuss next steps, including future biomarker and compound
specific C isotope work, which may help elucidate causes of the C cycle perturbations in
Chapter 6. Levanto samples are appropriate for organic geochemistry based on
preliminary rock eval assessment (Appendix C). We also address the weathered nature of
the Levanto outcrop, which like any outcrop from the Triassic-Jurassic boundary, has
experienced some surficial oxidation. We explore the effect surficial weathering has on
some of the proxies measured here in Appendix D. Finally, we address the potential role
of P in Appendix E as a major missing component of our understanding of the nutrient
18
cycle at the Levanto section. I also report the potential association of S and Hg in marine
sedimentary rocks in Appendix F.
19
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33
Chapter 2. Duration of and decoupling between carbon
isotope excursions during the end-Triassic mass extinction
and Central Atlantic magmatic province emplacement

OPENING STATEMENT
In Chapter 1, I discussed the importance of understanding the timing of C cycle
changes associated with the ETE. In particular, the timing of the negative isotope
excursion that coincides with the ETE has remained unconstrained and has hampered
modeling of the C cycle perturbation associated with this excursion. Here, we report high
resolution, age constrained C isotope record from the Triassic-Jurassic boundary section
near Levanto, which records decoupled C isotopes in organic and inorganic carbon.
Inorganic C isotopes change for most of the four million year record, including during the
~2.5 Ma before the ETE, and thus generating interest during the lead up to the end-
Triassic extinction and its potential link to CAMP magmatism.
Silvia Rosas, Josh West and I sampled the Levanto section in December, 2014. I
cut, crushed, decarbonated and dissolved the samples in this study and ran them on the
Picarro in Will Berelson’s lab at the University of Southern California with much help
and support from Nick Rollins. I analyzed the data, plotted and made the figures, and
wrote the paper. Josh West, Will Berelson, Dave Bottjer, Frank Corsetti, Silvia Rosas,
and Nick Rollins all helped write the paper.

This paper was published as:
34
Yager, J. A., West, A. J., Corsetti, F., Berelson, W. M., Rollins, N. E., Rosas, S, Bottjer,
D. J., 2017, Duration of and decoupling between carbon isotope excursions during the
end-Triassic mass extinction and Central Atlantic Magmatic Province emplacement.
Earth Planet. Sci. Lett. v. 473, p. 227-236; doi: 10.1016/j.epsl.2017.05.031.

ABSTRACT
Changes in δ
13
C
carb
and δ
13
C
org
from marine strata occur globally in association
with the end-Triassic mass extinction and the emplacement of the Central Atlantic
Magmatic Province (CAMP) during the break up of Pangea. As is typical in deep time,
the timing and duration of these isotopic excursions has remained elusive, hampering
attempts to link carbon cycle perturbations to specific processes. Here, we report δ
13
C
carb
and δ
13
C
org
from Late Triassic and Early Jurassic strata near Levanto, Peru, where
intercalated dated ash beds permit temporal calibration of the carbon isotope record. Both
δ
13
C
carb
and δ
13
C
org
exhibit a broad positive excursion through the latest Triassic into the
earliest Jurassic. The first order positive excursion in δ
13
C
org
is interrupted by a negative
shift noted in many sections around the world coincident with the extinction horizon. Our
data indicate that the negative excursion lasts 85 ± 25 kyrs, longer than inferred by
previous studies based on cyclostratigraphy. A 260 ± 80 kyr positive δ
13
C
org
shift
follows, during which the first Jurassic ammonites appear. The overall excursion
culminates in a return to pre-perturbation carbon isotopic values over the next 1090 ± 70
kyrs. Via chronologic, isotopic, and biostratigraphic correlation to other successions, we
find that δ
13
C
carb
and δ
13
C
org
return to pre-perturbation values as CAMP volcanism ceases
and in association with the recovery of pelagic and benthic biota. However, the initiation
of the carbon isotope excursion at Levanto predates the well-dated CAMP sills from
North America, indicating that CAMP may have started earlier than thought based on
35
these exposures, or that the onset of carbon cycle perturbations was not related to CAMP.

2.1. INTRODUCTION
The present-day rate of anthropogenic CO
2
emissions and the contemporaneous
sixth mass extinction in Earth’s history (e.g., Ceballos et al., 2015) motivate studies of
similar past global change and associated loss of biodiversity. The end-Triassic mass
extinction is one such analogue, when the breakup of Pangea was associated with the
rapid emplacement of the Central Atlantic Magmatic Province (CAMP). CAMP
emissions of CO
2
and other volatiles are implicated in putative changes including ocean
acidification (see Greene et al., 2012 for a review) and climate change, which together
are hypothesized to have resulted in the mass extinction (e.g., Guex et al., 2004, 2016;
Palfy and Kocsis, 2014) during the Triassic–Jurassic transition.
Changes in the isotopic composition of sedimentary organic carbon during the
extinction interval suggest major perturbation to the global carbon cycle. However, the
timing and duration of C isotope excursions and their potential relationship to CAMP
remain unclear. An initial negative δ
13
C
org
excursion (ICIE, Hesselbo et al., 2002) is
coincident with the onset of extinction and is followed by a positive excursion observed
in many stratigraphic sections (e.g., Bachan et al., 2012; Guex et al., 2004; Hesselbo et
al., 2002; Williford et al., 2007). Interpretations of the mechanism(s) responsible for the
carbon isotope shifts vary and include input of mantle or sedimentary-rock derived CO
2
(e.g., Bachan and Payne, 2016; Beerling and Berner, 2002; Paris et al., 2016), release of
methane from gas hydrates destabilized by climate warming (Bachan and Payne, 2016;
36
Beerling and Berner, 2002; Palfy et al., 2001), and changes in marine ecosystems
responsible for organic matter cycling and export (e.g., van de Schootbrugge et al., 2013).
Carbon cycle models exploring the causes of excursions during this interval have
remained inconclusive (e.g., Bachan and Payne, 2016; Beerling and Berner, 2002; Paris
et al., 2016), in part because model results depend on the poorly known temporal duration
of isotope excursions. Moreover, few studies have reported coupled records of C isotopes
from both organic and carbonate C for the end-Triassic, further limiting the range of
information available for interpreting C cycle changes. Multiple high-resolution records
of both organic and inorganic carbon isotopes (Kump and Arthur, 1999) offer the
potential to greatly improve understanding of carbon cycle changes during this interval.
U–Pb dating of volcanic ashes from the Triassic–Jurassic succession near
Levanto, in northern Peru, provides a framework to assess carbon isotope changes with
temporal resolution not possible from other sections (Guex et al., 2012; Schaltegger et al.,
2008; Schoene et al., 2010; Wotzlaw et al., 2014). In this study, we report organic and
carbonate carbon isotope records through the Triassic–Jurassic interval from the Levanto
section, use the results to offer new insight into the timing of carbon cycle perturbations,
and compare the Levanto record to other datasets to assess the global significance of the
observed signals spanning the Late Triassic and Early Jurassic.

2.2. LEVANTO SECTION
A continuous section of the Aramachay Formation spanning the majority of the
Rhaetian (latest Triassic) and Hettangian (earliest Jurassic) was sampled at a half-meter
37
scale over 105 meters at a road-cut site near the town of Levanto (locality 6
◦
18
′
29.13
′′
S,
77
◦
53
′
17.55
′′
W). The Aramachay Formation, present throughout much of Peru, was
deposited in extensional basins during the Triassic–Jurassic transition (Rosas et al.,
2007). The strata at Levanto consist of thinly to thickly bedded organic and carbonate-
rich mudstones devoid of traction and current-related sedimentary structures, suggesting
deposition well below storm wave base. Surficial weathering enhances lamination and
bedding differentially across the outcrop, but in polished slabs and thin sections the
lithology is relatively uniform.
Strata are typically thickly bedded in the lower part of the section (0–60 m) where
ash beds are less abundant, but appear thinly bedded where strata are punctuated by
greater ash bed frequency (Fig. 1A, ashes denoted by white stars). In the Supplement
(Fig. S1), marker beds (e.g., Fig. 1B) are reported next to a stratigraphic column
reflecting bedding. Ashes can reach up to 4 cm (Fig. 1C). From 60 to 65 m, meter-scale
packages of thin (∼1 cm) beds alternate with meter-scale individual thick beds, followed
by 30 cm scale packages of thin beds alternating with 30 cm thick beds between 65 and
75 m. The remaining section includes similar alternations in thin and thick beds, which
transition into laterally discontinuous concretionary beds, with some ovate concretions
measuring over 1 m in diameter within the typical mudstone host rock (e.g., Fig. 1D).
Evidence of bioturbation is absent throughout the section, suggesting bottom water
oxygenation remains low through the entire measured interval. Laminae are typically
visible in polished hand samples (Fig. 1E), and examination of 217 thin sections
representing the entire outcrop revealed consistent laminated mudstone lithology,
indicating no major change in depositional environment throughout the section. The
38
consistent lithology through the Levanto section and absence of major environmental or
depositional changes seen in outcrop, hand sample, or thin section (see Fig. 2) leads us to
conclude that the geochemical data presented here are not predominantly controlled by
changes in depositional environment.

20 cm
A C
D
B
5 cm
E
1 m 1 m
30 cm
Fig. 1. Photos of the outcrop from the Levanto section, Aramachay formation,
Peru. (A) Outcrop photo of meters 1–5; small stars indicate orange beds, inter-
preted as ash beds; (B) black marker bed (star) at meter 59; (C) ash bed at meter
30.5; (D) meter-scale concretions from near meter 90; (E) vertically-cut slab
from 13.2 meters.
39

2.3. METHODS
Samples for geochemical and petrographic analyses were collected every half-
meter (225 total samples); surficial weathering was avoided. As noted in section 2, 217 of
225 samples were thin sectioned and evaluated for lithology and degree of alteration. We
40
measured organic and inorganic carbon isotopes (δ
13
C
org
, δ
13
C
carb
), weight percent
carbonate (%CARB), and weight percent organic carbon (%TOC) using an Elemental
Analyzer (Costech) and Automate auto-sampler coupled to a Picarro Cavity Ring Down
spectrometer (e.g., Subhas et al., 2015). Complete carbonate removal is critical for
yielding accurate δ
13
C
org
measurements, given the risk for recalcitrant carbonate phases to
remain after decarbonation in marine sedimentary rocks; thus, we utilized heated (70
◦
C)
1M HCl during decarbonation (e.g., the ‘rinse method’ from Brodie et al., 2011). Isotope
data are reported with stratigraphy in Fig. 3.
Using ash bed dates and ammonite occurrences from Guex et al. (2012) and
Wotzlaw et al. (2014), we assigned ages to samples by interpolating constant
sedimentation rate between ash beds (age model in Fig. 3). To estimate the duration of
isotope excursions, we related ash bed ages to the stratigraphic height encompassed by
each excursion, using a Monte Carlo approach to estimate uncertainties. Specifically, we
randomly sampled 100,000 sets of ages from the normal distribution characterized by the
mean ±1σ age range defined by the U–Pb date of each ash bed. For each set of randomly
sampled ages, we calculated an age model (as in Fig. 3). For each age model, we
determined the duration of each isotope excursion based on the ages inferred for the
stratigraphic height of the excursion start and end points. The resulting distributions of
100,000 determinations of excursion duration were found to be approximately normal;
we report the median and 68% range (effectively equivalent to the propagated 1σ
uncertainty) of each distribution.
Isotopic data and isotope excursion durations with 1σ ranges are shown in Fig. 4,
using the last occurrence of Choristoceras crickmayi to denote the onset of the end-
41
Triassic extinction (ETE; just before 201.51 ± 0.15 Ma; Wotzlaw et al., 2014) and the
first occurrence of Psiloceras spelae to denote the Triassic–Jurassic boundary (TJB;
201.36 ± 0.17 Ma; Wotzlaw et al., 2014). The complete dataset is reported in Appendix
G. More detail, including a discussion of the relationship between our measured section
and the ash beds reported in Guex et al. (2012) and Wotzlaw et al. (2014), detailed
geochemical methods, and error estimation is provided in the Supplement.

2.4. RESULTS
2.4.1. δ
13
C
org
: isotope excursions and their durations
Rhaetian δ
13
C
org
of a positive excursion. These oscillations are approximately
0.5‰ and occur with ∼400 kyr duration during the Rhaetian, suggesting possible
Milankovitch cyclicity. Three points deviate to more positive values ∼202.15 Ma,
followed by an increase at 201.85 Ma that marks the start of a sustained positive
excursion. The broad positive excursion (black bar in Figs. 3 and 4) lasts 1720±90 kyrs,
ending ∼200.1 Ma, approximately 700 kyrs prior to the Hettangian- Sinemurian
boundary. The duration would be longer by ∼300 kyrs if the start of the excursion was at
202.15 Ma (dashed black bar in Fig. 4), but these differences do not affect our
interpretations. Several notable second-order features punctuate the broad positive
excursion, denoted by colored bars on Figs. 3 and 4, including:
1. A positive shift of ∼2‰ begins ∼201.85 Ma, persists for 285 ± 90 kyrs, and reaches a
maximum at the extinction horizon (light green bar, Figs. 3 and 4).
42
20
0
40
60
80
100
30
10
50
70
90
201.0
201.5
202.5
203.5
200.0
202.0
203.0
204.0
200.5
Time (Ma)
Hettangian Stage
System
Ammonite Zone
Meters
Graphic log
(reflects bedding)
Aramachay Formation
ETE
Rhaetian
P. planorbis A. liasicus C. marshi
-4 -2 0 2 4
δ
13
C
carb
‰
0 1 2 3 4
δ
13
C
org
‰
%TOC
0 20 40 60 80
%CARB
U-Pb ages with uncertainty
CAMP U-Pb ages
1090 ± 70 kyrs
1720 ± 90 kyrs
285 ± 90 kyrs
85 ± 25 kyrs
260 ± 80 kyrs
TRIASSIC JURASSIC
5 -30 -29 -28
Fig. 3. δ
13
C
org
, δ
13
C
carb
, %TOC and %CARB records from Levanto, Peru plotted against stratigraphy. Stratigraphic column
reflects bedding. For an expanded bedding column including marker beds, see chapter 2S. In the right panel, ash bed dates from
Guex et al. (2012) and Wotzlaw et al. (2014) are placed with respect to our measured stratigraphic height, and plotted against
time including error. δ
13
C
org
isotope excursions are denoted by colored bars, and their durations are reported in the legend with 1
σ uncertainty. CAMP duration (purple bar) is from Blackburn et al. (2013).
43
2. A negative shift of ∼1.5‰ begins at the extinction horizon, as noted in many other
sections around the world (the aforementioned ICIE of Hesselbo et al., 2002), and
persists for 85 ± 25 kyrs (red bar, Figs. 3 and 4).

-4 -2 0 2 4
201
202
203
204
200
Rhaetian
TRIASSIC
Hettangian
JURASSIC
CAMP U-Pb ages
CAMP
40
Ar/
39
Ar ages
ETE
U-Pb ages
~2700 kyrs
-30 -29 -28
1090 ± 70 kyrs
1720 ± 90 kyrs
285 ± 90 kyrs
85 ± 25 kyrs
260 ± 80 kyrs
δ
13
C
org
‰ δ
13
C
carb
‰
Fig. 4. δ
13
C
org
and δ
13
C
carb
records from Levanto plotted against time. The
end-Triassic Extinction (ETE) is marked by the last occurrence of the ammo-
nite C. crickmayi; the Triassic–Jurassic boundary is the first occurrence of the
ammonite P . spelae (Wotzlaw et al., 2014). Durations of δ
13
C
org
isotope
excursions are denoted by colored bars and are reported in the legend with 1σ
uncertainty. Ash bed dates (orange points with bars) are reported with uncer-
tainties and are from Guex et al. (2012) and Wotzlaw et al. (2014). CAMP
U–Pb duration is from Blackburn et al. (2013) and CAMP
40
Ar/
39
Ar duration
is from Marzoli et al. (2011).
44
3. A renewed positive shift persists for another 260±80 kyrs (orange bar, Figs. 3 and 4)
in association with the Triassic–Jurassic boundary and early Jurassic recovery.

4. For the remainder of the measured section, δ
13
C
org
values gradually return to pre-
perturbation levels over 1090±70 kyrs (blue bar, Figs. 3 and 4).
2.4.2. δ
13
C
carb

δ
13
C
carb
results reveal a prolonged (∼2700 kyrs duration; dark green bar, Fig. 4)
positive excursion of ∼3.5‰, returning to back- ground values near the top of the section
(blue bar, Fig. 4). The falling limb of the positive excursion in δ
13
C
carb
is coincident with
the return to pre-perturbation values in δ
13
C
org
. We do not observe second-order
excursions in δ
13
C
carb
that are found in the δ
13
C
org
record, and we regard single-point
excursions as outliers (discussed in section 5.1).
2.4.3. %TOC and %CARB
%TOC and %CARB are variable through the section (Fig. 3), ranging from 0.1 to
4.5% (TOC) and 1–89% (CARB). %TOC is high during the Rhaetian (mean 1.94%),
declines after the extinction interval through the Triassic–Jurassic boundary, and remains
low in the Hettangian (mean 0.67%). %CARB varies substantially through the section,
with little systematic change from the Rhaetian (mean 55%) to the Hettangian (mean
48%), except for an increase in the range of values towards the top of the section.
2.4.4. Comparison of δ
13
C
org
, δ
13
C
carb
, %TOC, and %CARB records from Levanto

δ
13
C
org
and δ
13
C
carb
both exhibit positive excursions through the latest Triassic and
45
earliest Jurassic. Though the timing of the onset of these excursions differs, both records
shift in tandem from ∼201.2 Ma, as they return to pre-perturbation values. While δ
13
C
carb
values begin to increase in the mid-Rhaetian, δ
13
C
org
is stable for most of the Rhaetian,
before a pronounced positive excursion preceding the ETE and TJB, and then records a
series of second order shifts that are not seen in δ
13
C
carb
. %TOC is high during the
Rhaetian and reaches a local maximum during the first positive excursion in δ
13
C
org
;
%TOC then decreases through the extinction and TJB intervals and remains low during
the Hettangian. %CARB oscillates around an average value of 60%, reaching a local
maximum prior to the positive excursion in δ
13
C
org
. The high %CARB is sustained
through the first positive and negative shifts in δ
13
C
org
.
2.5. DISCUSSION
2.5.1. Assessing effects of diagenesis on the Levanto C isotope records
Records of δ
13
C in the marine environment are always subject to diagenetic
processes, and careful consideration of associated effects is important for robust
interpretation. Overall, smooth isotopic profiles from closely spaced samples that match
similarly- aged profiles from other sections (see section 5.2) generally indicate that local
diagenesis is not the primary control on the isotopic record (Kaufman and Knoll, 1995),
suggesting instead that the records may reflect a global scale process.
More detailed petrographic analyses of our samples, including
cathodoluminescence analyses, support this interpretation. Most samples are
characterized by recrystallized radiolarians in a matrix of micritic calcite, with <10%
detrital component (Fig. 2). Dolomite and siderite were not observed in any samples.
46
Since opal is highly reactive in sediments (e.g., Hesse and Schacht, 2011 and references
therein), we interpret the replacement of radiolarians by carbonate as very early
diagenesis. %CARB varies with some regularity during the Rhaetian (meters 5–45),
perhaps resulting from early cementation in some layers and dissolution and mobilization
in others (e.g., Westphal, 2006). Comparison of δ
13
C
carb
from low %CARB and high
%CARB beds reveals no systematic difference, suggesting very early replacement did not
alter isotopic values. Furthermore, there is no systematic offset in δ
13
C
carb
between thin
and massive beds or between concretionary and thin beds. Consequently, we interpret the
concretions to be very early diagenetic, preserving a meaningful signal of seawater at the
time of deposition. Although concretions often do exhibit an offset in δ
13
C
carb
relative to
adjacent beds in other settings (e.g., Mozley and Burns, 1993), diagenetic concretions
from the early Jurassic are also known from New York Canyon, Nevada (K. Ritterbush
and S. Loyd, unpublished data) and similarly display no offset in δ
13
C
carb
. That both early
Jurassic localities contain concretions without offset in δ
13
C
carb
suggests seawater and
pore water chemistry following the TJB may have been pre-disposed for very early
diagenetic carbonate formation.
Outliers from the generally smooth δ
13
C
carb
curve offer additional insight into
diagenetic processes in this section. Three samples from near the Triassic–Jurassic
boundary have anomalously positive values (Fig. 4, unfilled circles). Of the dominant
pore water reactions and metabolisms, methanogenesis is most likely to generate positive
δ
13
C
carb
values (e.g., Loyd et al., 2012) and also leads to Mn
2+
and Fe
2+
incorporation,
imparting luminescence. The greater cathodoluminescence in samples with elevated
δ
13
C
carb
(see supplemental Fig. S2) is thus consistent with diagenetic alteration of these
47
samples in the methanogenesis zone via carbonate reduction (e.g., Whitcar, 1999). Given
that other samples in our section exhibit much lower luminescence, we conclude that the
overall record likely reflects changes in seawater composition even though all samples
have undergone some level of alteration and recrystallization.

2.5.2. Inorganic carbon isotopes: correlation and comparison with other sites
Fig. 5 shows Triassic–Jurassic paleogeography and marks the sites for δ
13
C
records in Figs. 6 and 7. δ
13
C
carb
of bulk carbonate data from Levanto, Val Adrara
(Bachan et al., 2012), and Lyme Regis (Korte et al., 2009) are compared in Fig. 6. These
records corroborate a broad positive excursion in δ
13
C
carb
extending from the late Triassic
into the early Jurassic. A ∼3.5‰ positive shift in δ
13
C
carb
from the Rhaetian to
Hettangian, with a maximum near the TJB, is followed by a return to pre-excursion
values during the Hettangian. Like our data from the Levanto section discussed in section
5.1, the Val Adrara section has some outlier points attributed by Bachan et al. (2012) to
diagenetic alteration, but we note that the vast majority of the data follow similar trends
between sections. The similarity in high-resolution datasets from stratigraphic sections
deposited in different ocean basins suggests the first order positive excursion in δ
13
C
carb
Levanto
VA
CAMP CAMP
Tethys Panthalassa
UK
KP
Ti
Fig. 5. Late Triassic paleogeographic
map with locations of St. Audrie’s Bay
and Lyme Regis (‘UK’), Val Adrara
(‘V A’), Kennecott Point (‘KP’), Tiourj-
dal (Ti), Levanto, and the Central
Atlantic Magmatic Proince (CAMP)
after Kuroda et al. (2010).
48
likely represents a global signal (e.g., Kaufman and Knoll, 1995). Bertinelli et al. (2016)
report δ
13
C
carb
from the Pignola-Abriola section (Southern Apennines, Italy) spanning the
Norian–Rhaetian boundary (‘NRB’), in which a minimum occurs at the NRB and a slow
positive shift follows, suggesting a global positive excursion in δ
13
C
carb
may begin at the
NRB.
Other Triassic–Jurassic datasets available from the southwest UK include
molluscan data from Lyme Regis (Korte et al., 2009) and a correlative section in
Doniford Bay (Clémence et al., 2010). The section from Doniford Bay was considered
influenced by meteoric diagenesis by Clémence et al. (2010) and is thus not considered
here. Although molluscan data is preferred by Korte et al. (2009) to their bulk data (Fig.
6), the spread of data in mollusk shells within a single horizon is often >1‰, and offset
between DIC and δ
13
C
carb
in molluscs is common (e.g., McConnaughey and Gillikin,
2008). Our focus is on understanding how C isotopes reflect changes in the global C
cycle through time, and we emphasize the similarities in a broad positive excursion in
bulk carbonate δ
13
C
carb
surrounding the TJB in sections where diagenesis is not the
dominant factor.
Interestingly, the peak in the positive δ
13
C
carb
excursion at Levanto occurs at the
transition from high %TOC during the Rhaetian to low %TOC during the Hettangian
(Fig. 3). The opposite trend has been observed in Tethyan sections (Hesselbo et al., 2004)
and attributed to increased anoxia and preservation of organic matter during the
Hettangian (van de Schootbrugge et al., 2013). The consistent lack of bioturbation at
Levanto suggests little change from the Rhaetian to the Hettangian in bottom water
oxygenation, so the changes in %TOC could reflect productivity. Although this could be
49
merely a local effect, increased %TOC would also be consistent with organic matter
burial driving the positive excursion in δ
13
C
carb
(see section 2.5.5).

2.5.3. Organic carbon isotopes: correlation and comparison with other sites
Bulk δ
13
C
org
in sediments can reflect the input of organic matter from different
sources, including marine and lacustrine algae as well as land plants (e.g., Meyers, 1994).
Characterizing the organic matter in detail (e.g., at the biomarker level) is beyond the
scope of this study, but similarities in the depositional environment throughout the
Levanto section, with no clear change in detrital or continental derived input, lead us to
conclude that source changes are not the primary cause of the δ
13
C
org
shifts we observe.
Moreover, even if parts of the Levanto δ
13
C
org
record are influenced by changing sources,
we observe similar patterns in other records from the same time interval, suggesting
underlying global- scale processes are responsible.
Tethys Panthalassa
This study
Korte et al., 2009
Bachan et al., 2012
δ
13
C
carb
‰
VPDB
0
20
40
60
80
100
-4 -2 0 2 4
0
100
200
400
-2 0 2 4 6
-2 0 2 4 6
P. planorbis C. marshi
P. pl.
A. liasicus
16
12
8
4
0
TRIASSIC
Hettangian Rhaetian
JURASSIC
J T
J T
Levanto
Peru
Val Adrara
Italy
Lyme Regis
United Kingdom
300
A. liasicus
Fig. 6. δ
13
C
carb

records from
Levanto (this
study), Val
Adrara (Bachan
et al., 2012), and
Lyme Regis, UK
(Korte et al.,
2009) plotted
against stratigra-
phy and reported
ammonite
biozones. Isoto-
pic shifts are
correlated with
gray lines.
50
-32 -30 -28 -26
10
30
50
70
90
-31 -29 -27 -25
0
100
200
300
400
-30 -28 -26
4
8
-26 -24 -22 -20
Tiourjdal Section
Morocco
Dal Corso et al., 2014
Levanto
Peru
This study
St. Audrie’s Bay
United Kingdom
Hesselbo et al., 2002
Ruhl et al., 2010
Val Adrara
Italy
Bachan et al., 2012
Kennecott Point
Haida Gwaii, Canada
Ward et al., 2001
Williford et al., 2004
TRIASSIC
Hettangian
P. planorbis A. liasicus
P. planorbis
10
20
30
0
CAMP
-28
Rhaetian
JURASSIC
J T
Tethys Panthalassa Terrestrial
ICIE
10
30
50
70
90
130
150
170
190
J T
J T
-30 -29 -28
A. liasicus
P. planorbis
0
2
6
110
C. marshi
C. marshi
A. liasicus
1090 ± 70 kyrs
285 ± 90 kyrs
85 ± 25 kyrs
260 ± 80 kyrs
Fig. 7. δ
13
C
org
records from Levanto (this study), St. Audrie’s Bay (Hesselbo et al., 2002, 2004; Ruhl et al., 2010), Val
Adrara (Bachan et al., 2012), Morocco (Dal Corso et al., 2014) and Kennecott Point (Ward et al., 2001; Williford et al.,
2007). Isotopes are reported against meters of stratigraphy with ammonite biozones. Isotopic shifts in records are correlated
with gray lines. Colored bars indicate isotope shifts and their durations for the Levanto section, which we correlate to other
sections, thus denoting timing for shifts in other stratigraphic sections. Note that in the St. Audrie’s Bay record, the last
positive excursion ends earlier than in other sections (using ammonite biozones to deduce time); we interpret this as a local
effect in this section, since all other sections take longer to ameliorate δ
13
C
org
excursions.
51
In Fig. 7, δ
13
C
org
data from Levanto are compared to published records with an
emphasis on high resolution and long temporal records where δ
13
C
carb
has also been
measured. These include records from Val Adrara (Bachan et al., 2012), St. Audrie’s Bay
(Hesselbo et al., 2002, 2004; Ruhl et al., 2010), Kennecott Point (Ward et al., 2001;
Williford et al., 2007) and Tiourjdal, Morocco (Dal Corso et al., 2014). We correlated
records using ammonoid biostratigraphy where available and C isotope
chemostratigraphy. Most of the second-order features in the Levanto δ
13
C
org
record are
present in the Val Adrara, St. Audrie’s Bay, and Kennecott Point sections, with ammonite
biostratigraphy corroborating the coincidence of the C isotope excursions. The terrestrial
Tiourjdal section shows a positive isotope excursion aligned with the first positive shift at
Levanto (Fig. 7, light green bar), pointing to a C cycle perturbation in both marine and
terrestrial environments prior to the ETE and TJB.
While the thickness of relative stratigraphy and magnitude of the C isotope
excursion varies from place to place as a function of local effects (e.g., sediment
accumulation rate, water depth, nutrient input, organic matter type), the similarity across
records from multiple ocean basins indicates that the isotopic features at Levanto can be
considered global in nature and most importantly their durations now known, for the first
time, within error of the radioisotopic dating and sedimentation rate interpolation from
Levanto. For example, the negative shift in δ
13
C
org
coincident with the extinction horizon
(the widely-discussed ICIE) is now calibrated to have lasted approximately 85 (±25)
kyrs. The duration of this excursion has previously been estimated as 20–40 kyrs based
on cyclostratigraphy (Ruhl et al., 2010), <10–20 kyrs based on carbon cycle model results
(Bachan and Payne, 2016; Paris et al., 2016), and ∼70 kyrs (Beerling and Berner, 2002).
52
Our results suggest a more protracted negative shift in agreement with Beerling and
Berner (2002). One explanation for the shorter durations inferred from cyclostratigraphic
studies in Tethys is that the excursion often occurs in the shallowest portion of Tethyan
sections (discussed in Lindstrom et al., 2017). The deeper section at Levanto is both
expanded stratigraphically with respect to other sections and is deep enough to
continuously record deposition during sea level fall. Although the errors on our estimates
of excursion duration are significant, they suggest a broad range of possible lengths of
time, including longer durations than have been previously considered, may be
reasonable for the ICIE and need consideration in future modeling.
Constraining the duration of the ICIE for the first time with radioisotopic ages
sets the groundwork for untangling its causes and its ties to the ETE. Though
interpretations have varied, large-scale methane release has been frequently invoked as a
necessary mechanism, partly because of the large magnitude and short duration of the
excursion inferred in previous studies (Beerling and Berner, 2002). The prolonged
duration and smaller isotopic shift we have measured at the Levanto section suggest that
the methane addition hypothesis should be revisited in future modeling studies.
2.5.4. Offset in δ
13
C values between Tethys and Panthalassa
In Fig. 8, the comparison of the two high-resolution paired (δ
13
C
carb
and δ
13
C
org
)
records from Val Adrara and Levanto reveals an apparent offset in absolute magnitude,
even as the broad trends with time are similar. Interestingly, these two sections were
deposited in different ocean basins (Val Adrara in Tethys, versus Levanto in
Panthalassa), hinting at a potential difference in isotopic composition of DIC between the
53
two ocean basins. The offset between the two records is ∼2‰ in the Rhaetian and
expands to ∼4‰ at the maxima in δ
13
C
carb
and δ
13
C
org
at both sites, before returning to a
∼2‰ offset in the late Hettangian. A 1–2‰ offset is observed today between the Atlantic
to Pacific oceans and is a product of organic carbon remineralization during transport of
waters along the global ocean conveyer belt (Kroopnick, 1985). If the Val Adrara and
Levanto records are representative of their respective ocean basins, the difference may
suggest similar conveyer belt ocean circulation processes were active during the Triassic–
Jurassic transition. Although alternative explanations, such as depositional depth,
diagenesis, and changes in local water masses, could also explain the offset between the
two records, other records also point to a systematic, ocean basin-associated difference
(Figs. 6 and 7). Further confirmation will rely on generating more long- duration, high-
resolution records of paired δ
13
C
carb
and δ
13
C
org
that capture a wide snapshot of time at
multiple locations globally.
2.5.5. Decoupled carbonate and organic carbon isotope records during the Late
Triassic and Early Jurassic
Carbon isotope records and modeling studies from the Triassic– Jurassic interval
have classically focused on the boundary and emphasized the negative shift in δ
13
C
org
across the extinction horizon (the ICIE mentioned in sections 1 and 2). In the Levanto
record, we observe a positive excursion in both δ
13
C
carb
and δ
13
C
org
spanning the Late
Triassic and Early Jurassic. Immediately above and below the boundary, the δ
13
C
org
record is interrupted by second- order excursions, including the widely discussed
negative ICIE, but these features are not seen in δ
13
C
carb
. We conclude from our
comparisons to other studied sections that decoupling between δ
13
C
carb
and δ
13
C
org
is not
54
exclusive to Levanto (e.g., Bertinelli et al., 2016; Williford et al., 2007), but may have
been a feature of the global ocean and/or ocean ecosystem (see also Bachan et al., 2012).
Such decoupling is likely to have important implications for understanding the behavior
of the carbon cycle during the mass extinction and emplacement of CAMP. We suggest
that C cycle models applied to the TJB should consider this decoupling and include
consideration of observed changes in δ
13
C
carb
records through the Rhaetian,
complementing previous modeling efforts that have largely focused on δ
13
C
org
records.
Reconciling the Rhaetian shift in δ
13
C
carb
and stasis in δ
13
C
org
is not
straightforward. While the positive excursion in δ
13
C
carb
might be explained by an organic
matter burial event, it is puzzling that δ
13
C
org
does not also respond to this forcing for two
million years (e.g., see Kump and Arthur, 1999). One possibility might be that
atmospheric pCO
2
rose during the Rhaetian, providing the necessary weathering and
nutrient supply to continue burying organic matter, while also increasing the fractionation
factor between DIC and marine biomass, as expected at high pCO
2
(Kump and Arthur,
1999). CAMP could provide a plausible source of this CO
2
through the Rhaetian (Kuroda
et al., 2010). The result would be increasing δ
13
C
carb
(as more organic matter is buried)
and increasing %TOC, but relatively muted effects on δ
13
C
org
. %TOC does increase
during the Rhaetian at Levanto, although the preservation of organic matter is strongly
controlled by local effects such as oxygen exposure time (e.g., Hedges et al., 1999) and
few if any other records of %TOC exist through the Rhaetian for comparison. However,
the balance between organic carbon burial and changing fractionation factor required to
maintain constant δ
13
C
org
seems fortuitous. Also, the enhanced burial of organic matter
would be expected to draw down CO
2
, and indeed pedogenic carbonates record
55
decreasing not increasing pCO
2
during the Rhaetian (Schaller et al., 2014). The large-
scale, long-term decoupling that we observe in the Rhaetian thus remains enigmatic.
However, the magnitude and timing of changes in δ
13
C
org
and δ
13
C
carb
may differ even
when subject to the same forcing (Kump and Arthur, 1999), so while decoupled, the
δ
13
C
org
and δ
13
C
carb
records across the end-Triassic may still be attributed to the same
fundamental perturbation to the C cycle.

Later in the Levanto section, we also find decoupling when the positive excursion
in δ
13
C
org
begins at ∼201.8 Ma, immediately prior to the ICIE and the extinction interval.
This positive excursion in δ
13
C
org
is geographically widespread and may hold important
clues about global biogeochemical change immediately prior to extinction. The positive
-31 -30 -29 -28 -27 -26 -4 -2 0 2 4 6
Triassic Jurassic
δ
13
C
org
‰ δ
13
C
carb
‰
δ
13
C
org
‰ δ
13
C
carb
‰
ICIE
Val Adrara
(Bachan et
al. 2012)
Levanto
(this study)
Fig. 8. δ
13
C
org
and
δ
13
C
carb
records
from Levanto
(green points)
and Val Adrara
(orange points)
plotted on the
same δ
13
C axes,
and with relative
time on the
y-axes. Note
offset between
green and orange
points in both δ
13
C
org
and δ
13
C
carb

records.
56
isotope excursion has been attributed to early extinctions in algae (van de Schootbrugge
et al., 2008) and pollen (Lindstrom et al., 2012), changing the makeup of organic matter
and thus its isotopic composition. Some authors have additionally invoked carbonate
productivity collapse during this interval (Greene et al., 2012), but this is not observed in
our %CARB record from Levanto. Although a biotic crisis in calcifiers took place
globally at the time, carbonate production may have shifted towards an
abiogenic/nonskeletal mode (van de Schootbrugge et al., 2007). Shifting fractionation
associated with biological community change but relatively consistent carbonate
production could explain the observed decoupling of isotope records during this interval.
Additional paired records of carbonate and organic carbon isotopes, extending from the
early Rhaetian through the Hettangian, will be needed to corroborate the decoupling
observed in Levanto and to better understand its implications for the carbon cycle. Such
records have thus far been lacking, but our results suggest that they will be vital to
unraveling the history of environmental change at this time.
2.5.6. Implications for timing of C cycle perturbation with respect to CAMP
magmatism
U–Pb zircon dating of CAMP in North America and Morocco indicates that
volcanism initiated ∼201.56 Ma and ceased ∼200.9 Ma (Blackburn et al., 2013). Our new
chronologically defined δ
13
C
org
record from Levanto shows that the negative carbon
isotope shift at the extinction horizon is coincident with the initiation of CAMP
volcanism in North America (Figs. 2 and 3). Furthermore, both δ
13
C
org
and δ
13
C
carb
return
towards background values after North American eruptions apparently ceased. The return
to background occurs within the A. liasicus ammonite biozone (Fig. 3), coincident with
57
major ammonite diversification (e.g., Guex et al., 2004, 2012), robust siliceous sponge
ecosystem development (Ritterbush et al., 2014, 2015), and the cessation of Hg
anomalies related to CAMP volcanism (Thibodeau et al., 2016). Taken together, we
suggest that the amelioration of the isotopic perturbation may have occurred with CAMP
cessation and the initiation of the recovery of the biosphere.
In contrast, the δ
13
C
carb
positive shift during the Rhaetian and the first δ
13
C
org
positive shift began before the earliest CAMP dates from North America.
40
Ar/
39
Ar dates
suggest an earlier initiation of CAMP (Dal Corso et al., 2014; Marzoli et al., 2004, 2011),
and osmium and strontium isotopes suggest significant mantle input during much of the
Rhaetian, which could possibly be a sign of very early CAMP volcanism (Callegaro et
al., 2012; Kuroda et al., 2010). Such early volcanism could explain the origin of the long
Rhaetian δ
13
C

organic carbon burial as suggested in section 2.5.5. Alternatively, other
processes not linked to CAMP may have initiated the C-isotope excursions we observe.
For example, the Triassic–Jurassic boundary coincides with the transition from carbonate
deposition on shelves to the deep sea, which could affect global signals in C isotopes. Or,
if redox conditions changed globally (e.g., van de Schootbrugge et al., 2013), enhanced
preservation of organic matter might have influenced C isotopes. In summary, we find
clear synchroneity between the end of carbon isotopic anomalies, biotic recovery, and the
cessation of CAMP, but the coincidence during initiation is less clear. The temporally-
calibrated δ
13
C record from Levanto demonstrates that the oft-cited connection between
the onset of CAMP and the carbon cycle perturbation associated with the ETE is not as
clear as implied by the current literature.

58
2.6. CONCLUSIONS
Carbon isotope records from Levanto, Peru, reveal distinct excursions that can be
linked to those in other sections from across the global oceans at the time, and that are
now defined in duration using ash beds dated from the Levanto section. The termination
of the excursions is coincident with ammonite diversification, robust metazoan silica
development, and possible cessation of CAMP volcanism. The δ
13
C
org
and δ
13
C
carb

records are decoupled, suggesting different mechanisms may have influenced the organic
and inorganic carbon sub-cycles, though both could have ultimately been related to the
same forcing associated with volcanism. If the positive shifts in δ
13
C are related to the
onset of CAMP, we hypothesize an earlier onset of CAMP volcanism than U–Pb North
American and Moroccan basalts suggest, leaving open the question of whether CAMP
volcanism initiated in the late Rhaetian (∼201.8 Ma) or millions of years earlier.
Alternatively, carbon cycle perturbations may have begun prior to CAMP volcanism, and
other processes not currently appreciated may have operated before the end Triassic
extinction and the onset of CAMP volcanism.

59
REFERENCES
Bachan, A., Payne, J.L., 2016. Modeling the impact of pulsed CAMP volcanism on
pCO2 and δ
13
C across the Triassic–Jurassic transition. Geol. Mag. 153 (2), 252–270.
http://dx.doi.org/10.1017/S0016756815000126.
Bachan, A., van de Schootbrugge, B., Fiebig, J., McRoberts, C.A., Ciarapica, G., Payne,
J.L., 2012. Carbon cycle dynamics following the end-Triassic mass extinc- tion:
constraints from paired δ
13
C
carb
and δ
13
C
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68
2S. SUPPLEMENTAL INFORMATION FOR CHAPTER 2
2S1. Sample collection and stratigraphic positioning
Samples were collected approximately every half-meter following the stratigraphy
of Schaltegger et al. (2008), Schoene et al. (2010), Guex et al. (2012), and Wotzlaw et al.
(2014). The section spanning 0 to ~110 m in these studies is continuous and includes the
majority of the Rhaetian and Hettangian; above and below this area, rocks are variably
faulted and covered. We only sampled the complete, continuous section and measured
105 meters of stratigraphy, compared to 109 meters reported by Schaltegger et al. (2008).
To relate our stratigraphic meters to theirs and to utilize U-Pb zircon dates and ammonite
occurrences reported by Guex et al. (2012) and Wotzlaw et al. (2014), we assumed our
105 meters was equivalent to their 109 meters, since the section is covered above and
below (providing distinct start and end points). To define the stratigraphic position where
a given ammonite or ash occurs (i.e. first occurrence of Psiloceras spelae, Guex et al.,
2012 Fig. 2, 65.4 meters), we normalized to the reported position, e.g. 105m/111m x 65.4
m = 61.9 meters in our measured section. We were able to tie in three positions on shared
stratigraphic columns with the group who conducted the prior published work (Jean
Guex, pers. comm.). These tie-ins include the black marker beds (“BB”; Figure S1): BB1
which we recorded as 59m and Jean Guex recorded as 60m; and BB2 at 72m in our
column and 75m in Jean Guex’s column (where expected based on our normalized
stratigraphy). We also correlated our collection of P. tilmanni (identified by Jean Guex),
which was found within the expected range. It is unrealistic to report each ash bed from
the Levanto section at the 100 meter scale, since in many cases >5 ashes may be found in
a single meter (e.g., Figure 1A of the main text). Nonetheless, our correlation with
69
marker beds and ammonites lends confidence to the correlation between our isotope
records and the previously defined U-Pb chronology: although slight discrepancies exist,
they are <2m. We do not think such small differences alter our interpretations, since the
calculated time between samples in one meter in the center of the section is
approximately 20 kyrs; the 2s uncertainty on ash beds in this interval is about ± 0.14 Ma,
or ± 140 kyrs, which is far greater than the uncertainty associated with the two meters
(maximum) discrepancy between our sampling.
A close examination of the four previously published papers reveals slight
differences (2-3 meters) in the reported ash bed and ammonite occurrences depending on
publication. We used the ash bed and ammonite stratigraphic heights from Guex et al.
(2012) and the updated ages from Wotzlaw et al. (2014). For the three ash bed ages
reported in Guex et al. (2012) that were not also in Wotzlaw et al. (2014), we used
recalculated ages based on the calibration of the EARTHTIME
202
Pb-
205
Pb-
233
U-
235
U
tracer solution used by Wotzlaw et al. (2014) (Blair Schoene, pers. comm.).

2S1.2 Sample processing and methods
Field samples of approximately 900 cm
3
were returned to USC and cut so that
weathered surfaces and veins were removed. Samples were then crushed in a jaw crusher
and powdered to 95% passing through 200 mesh by Actlabs, which uses mild steel
grinding mills, with cleaning sand used between each sample.
2S2.1 δ
13
C
org
and %TOC analyses
An aliquot of powder (~1 g) was treated in 40 mL of 1M hydrochloric acid and
heated to 70°C for four hours to remove all carbonate mineral phases (after Galy et al.,
70
2007; analogous to the ‘rinse method’ from Brodie et al., 2011 and similar to the methods
used by Ward et al., 2007; Hesselbo et al., 2003). In our comparison with other published
organic carbon isotope records (Fig. 5 of the main text) we have not included additional
Triassic-Jurassic sections where C isotope data were collected using different methods
that may confound comparison (e.g., without heating during carbonate removal, which is
necessary to remove recalcitrant phases; cf. Galy et al., 2007).
Samples were rinsed three times with deionized water and dried at 50°C. Weight
percent organic carbon (%TOC) was determined on the residual decarbonated powder
using a Picarro cavity ring down spectrometer (CRDS) (G2131-i) coupled via a Picarro
Liaison (A0301) to a Costech Elemental Combustion System (EA 4010). Picarro
measurements of CO
2
concentration were calibrated to determine %C in samples using
the USGS-40 standard (L-glutamic acid) weighed at 5 different samples masses and run
at the beginning and end of each set of ~15 samples. Determination of %TOC took into
account the amount of carbonate lost during decarbonation. Errors were calculated by
replicate analysis of samples and standards (typically ~2 replicates per sample; see
Supplementary Table 1). Standard deviation of replicates for measured %TOC was ±0.08
on average, or ~ ±3% of the measured value (1σ, standard deviation). Because of
potential errors introduced by small amounts of sample loss during liquid decarbonation,
including via solubilization of organics (Galy et al., 2007), we take a conservative
estimate of ±10% uncertainty on the measured value for reported %TOC.
The isotopic composition of organic carbon (δ
13
C
org
) was also determined using
the Picarro CRDS (G2131-i) and is reported in delta notation relative to the Vienna Pee
Dee Belemnite (VPDB) standard. The uncertainty on δ
13
C
org
values was assessed from
71
replicate runs of standards (in-house carbonate standards USGS 40 and AR15) and
samples. Replicates agree to better than <0.2‰ (1σ), with average s of 0.06‰.
Uncertainties and blanks associated with this methodology of C isotope analysis are
further discussed in Subhas et al. (2015).

2S2.2. δ
13
C
carb
and %TIC analyses
δ
13
C
carb
and %TIC were measured on aliquots of the same powdered sample used
for organic carbon analysis. Depending on the sample’s %TIC, 3-200 mg of sample was
weighed into 10mL glass Exetainer vials with rubber septa caps. Vials were evacuated
and acidified with 1 mL 30% H
3
PO
4
. Samples and standards were heated for 80 minutes
in a water bath at 70°C to ensure that C associated with all carbonate phases was released
as CO
2
. Samples were then run on a Picarro CRDS coupled to an Automate prep device,
which sparges the solution with N
2
gas to drive CO
2
into the analyzer. In-house carbonate
standards Optical calcite (OPT) and AR15 were run at different masses to calibrate %C
and to check accuracy and precision of isotope values. Errors were calculated by replicate
analyses of samples and standards. Average error (1σ) for %TIC measurements was
±0.04, or <1% of the measured value. Weight percent carbonate (%CARB) was
calculated from measured %TIC, assuming all inorganic carbon is CaCO
3
as opposed to
dolomite, given the absence of dolomite or other carbonate phases observed in thin
sections of these samples. The isotopic composition of inorganic carbon is reported in
delta notation (δ
13
C
carb
) relative to the Vienna Pee Dee Belemnite (VPDB) standard. The
uncertainty of δ
13
C
carb
values was assessed from replicate runs of standards (including
72
OPT calcite and internal carbonate standards) and samples. Standard deviations of sample
replicates were on average ±0.057 ‰ (1σ).

73
20
0
40
60
80
100
30
10
50
70
90
Stage
System
Formation
Meters
Ammonite Biozone
Ammonite Occurences
Hettangian
Aramachay
Rhaetian
JURASSIC
ETE
TRIASSIC
P. planorbis A. liasicus C. marshi
Graphic log (reflects
bedding)
Tie in with previous studies
BB2, see supplement
P. tilmanni
BB1, see supplement
and Fig 1B, main text
(bottom of section)
(top of section)
Alsatites
Kammerkarites
Psiloceras tilmanni
First Occurence
Psiloceras spelae
Last Occurrence
Choristoceras crickmayi
Vandaites saximontanus
Figure S1. Stratigraphic column
reflecting bedding seen in outcrop
with our measured stratigraphic
height. Ammonite occurences are
from Guex et al. (2012) and are
placed on our column according to
the methods section (supplemental
info). Ammonite biozones from
Guex et al. (2012). Stars denote
tie-in points with previous studies.
74
δ
13
C carb = 0.40‰ δ
13
C carb = 4.99‰ δ
13
C carb = 0.93‰
LV123
cathodoluminescence plane light
LV124 LV125
plane light plane light plane light
CL CL CL
500 μm
500 μm 500 μm
500 μm 500 μm
500 μm
Figure S2. Cathodoluminescent (top row) and plane light (bottom row) photomicrographs of Levanto
samples. Sample LV124 is an outlier on the δ
13
C
carb
curve (Figs 2 and 3, main text). The heavy
isotope value and enhanced luminosity with respect to samples sub and super adjacent to it (LV123
and LV125) lead us to conclude an increase in Mn
2+
and Fe
2+
and generation of heavy δ
13
C
carb
from
carbonate reduction during methanogenesis is responsible for this anomalous isotopic value.
75
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Hesselbo, S. P., Robinson, S. A., Surlyk, F., 2004, Sea-level change and facies
development across potential Triassic-Jurassic boundary horizons, SW Britain:
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764903-033.
Ruhl, M., Deenen, M. H. L., Abels, H. A., Bonis, N. R., Krijgsman, W., Kurschner, W.
M., 2010, Astronomical constraints on the duration of the early Jurassic Hettangian
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Bay/East Quantoxhead, UK): Earth and Planetary Science Letters v. 295, p. 262-276,
doi: 10.1016/j.epsl.2010.04.008.
Schaltegger, U., Guex, J., Bartolini, A., Schoene, B., Ovtcharova., M., 2008, Precise U-
Pb age constraints for end-Triassic mass extinction, its correlation to volcanism and
Hettangian post-extinction recovery: Earth and Planetary Science Letters v. 267, p.
266-275, doi:10.1016/j.epsl.2007.11.031.
Schoene, B., Guex, J., Bartolini, A., Schaltegger, U., Blackburn, T.J., 2010, Correlating
the end-Triassic mass extinction and flood basalt volcanism at the 100 ka level:
Geology, v. 38, no. 5, p. 387–390, doi: 10.1130/G30683.1.
Subhas, A. V., Rollins, N. E., Berelson, W. M., Dong, S., Erez, J., Adkins, J. F., 2015, A
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Ward, P. D., Garrison, G. H., Williford, K. H., Kring, D. A., Goodwin, D., Beattie, M. J.,
McRoberts, C. A., 2007, The organic carbon isotopic and paleontological record
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Muller Canyon, Nevada, USA: Palaeogeography, Palaeoclimatology, Palaeoecology,
v. 244, p. 281-289, doi:10.1016/j.palaeo.2006.06.042.
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Ward, P.D., Haggart, J. W., Carter, E. S., Wilbur, D., Tipper, H. W., Evans, T., 2001,
Sudden productivity collapse associated with the Triassic-Jurassic boundary mass
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Williford, K. H., Ward, P. D., Garrison, G. H., Buick, R., 2007, An extended organic
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78
Chapter 3. Rising oxygen in the Late Triassic may have
made the Earth System more susceptible to perturbation
before the end-Triassic extinction

OPENING STATEMENT
In Chapter 2, I reported high resolution organic and inorganic C isotopes from the
Levanto section, constraining duration of changes to the C cycle and raising the question
of why inorganic C isotopes change during most of the Rhaetian at Levanto, and what
this may have had to do with CAMP and the end-Triassic extinction. In Chapter 3, I
report stable nitrogen isotopes and trace metal concentrations from the same samples in
an effort to understand changing redox and related biogeochemistry prior to and during
the ETE.
I weighed out the samples for δ
15
N analysis and we sent them to the UC Davis
Stable Isotope Facility. I plotted and analyzed the nitrogen isotope data and interpreted it
with Will Berelson. I digested and diluted all samples for trace element analyses and ran
them at USC on Sergio Sañudo-Wilhelmy and Jim Moffett’s ICP-MS with Paulina
Pinedo-Gonzalez, who set up the instrument and taught me how to work up the trace
metal data. I worked up the data, plotted, and analyzed the data and made the figures and
interpreted the data and wrote the paper. Josh West helped write the paper with
contributions from all other coauthors. Josh and I decided to use an aqua regia digestion
(vs full Hf digestion because 1) it’s much safer and 2) during the literature review Xu et
79
al. (2012) recommended this approach for paleoredox applications. This paper is in
preparation for submission.

ABSTRACT
The end-Triassic extinction (~201.51 ± 0.15 Ma; ETE) coincided with the
emplacement of the Central Atlantic magmatic province (CAMP), which raised
atmospheric CO
2
and caused major environmental disruption during the ETE and Early
Jurassic. Here, we investigate the biogeochemical changes in the ocean before, during,
and after the ETE using stable nitrogen isotopes (δ
15
N) and trace metal concentrations
from a section spanning the Triassic-Jurassic Boundary near Levanto in Northern Peru.
This well-dated section is comprised of low oxygen, carbonate-rich mudstones exhibiting
little lithologic change during the ~4 million year duration of deposition represented by
this section. Our data suggest a nitrogen cycle similar to today’s leading up to the ETE,
with systematic isotope fluctuations consistent with the expansion and contraction of
oxygen minimum zones on orbitally-forced (~405 kyr) timescales. A 9‰ to 2‰ shift in
δ
15
N during the last 2.5 Ma of the Triassic coincides with an increase in the concentration
of redox-sensitive trace metals (U and V). A shift to lighter δ
15
N values is also seen in
other nitrogen isotope records spanning the Triassic-Jurassic boundary, suggesting
decreasing δ
15
N during the Late Triassic may be a global signal. We interpret this
decrease in δ
15
N and increase in trace metals as indicative of increasing oxygenation prior
to the ETE. Upon initiation of CAMP magmatism, we find evidence for euxinia
(increased Mo concentrations) coincident with negative excursions in δ
13
C
org
. Trace
metals decrease to minima during this δ
13
C
org
shift, suggesting rapid expansion of ocean
80
anoxia, as seen in previous studies. We speculate that increasing oxygenation prior to
CAMP emplacement may have predisposed the oceans to perturbation during the onset of
CAMP magmatism and volatile release, speculating that more aerial extent of oxygenated
waters may have made the Earth System more susceptible to perturbation.

3.1. INTRODUCTION
Mass extinction events represent dramatic upheavals in the history of life on
Earth, and understanding their causes remains one of the compelling questions in the
Earth and life sciences. Some mass extinctions coincided with globally extensive
volcanism and CO
2
release (e.g., end Permian, end-Triassic, end Cretaceous), and mass
extinction events may hold information about the planetary response to CO
2
rise.
Anthropogenic emissions push atmospheric pCO
2
to levels not seen for at least the past 3
Myrs and on track to rise to atmospheric pCO
2
levels not seen in 25 Myrs (Foster et al.,
2017) and warrant study of past C cycle perturbations. Despite the temporal overlap in
CO
2
increase and mass extinction, key questions remain unanswered about the chain of
environmental consequences that follows CO
2
release, and particularly about which of
these consequences can be held accountable for driving biotic crisis.
The so-called “kill mechanism” for the end-Triassic mass extinction (ETE;
~201.51 ± 0.15 Ma; Wotzlaw et al., 2014), which saw the largest decline of “modern
fauna” in the geologic record (Sepoksoki 1981, Alroy 2010), is particularly enigmatic.
The ETE coincided with the emplacement of the Central Atlantic Magmatic Province
(CAMP; Marzoli et al. 1999), associated with the breakup of Pangea. CAMP
emplacement raised atmospheric pCO
2
(Schaller et al., 2012; Schaller et al., 2015;
81
Steinthorsdottir et al., 2011) and likely led to marine anoxia (van de Schootbrugge et al.,
2013; Jost et al., 2017), euxinia (Kasprak et al., 2015; Schoepfer et al., 2016), and ocean
acidification (Greene et al., 2012), which have all been proposed as potential extinction
mechanisms.
The role of shifting marine redox conditions during the ETE is less well
understood than other intervals like the end-Permian mass extinction (Wignall and
Twitchett, 1996) and Jurassic and Cretaceous “ocean anoxic events” (OAEs; see review
by Jenkyns, 2010) where black shales are common and taken to represent widespread
bottom water anoxia. In particular, little is known about redox conditions in the few Myrs
leading up to the end-Triassic extinction. Black shale deposition across the Triassic-
Jurassic Boundary is regionally restricted to the Tethyan region and occurs after the ETE
rather than during or prior to the marine extinction (e.g., in the UK Hettangian Blue Lias
reported by Wignall (2001) and in Germany, reviewed in van de Schootbrugge et al.,
(2013)). Stratigraphic sections from Panthalassa are less consistent: high TOC/black
shale deposition is present at Kennecott Point (Kasprak et al., 2015; Schopefer et al.,
2016; Williford et al., 2007), but black shale and high %TOC similar to Tethys is not
recorded in other sections from Panthalassa, where %TOC either decreases (Levanto,
Peru; Yager et al., 2017) or remains low (New York Canyon, Nevada; Guex et al., 2004).
The equivocal evidence for high TOC and black shale deposition leaves open questions
about the cascade of effects operating just before the ETE, and more generally about the
Earth system response to massive volcanism. Is widespread anoxia a general signature of
such volcanism, and if so, why it its expression in the rock record apparently muted at the
ETE?
82
To address this question, here we present a new high resolution, four-million year
record of geochemical proxies for ocean redox conditions spanning the lead-up to the
ETE and the Triassic-Jurassic boundary. Our record comes from the Levanto section in
the Pucará basin of Peru, which contains a radimoetrically-constrained marine record of
the ETE and affords the opportunity to tie marine biogeochemical and redox observations
to precise timing of CAMP magmatism, based on the uniquely well defined chronology
of this marine section. Moreover, the Levanto section is from the eastern margin of
Panthalassa, providing insight into conditions in the globally most extensive ocean basin
of the time. We report nitrogen isotopes, trace metal concentrations, %N and molar C:N
from the Levanto section, and we interpret these data in terms of changing ocean redox
chemistry in the context of global environmental change and extinction at the time. Since
the ETE represents a time in Earth’s past when atmospheric pCO
2
rapidly increased,
understanding the lead up to the ETE and changes in biogeochemical and redox cycling
are vital to understanding how the earth system might respond to anthropogenic CO
2

injection.

3.2. LEVANTO SECTION AND SAMPLING
The Levanto section is comprised of thin and thickly bedded sub meter to meter
scale packages of laminated, carbonate-rich mudstones. The coarse detrital fraction (as
observed in thin sections) typically appears to be about 3% of the sample, and event beds
and turbidites are nearly absent, with the exception of one 3mm thick bed observed in
thin section (at meter 36.4). Spumellaria radiolarians are common in thin sections, and
foraminifera and sponge spicules are present in some thin sections. Ammonites and rare
83
fish bones, bivalves, and brachiopods are found in outcrop. Abundant ash beds within the
section have been U-Pb dated and together with ammonite occurrences used to define the
duration of the Rhaetian (last stage of the Triassic), and Hettangian (first stage of the
Jurassic), and to demarcate the position of the Triassic-Jurassic boundary (Guex et al.,
2012; Schoene et al., 2010; Schaltegger et al., 2008; Wotzlaw et al., 2014). The Levanto
section has uniquely well- defined chronology for a marine sedimentary section from this
time. The carbonate and organic matter rich sediments display no obvious signs of
shallowing or deepening during the continuous section, leading us to conclude the
depositional environment was relatively consistent and deep (well below storm wave
base) compared to many other Triassic-Jurassic boundary sections from which
geochemical observations are available. An absence of bioturbation and abundance of
lamination in the Levanto section suggest relatively low oxygen conditions during
sedimentary deposition. We used the age model from Yager et al., 2017 (based on U-Pb
dates from Guex et al., 2012; Schoene et al., 2010; Schaltegger et al., 2008; Wotzlaw et
al., 2014) to plot the data from this study against time.
Samples were collected approximately every half meter from the ~105 meter
continuous section (samples and powders in this study are the same as those used and
described in Yager et al., 2017). Surficial weathering and veins were avoided and cut off
when present and aliquots of samples were crushed in a jaw crusher powdered to 95%
passing through 200 mesh using mild steel grind mills. 217 of 225 samples were
evaluated for alteration and depositional environment using light microscopy and
cathodoluminescence from paired thin sections.

84
3.3. METHODS
Bulk nitrogen isotope composition was determined on 224 samples at the
University of California, Davis Stable Isotope Facility (SIF) via EA-IRMS using an
elemental analyzer (Vario EL Cube or Micro Cube elemental analyzer) interfaced to a
continuous flow isotope ratio mass spectrometer (PDZ Europa 20-20 isotope ratio mass
spectrometer). Samples were interspersed with several replicates of at least two
laboratory standards, which were previously calibrated against NIST standard reference
materials. The long-term standard deviation is 0.3‰ for
15
N at the UC Davis SIF; our
standard deviation for replicate samples was on average <0.2‰. Final delta values are
reported in per mil versus air (δ
15
N). We measured δ
15
N on the N
total
or bulk fraction,
since kerogen-only δ
15
N records may be affected by fluids from other sediments
(Svensen et al., 2008), have poor δ
15
N reproducibility (Beaumont and Robert, 1996), and
since the clay fraction of sediment may gain half of the organic N during early diagenesis
(discussed in Stüeken et al., 2016) and may retain lost N in the clay fraction (Schroeder
and McLain, 1998). In organic rich rocks like those from the section near Levanto, δ
15
N
bulk may best record the primary δ
15
N from seawater.
Trace metal concentration data were obtained via aqua regia digestion following
methods recommended for paleoredox applications by Xu et al., (2012). This digestion
selectively dissolves out primarily seawater-derived components, eliminating the need to
normalize trace metal concentrations to Aluminum or compare to average shale values.
Approximately 0.2g of powder was treated with aqua regia by reacting with a 1.6 mL of
concentrated trace-metal grade HCl for 30 minutes and then adding concentrated trace-
metal grade HNO
3
in a 3:1 volume ratio (after Xu et al., 2012). The sample in aqua regia
85
was heated in a water bath at 80-90 ºC for 2.5 hours and centrifuged to separate the
leachate from the residue. Leachates were decanted, evaporated to dryness, and
reconstituted in 1% HNO
3
. Before analysis, samples were diluted to achieve
concentrations between 1 and 10 ppb. Levels of Cd, Pb, Mo, Re, U, Co, Cu, Cr, V, Mn,
Ni, Zn were quantified by high-resolution inductively coupled plasma mass
spectrometry (HR-ICP-MS) on a Thermo Element 2 HR-ICP-MS, using external
calibration curves and an internal indium standard.
Trace metal concentrations, δ
15
N ratios, and %N data are reported in Appendix H.
We used the %TOC data from Yager et al. (2017) and %N values to calculate molar
C
org
:N
total
, hereafter referred to simply as C:N. We also include estimates of the bulk mass
accumulation rates to evaluate the role detrital fraction and sedimentary style play in
regulating metal concentration. We report correlation coefficients of each variable in
Table 1, separating the lower portion of the section (204 Ma – 201.5 Ma) and upper
portion of the section (201.51 Ma to top of section) in our division of the correlation
coefficients. We assigned ages to each sample using the age model in Yager et al. (2017),
based on U-Pb dates from ash beds (Guex et al., 2012; Wotzlaw et al., 2014). Typical age
uncertainties are on the U-Pb dates are ~150 kyrs. We report timing of changes in the
geochemical records to a precision of 10 kyrs where changes are sharply defined.

200 Ma
CAMP CAMP
Levanto
Figure 1. Triassic-Jurassic bound-
ary paleogeography with Levanto
(black star), after Kuroda et al.
(2010).
86
3.4. RESULTS
3.4.1. Nitrogen isotope and C:N ratios
Nitrogen isotope ratios, trace element concentrations, and other relevant data are
plotted as a function of time in Figures 2 and S1 and are plotted as a function of
stratigraphy in Fig S2 and S3. δ
15
N exhibits a first order shift during the Rhaetian (from ~
204 Ma to 201.5 Ma) from ~9‰ to ~2‰, remains near 2‰ until about ~200.7 Ma, and
finally shifts to 4‰ at the top of the section ( ~200.1 Ma). δ
15
N exhibits apparent
cyclicity on the order of about 2-3‰ on a ~405kyr timescale from ~204 to 202.4 Ma,
superimposed on the general declining trend in the Rhaetian. The period of cyclicity
changes to <100 kyrs at ~202.6 Ma, and cyclicity is muted after ~201.6 Ma. Weight
percent nitrogen (%N; appendix H) remains similar (0.1%) from the base of the section to
about ~201.3 Ma, followed by a decrease to ~0.05% that continues to the top of the
section, where %N varies with the amount of carbonate in the given bed (Table 1). C:N is
~13±3 at the beginning of the section, increases to an average value of ~22±3 at 203.5
Ma, remains high until 201.3 Ma, then the average value drops to 10±4.

3.4.2. Trace Metal Concentrations
Vanadium, uranium, cadmium, zinc, and to some extent chromium concentrations
exhibit increases during much of the Rhaetian, beginning at about 204 Ma. Most reach
maxima at ~201.7 Ma, and then decrease from 201.7 Ma to minima at 201.5 Ma (Fig 2;
Fig S1). The decrease between 201.7 Ma and 201.5 Ma is gradual for Zn, Cd, U (Cr
decreases earlier) and very abrupt for V. These metals largely correlate with each other in
the lower portion of the section, and to some extent with Ni (Table 1).
87
200.5 201 201.5 202 202.5 203 203.5 204
age (Ma)
0
5
10
200.5 201 201.5 202 202.5 203 203.5 204
-30
-29
-28
200.5 201 201.5 202 202.5 203 203.5 204
-2
0
2
4
200.5 201 201.5 202 202.5 203 203.5 204
0
10
20
200.5 201 201.5 202 202.5 203 203.5 204
0
200
400
600
200.5 201 201.5 202 202.5 203 203.5 204
0
20
40
60
200.5 201 201.5 202 202.5 203 203.5 204
0
20
C:N
201 202 203 204
0
2
4
U (ppm)
V (ppm)
Mo (ppm)
%TOC
δ
15
N‰
δ
13
C
org
‰
δ
13
C
carb
‰
Triassic
Rhaetian Hettangian
Jurassic ETE
Figure 2. δ
15
, δ
13
C
org
, δ
13
C
carb
,U, V , Mo, C:N and %TOC from Levanto report-
ed against time. δ
13
C
org
, δ
13
C
carb
,%TOC and age model from Yager et al., (2017).
88
Copper, cobalt, lead, and nickel concentrations are relatively stable during the
Rhaetian (although Ni increases from 201.7 Ma to 201.5 Ma) and are largely correlated
with each other (Figure S1; Table 1). Manganese concentrations are also fairly stable,
with slightly higher values at the beginning and end of the section. Molybdenum
concentrations are relatively low (average ~10ppm) through much of the Rhaetian and
increase to about 30 ppm at 201.71 Ma, remaining high until 201.48 Ma (Fig S1).
Mo, V, U (Fig 2) and Zn, Cd, Co, Cu, Ni, Pb and Mn (Fig S1) all increase in
concentration at ~200.8 Ma, and in some cases stay high until decreasing ~200.5 Ma (V,
U, Mo and to some extent Zn, Ni; Figs 2 and S1) while other metals are elevated relative
to their concentrations before ~200.8 until the top of the section (Co, Cu, Pb, Mn; fig S1).
When elemental concentrations are compared to the mass accumulation rates for
the detrital fraction, no correlation is observed from 204.2 Ma to 201.5 Ma for redox
sensitive trace metals (Table S1). During the upper portion of the section (201.5 Ma to
200 Ma) the estimated mass accumulation rate of the detrital fraction (MAR
detrital
)
accounts for much of the variation seen in Pb, Cr, V, %TIC, %N and to a lesser extent
Zn, Co, Cu, Mo (Table S1; discussed further in S4).
We also used thin section analyses to gain a qualitative presence/absence analysis
of radiolarians found in thin section. Radiolarians are present in most thin sections from
the bottom of the section to 201.47 Ma. No radiolarians are found between 201.47-201.29
Ma, and are rare until 200.73 Ma, when radiolarians reappear and persist from 200.73 Ma
to the top of the section.

89
3.5. DISCUSSION
3.5.1 Orbitally-forced cyclicity in δ
15
N at the Levanto section during the Late
Triassic
The marine nitrogen cycle couples atmospheric CO
2
, nutrient delivery, and
primary productivity in the ocean and atmosphere systems. During its biogeochemical
transformations, stable isotopes of N are fractionated, with fractionation factor ε
characteristic of different processes. Fixed nitrogen enters the ocean via nitrogen fixation
(ε=≤2‰) and can be taken up and during primary productivity (ε=~5‰) and
remineralization (ε=~5‰) (e.g. Sigman et al., 2009). Fixed nitrogen leaves the available
pool in the ocean during denitrification, either in oxygen minimum zones (localized;
ε=25‰) or in sedimentary denitrification (within sediments, effectively ε=0‰). Water
column denitrification leaves a heavy isotopic signal on the leftover pool of dissolved
nitrate, which mixes into the global ocean. The production and utilization of dissolved
organic nitrogen is also important in nitrogen cycling, but not well constrained
isotopically (Sigman et al. 2009). δ
15
N thus records information regarding oxygenation
within the water column and sediments, primary productivity, and biogeochemical
cycling on local and global scales (e.g., Sigman et al., 2009; see S1 for more detail). In
today’s ocean, the sum of N sources and sinks yield an average oceanic nitrate value of
~5‰ per mil (Sigman et al. 1997). Inherent in our interpretation of sedimentary N is that
the signal recorded is one of surface ocean nitrate, which generally reflects global ocean
nitrate (Altabet et al., 1999). In nearshore environments like that inferred from Levanto,
the primary signal on nitrate in the sediments is via denitrification intensity (e.g. Hendy et
al., 2004).
90
-30
-29
-28
-27
-4
-2
0
2
4
age (Ma)
0
5
10
0
20
40
0
200
400
600
0
2000
4000
6000
201 202 203
δ
15
N‰
pCO
2
δ
13
C
org
‰ δ
13
C
carb
‰
reef gap
C. marshi P. planorbis A. lias.
Triassic Jurassic
Hettangian Rhaetian
ETE
Time (Ma)
Ammonite biozone
Radiolarians
Reef absence
benthic sponges
Black shales (Tethys)
Global Anoxia
CAMP U-Pb
Mo (ppm) V (ppm)
91

The Rhaetian δ
15
N values near 9‰ and cyclicity of approximately 2-3‰ (Fig 2)
may reflect a dynamic oceanic nitrogen cycle during the latest Triassic that resembles the
recent ocean. Between glacial and interglacial intervals, oceanic δ
15
N shifts with heavier
δ
15
N during interglacial periods due to relatively larger oxygen minimum zones and
increased denitrification. Glacial intervals have lighter δ
15
N due to smaller oxygen
minimum zones and decreased denitrification (e.g., Ganeshram et al., 2000; Galbraith et
al., 2008; Altabet et al. 1999 and see S1). We invoke a similar mechanism of expansion
and contraction of oxygen minimum zones through time imparting more and less
denitrification to explain the cyclicity observed in the Levanto section. Cycles occur with
a periodicity of approximately 405 kyr during much of the Rhaetian, corresponding to the
dominant orbital cycle during the Late Triassic (Kent et al., 2016). Although it is unlikely
that cyclicity observed in the Rhaetian is due to glacial/interglacial cycles, sea level
fluctuations (Lau et al., 2016; Bachan et al., 2017) or some other orbital forcing of ocean
system may have impacted the expansion and contraction of OMZs.

3.5.2 Increasing ocean oxygenation in the lead up to the end-Triassic extinction
In summary, we suggest that the regular cyclicity seen at Levanto, like that seen
in more recent and well understood oceans (such as the Pleistocene), corresponds to the
Figure 3 (previous page). rom eanto Peru section δ
13
C
org
δ
13
C
carb
from
(ager et al. 201) δ
15
N, Mo, and V (this study) (3-pt moving averages); pCO
2

estimates (Schaller et al., 2014; 2011); CAMP ages (Davies et al., 2017); radiolari-
an occurences (this study); ammonite biozones (Guex et al., 2012; Yager et al.,
2017); reef presence/absence (Martindale et al., 2015); benthic sponge occurence
(Corsetti et al., 2015; Ritterbush et al., 2014); black shale deposition (Tethys; van
de Schootbrugge et al., 2013); global anoxia from U isotopes (Jost et al., 2017).
92
increasing oxygenation,
small OMZ
less reducing sediments
U, V
δ
15
N
δ
13
C
org
CIE
High pCO
2
High pCO
2
local euxinia
anoxia
expanded OMZs
and reducing sediments
U, V
203.5 Ma
405 kyr
201.7 Ma
A
B
C
U, V
δ
15
N
Levanto
Levanto
Global
CAMP
CAMP
Elsewhere
δ
15
N
U, V, Mo
U, V, Mo
δ
15
N
increasing oxygenation,
small OMZ
less reducing sediments
U, V
D
U, V
δ
15
N
Levanto Global Elsewhere
U, V
δ
15
N
Global
Levanto Global
Elsewhere
Elsewhere
Figure 4 . Representations of events surrounding Triassic-Jurassic boundary.
Late Triassic (~204 to 201.6 Ma)
ETE (201.51 -201.36 Ma)
Early Jurassic (~201.36 - 200.8 Ma)
Early Jurassic (~200.8 - 200 Ma)
93
expansion (heavy δ
15
N) and contraction (light δ
15
N) of oxygen minimum zones during
the orbitally-forced cycles during the late Triassic. By analogy, the simplest explanation
for the longer-term shift from ~9‰ to 2‰ in δ
15
N during the Rhaetian may be a
sustained decline in the degree of water column denitrification over time, reflecting a
sustained reduction in the extent of oxygen minimum zones (OMZs) and an increase in
oceanic oxygenation.
This trend in δ
15
N is not unique to the Levanto section, other records of δ
15
N from
the Triassic-Jurassic boundary interval suggest the late Rhaetian shift may be a global
signal (Fig S4). δ
15
N records from Kennecott Point (Schoepfer et al., 2016; Kasprak et
al., 2015), the Mingolsheim Core, Germany (Quan et al., 2008; van de Schootbrugge et
al., 2008), the Marinetal core, Germany (Richoz et al., 2012), Doniford Bay, UK (Paris et
al., 2010), and previously unpublished data from New York Canyon, Nevada (this study;
see Appendix H) all span the late Triassic and early Jurassic. In four of these five records,
δ
15
N decreased during the late Triassic, suggesting that the trend towards lighter nitrogen
isotopes was widespread, both in the Tethyan and Panthalassic Oceans. Globally
decreased denitrification within oxygen minimum zones (OMZs) could explain this late-
Rhaetian δ
15
N decrease across multiple sites. We acknowledge other possible
mechanisms could have affected δ
15
N in sediments and globally in the ocean at this time
(discussed in detail in S2 and S3), but we think changes in global extent of oxygen
minimum zone based denitrification offer the most likely explanation.
Helping to corroborate this interpretation, trace metal concentrations from
Levanto also suggest shrinking OMZs through time in the late Triassic. Redox-sensitive
metals that are thought to largely accumulate in anoxic sediments, in particular V and U
94
(Fig 2), as well as Cd and Zn (Fig S1), increase in concentration in the samples from
Levanto in tandem with the Rhaetian δ
15
N decrease from ~204 Ma to ~201.7 Ma. V and
U are both conservative in the ocean and thought to have principal sinks in reducing
sediments. Thus a reduction in the extent of anoxic sediments, e.g. associated with
shrinking oxygen minimum zones, would increase the concentration of these metals in
the ocean. Assuming no major change in the oxygenation at the sediment-water interface
at Levanto through our studied interval and presuming anoxic conditions at this site
through the Rhaetian (as suggested by the consistently laminated sedimentation) the
observed increase in V and U concentrations may reflect a global increase in the seawater
concentrations of these elements through the Rhaetian. Thus the trace metal
concentrations corroborate our interpretation of the δ
15
N record as reflecting increasing
global oxygenation in the late Triassic (see Figure 4A for schematic). Although the
records of V and U most convincingly support this interpretation of δ
15
N, Zn and Cd are
broadly similar, with differences that may be attributed to differences in redox chemistry
during deposition and diagenesis or residence time in the ocean (e.g., Little et al., 2015;
Tribovillard et al., 2006).
Another potential explanation for an increase in trace metal concentrations
through the Rhaetian is a potential decrease in oxygenation in the local environment.
Since we do not observe corresponding changes in bioturbation, we do not think this is
the dominant control on the δ
15
N or trace metal trends in the Rhaetian. However, we
discuss possibilities of local changes in redox and their affects on δ
15
N and trace metal
concentrations in detail in S3.

95
3.5.3. A modern style nitrogen cycle during the Late Triassic
δ
15
N records during “greenhouse intervals” of the Phanerozoic are generally
characterized by low values (-4 to -1‰; Algeo et al., 2014), much lower than modern or
recent values, or indeed the values we observe in the Late Triassic from Levanto and
other Triassic-Jurassic boundary sections (Fig S4). The nitrogen isotope records from
greenhouse intervals may be explained by dominance of ammonium recycling in
greenhouse oceans (Algeo et al., 2014). The Triassic-Jurassic boundary is typically
regarded as pervasively greenhouse, yet our data from Levanto fall between 9‰ and 2‰,
more positive than other Phanerozoic greenhouse intervals. The coherent changes in both
N isotopes and trace metals support our data as reflecting modern style N cycle linked to
ocean oxygenation.
Records from the compilation showing light δ
15
N during greenhouse intervals
include abundant samples deposited in epicontinental seaways, which may not be
representative of all greenhouse oceans. In contrast, the Levanto δ
15
N record is from the
eastern margin of Panthalassa, and the depositional environment and δ
15
N results are not
altogether dissimilar to borderland basins off the coast of Southern California today (e.g.
Altabet et al., 1999; Tems et al., 2015), which may suggest a similar N cycle as the
modern and recent ocean operating in the Late Triassic. Alternatively, the discrepancy
between greenhouse climate state nitrogen cycling and Triassic-Jurassic boundary
records could indicate the Late Triassic may not have been characterized strictly by a
greenhouse climate. Decreasing pCO
2
during the Rhaetian (Schaller et al., 2014; Schaller
et al., 2011) and brief icehouse stages in the Early Jurassic (late Pleisbachian; e.g. Korte
and Hesselbo, 2011) support the idea of a more dynamic climate system that simply
96
greenhouse. Many of the published records from greenhouse oceans are focused right
around boundary events, and more nitrogen isotope data from intervals like the Late
Triassic may help untangle these questions. The Levanto record may indicate a more
similar nitrogen cycle operating during the Late Triassic than previously understood.

3.5.4. Rapid drop in oxygen: Onset of local marine euxinia at the time of extinction
and globally pervasive anoxia that follows
The gradual trends in δ
15
N and trace metal concentrations through the Rhaetian
are interrupted between 201.7 and 201.5 Ma, before the end-Triassic extinction. Mo
concentrations increase from ~10ppm to ~35ppm abruptly at 201.71 Ma, coincident with
a decline in U and to some extent Cd and Zn concentrations. Mo decreases to ~10ppm at
201.47 Ma, just after the abrupt V decrease at 201.49 Ma. The Mo concentrations ~35
ppm between 201.71 Ma and 201.48 Ma are similar to those seen in euxinic basins today
(e.g., Lyons et al., 2009; Scott and Lyons, 2005 and references therein) and may reflect
an abrupt and sustained onset of euxinia at the Levanto section for 250 kyrs, since high
Mo is indicative of H
2
S and euxinic conditions in most marine settings (Lyons et al.,
2006; 2009). δ
13
C
org
at Levanto increases to ~-28‰, remaining elevated from ~201.7 Ma
to 201.56 Ma, largely in association with high Mo concentrations (Fig 4B for schematic).
At 201.58, coincident with the last occurrence of C. crickmayi, δ
13
C
org
drops
rapidly, and this negative carbon isotope excursion marks the onset of the ETE based on
the last occurrence of C. crickmayi. The δ
13
C
org
negative excursion begins within the zone
of elevated Mo concentrations and ends with Mo concentrations back down at ~10 ppm
at ~201.5 Ma. By this time, the redox-sensitive trace metals (e.g., U, V in addition to Mo)
97
are at local minima, suggesting an expansion in the global extent of reducing sediments
and therefore ocean anoxia (Fig 4C for schematic). Though the first-order features are
similar for δ
15
N and the redox-sensitive trace metals, there are subtle differences between
the metals. In particular, U concentrations decrease gradually beginning at 201.8 Ma or
201.7 Ma, while V concentrations drop abruptly at 201.49 Ma. These differences may
reflect subtleties in the redox chemistry of the different metals.
Thus we interpret the Levanto trace metal record to indicate locally euxinic
conditions (high Mo concentrations) in the ~150 kyrs prior to the extinction, when δ
13
C
org

shows a positive excursion, followed by global expansion in anoxia coincident with the
ETE and negative δ
13
C
org
excursion. The rapid trace metal drawdown seen at 201.50 Ma
is temporally indistinguishable from the termination of the negative CIE, which suggests
the negative CIE preceded a globally significant expansion in anoxia. The gap in
radiolarians seen in thin section coincides with the interpreted globally extensive anoxic
interval from 201.47 to 200.73 Ma (Fig 3).
Other evidence from Levanto is consistent with the interpretation of anoxic
conditions at the time of the extinction. Nitrogen isotopes reach a consistent value ~2.5
‰ beginning around 201.7 Ma, continuing into the Hettangian, and cyclicity in δ
15
N
gradually diminishes and is effectively absent from ~201.3 Ma onward. Photic zone
euxinia might be one plausible explanation for the light δ
15
N, and the end to the cyclical
variation, because euxinia could lead to dominant N
2
fixation nitrogen cycle (Boyle et al.,
2013; Stüeken et al., 2016) and thus impart a light isotopic effect locally. Interestingly,
while C:N values eventually decrease during the Hettangian at Levanto (after 200.8 Ma),
98
they do not immediately drop during this interval, as might be expected for dramatically
altered N cycle that is dominated by N fixation.
Given the diminished presence of radiolarians from 201.56 until 200.8 Ma at the
Levanto section, the upper ocean C cycle does not appear to support radiolarian growth
and likely reflects a stressed upper ocean. This is concomitant with low δ
15
N, and may
suggest a muted nitrogen cycle at Levanto during this time.

3.5.5. Cessation of ocean anoxia at ~200.8 Ma
Mo, V, U (Fig 2) and Zn, Cd, Co, Cu, Ni, Pb and Mn (Fig S1) all increase in
concentration at ~200.8 Ma, and in some cases stay high until ~200.5 Ma and in others
remain elevated at Levanto. We interpret this increase as a dramatic re-oxygenation event
of the global oceans, which likely reoxygenated some marine sediments where trace
metals found a sink and resuspended them in the ocean, to be pulled out in anoxic
settings such as the section preserved near Levanto. Locally, this coincides with the
reappearance of radiolarians in thin section and a shift towards more positive δ
15
N values.
Using ammonite biozones as a correlation tool, this also coincides with the end of the reef
gap (Martindale et al., 2015), shallow benthic sponge appearance in shallow marine
sections (Ritterbush et al., 2014; 2015), with a major ammonite radiation (Guex et al.,
2012) and with a decrease in atmospheric pCO
2
(Schaller et al., 2014; Fig 3).

3.5.6. Increasing oxygenation increases perturbation susceptibility
Evidence for anoxia and euxinia has been observed in other Triassic-Jurassic
boundary sections. Photic zone euxinia, coincident with the end-Triassic extinction, has
99
been documented from Panthalassa at Kennecott Point using biomarkers (Kasprak et al.,
2015; Schopefer et al., 2016). In the German Mariental core, an isorenieratane peak
immediately after the negative CIE was interpreted as indicative of photic zone euxinia in
Tethys (van de Schootbrugge et al., 2013). Many Tethyan sections are characterized by
low TOC during the Triassic and high TOC during the Early Jurassic (e.g., Hesselbo et
al., 2004; van de Schootbrugge et al., 2013), which has been suggested as indicative of
widespread anoxia (leading to greater OC preservation) immediately after the Triassic-
Jurassic boundary. Jost et al. (2017) reported δ
238
U isotopes through the Triassic-Jurassic
boundary in the Italian Val Adrara section and observed a 0.7‰ negative excursion in
marine carbonates just above the TJB, which they attribute to a 40-100 fold expansion in
anoxic U deposition during the earliest Jurassic. Based on C isotope correlation, this
δ
238
U excursion is coincident with the onset of anoxia at the Levanto section from our
interpretations of low trace metal concentrations between 201.56 and 200.8 Ma. These
geographically widespread records thus point consistently to a change in marine
oxygenation, and the coincident timing with the end-Triassic extinction raises the
possibility that the drop in marine oxygen may have been the extinction trigger.
We infer globally increasing oxygenation of the marine realm in the period of
time prior to CAMP volcanism and the ETE, based on the shift towards lighter δ
15
N and
increased V and U. We suggest that the Earth system may have entered the ETE with a
relatively larger aerial extent of oxygenated areas in the ocean, which may have increased
the susceptibility of the Earth System to perturbation. If CO
2
drawdown was associated
with this increase in oxygenated areas of the ocean, then CAMP CO
2
release may have
had a more severe effect relative to other Mesozoic events due to the lower starting point.
100
We speculate that the lack of black shale deposition, especially in sections from
Panthalassa at the time, may reflect less severe anoxia than experienced during other
intervals such as the end-Permian, but the high oxygen before may have made this event
still severe. In that regard, this interval may provide a more relevant comparison to the
modern, when the oceans are relatively well oxygenated and expected changes are
unlikely to lead to pervasive black shale deposition but may still have severe
consequences on marine life (e.g. Moffitt et al., 2015).

3.5.7. CAMP and the ETE
In Figure 3, we summarize our data and other globally significant data spanning
the Triassic-Jurassic Boundary. Atmospheric pCO
2
estimates (Schaller et al., 2014;
Schaller et al., 2011) and declining sea surface temperature (SST) estimates (Knobbe and
Schaller, 2018) suggest a drawdown in atmospheric pCO
2
and SST before CAMP
emplacement, while δ
13
C
carb
increases (Yager et al., 2017), δ
15
N decreases, and trace
metal data suggest increasing oxygenation in the ocean (this study), all prior to the oldest
CAMP U-Pb dates (Fig 3, Davies et al., 2017). Schaller et al. (2014) attributed the
drawdown of atmospheric pCO
2
to the northward migration of Pangea and enhanced
silicate weathering. The oxygenation we hypothesize based on the Levanto record occurs
in tandem with decreasing pCO
2
and temperature, while δ
13
C
carb
increases. We speculate
that with decreasing pCO
2
, increasing continental weathering, and declining
temperatures, thermohaline circulation may have increased, upwelling more nutrients and
burying more organic carbon, leading to increased δ
13
C
carb
and a reduction in the extent
of water column oxygen minimum zones. Low oxygen is the most plausible way to bury
101
and preserve more organic matter, so the apparent coincidence of increasing oxygenation
and increasing Corg burial is somewhat enigmatic. However, on long timescales organic
C burial is the primary process associated with oxygen release and δ
13
C enrichment.
Reconfiguration of basins could plausibly change the amount of organic carbon burial.
Additionally, the Triassic-Jurassic boundary marks a major change in the carbonate and
silica cycles, with the evolution of planktonic foraminifera and diatoms hypothesized to
have occurred during this interval with dramatic consequences for the carbonate cycle
(e.g. Ridgwell 2005). We speculate that the ballasting of organic matter during sinking of
new carbonate and silica producers would also bury more organic matter and possibly
increase oxygenation.
We can make several other comparisons between data from Levanto, CAMP
absolute ages, and existing Triassic-Jurassic boundary records using biostratigraphy and
chemostratigraphy (Fig 3). 1) The earliest CAMP ages from U-Pb dating
(201.635±0.029, Davies et. al., 2017; Fig. 3) occur during the positive shift in δ
13
C
org
and
inferred euxinic interval at Levanto. 2) At ~201.56 Ma the last Triassic ammonite (and
marker for marine extinction), negative δ
13
C
org
excursion, and beginning of decline in
trace metals from Levanto occurs – using C isotope correlation, this coincides with a
negative excursion in U isotopes, indicative of global anoxia (Jost et al., 2017); this is
rapidly followed by trace metal drawdown at Levanto. This is all associated with high
pCO
2
~201.5 Ma, likely due to CAMP magmatism (Schaller et al., 2014).
We speculate local euxinia at Levanto coincided with CAMP magmatism, and
was followed by a rapid expansion in anoxia that was globally significant. The anoxic
interval’s co-occurrence with the negative δ
13
C
org
excursion may suggest anoxia played a
102
role in the δ
13
C
org
CIE (perhaps due to a change in the type of organic matter preserved,
Ruhl et al. 2010 or the contemporaneous release of methane during clathrate release, e.g.
Hesselbo et al. 2004). This expansion in anoxia is contemporary with the reef gap and
marine extinction (Fig 3) and absence of radiolarians in the Levanto section. Following
the end of CAMP magmatism, CO
2
begins to decline and is associated with a potential
global increase in oxygen that occurs around 200.8 Ma, during the Planorbis ammonite
zone. This is somewhat coincident with the drawdown of CO
2
(Schaller et al., 2014), the
conclusion of the carbonate “reef gap” (Martindale et al., 2012), and reappearance of
radiolarians at Levanto.

3.6. CONCLUSIONS
We report the first high-resolution δ
15
N and trace metal record spanning four
million years of the Late Triassic and Early Jurassic with robust temporal constraints,
enabling a detailed examination of biogeochemical cycles and redox conditions before,
during, and after CAMP emplacement and the end-Triassic extinction. Taken together,
we suggest the δ
15
N and trace metal results from Levanto, taking into consideration other
available δ
15
N records from the Triassic-Jurassic boundary, suggest decreasing oxygen
minimum zone extent through the Late Triassic, which likely involved the interplay
between decreasing atmospheric pCO
2
(Schaller et al., 2014), increasing thermohaline
circulation, and enhanced burial and preservation of organic matter (Yager et al., 2017).
This may reflect a cooler Late Triassic world than typically thought, and one with a
nitrogen cycle similar to the modern ocean, one forced by orbital cycles on the order of
405 kyr. At the onset of CAMP volcanism, organic carbon isotopes shift towards positive
103
values while some metals from the Levanto record begin to decrease in concentration
(e.g. U); soon after, Mo concentrations rise, reflecting local euxinia at the Levanto record,
while δ
15
N ceases to change and exhibits little cyclicity, likely due to the presence of
euxinia leading to a nitrogen fixation dominated nitrogen cycle at this location. The end-
Triassic extinction occurs within this euxinic interval. At the termination of the negative
CIE in organic carbon isotopes and in conjunction with the Triassic-Jurassic boundary,
trace metal concentrations indicative of global redox conditions fall to minima,
suggesting a rapid expansion in ocean anoxia, and supported by widespread anoxia found
in early Jurassic waters from Tethys (e.g. Schootbrugge et al., 2013; Jost et al., 2017). It
is possible that increasing marine oxygenation in the late Triassic may have pre-disposed
the oceans and atmosphere to CAMP perturbation that was more significant because of
the relatively low atmospheric pCO
2
beforehand.

104
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115
3S. SUPPLEMENTAL INFORMATION FOR CHAPTER 3
3S1. The marine N cycle and isotopic fractionation
The marine biological pump is a key modulator of atmospheric pCO
2
and a
primary link between the nitrogen and carbon cycles (Sohm et al., 2011). In the modern
ocean, nitrogen sources, sinks, and recycling processes impart isotopic fractionation that
is transferred to sediments (see review by Sigman et al., 2009). Nitrogen isotopes (δ
15
N)
can be preserved in marine sediments and yield information about the nitrogen isotope
ratio of nitrate in the water mass and aspects of biological processes that cycled nitrate in
the water column (e.g., Prokopenko et al., 2006). The main source of fixed nitrogen (the
biologically available form, predominantly nitrate) in the ocean is N
2
fixation by
diazotrophs (mostly cyanobacteria) in the photic zone (Sohm et al., 2011). N
2
fixation
imparts little to no fractionation (-1‰ to 1‰) from atmospheric nitrogen (air defined as
0‰) and occurs where nitrate is limiting (Sigman et al., 2009). Denitrification is the
dominant sink for fixed nitrogen and occurs in areas where oxygen is too low to support
oxygenic respiration, such as in localized oxygen minimum zones, or OMZs.
Denitrification preferentially removes light nitrate and leaves behind a pool of heavy
δ
15
N that can reach up to 25‰ in OMZs (Sigman et al., 2009). Where denitrification is
complete (within marine sediments) and utilizes the entire pool of available nitrate in
pore water, it results in no net isotopic effect due to complete consumption of the
available N. Fixed nitrogen removal in localized OMZs leaves heavy residual nitrate in
the watermass, which mixes with other fixed nitrogen in the ocean, imparting a heavier
signal on the average global ocean nitrate, today ~5‰ (Sigman et al., 2009). Over time,
the average δ
15
N of seawater nitrate is closely associated with the degree of oxygenation
116
in the ocean because the extent of oxygen minimum zones controls the extent to which
denitrification imparts a heavy isotopic signal on water masses. Local effects can also
leave an imprint on the N isotope composition of seawater at a given site. Nitrate uptake
(biological utilization) by phytoplankton other than diazotrophs and up through the food
web also imparts a slight isotopic effect with ε of 5‰. Remineralization of organic matter
typically has an ε of <5‰ (Sigman et al., 2009).
Considering all of these isotope effects, records of δ
15
N from marine sediments in
deep time can therefore yield information about a combination of biogeochemical cycling
in a specific region (i.e., in the water column overlying the sediments) as well as the
average redox state of the paleo ocean. Measurements of bulk nitrogen isotopes (δ
15
N
bulk

or δ
15
N
total
) from marine sedimentary rocks record a combination of the isotopic value of
the pool of nitrate in the overlying water mass, the δ
15
N value of marine NO
3
-
from
overlying primary production, the remineralization of sinking organic matter-associated
nitrate, early diagenesis associated with deposition and remineralization in pore water
reactions, and any post depositional diagenesis (e.g., Algeo et al., 2014; Ader et al., 2016;
Stüeken et al., 2016). It is possible that changes in each of these processes could have
affected the δ
15
N record from Levanto, and different possibilities are explored in detail in
this Appendix along with an explanation of reasons why we think most of these
alternative explanations are less likely than those presented in the main text.

117
3S2. Alternative explanations for a Rhaetian shift in sedimentary δ
15
N at Levanto
3S2.1. Shift in proportion of sedimentary denitrification
We interpreted the Levanto δ
15
N record as reflecting decreasing denitrification
within oxygen minimum zones. An alternative explanation could be an increase in the
proportion of sedimentary denitrification in the ocean, relative to that taking place in
oxygen minimum zones (e.g., Stüeken et al., 2016), which would decrease the overall
isotopic signature of δ
15
N in the ocean. Increasing sedimentary denitrification would
require increasing the amount of shallow sediment covered by water, e.g., by raising sea
level. However, we think this explanation is unlikely on the basis of most sedimentary
sections across the Triassic-Jurassic boundary exhibiting sea level low stands, which
would decrease the amount of shelf area available for sedimentary denitrification.

3S2.2. Shift in nitrate utilization
Incomplete utilization of nitrate by phytoplankton in surface waters could also
impart a shifting δ
15
N signature through the Rhaetian. Nitrate uptake preferentially
incorporates isotopically lighter N in biomass, leaving behind a heavier pool of δ
15
N.
When nitrate is readily available, the pool does not get heavily exploited and the δ
15
N of
organic matter preserved in sediments remains isotopically light. When a larger fraction
of available nitrate is exploited, nitrate in organic matter is heavier since a larger fraction
of the pool is used (following Rayleigh-like fractionation). One possible explanation for
the shift in δ
15
N from 9 to 2‰ through the Rhaetian at Levanto could be that the relative
fraction of used nitrate during the early Rhaetian was greater than in the late Rhaetian.
This could arise via 1) increased nitrate supply through time or 2) decreased nitrate
118
uptake in the surface ocean community at this locality. If the shift represents an increase
in nitrate supply, we might expect %TOC and other productivity proxies to increase as
well, reflecting more productivity and preservation of organic matter. If instead nitrate
utilization decreased through time (assuming the same nitrate supply), we would expect
lower productivity reflected by lower %TOC exported to the sediments. However, no
correlation is observed between δ
15
N and %TOC during the Rhaetian (Fig. 1), so it seems
unlikely that a same-sized nitrate pool is being exploited less through the Rhaetian, or
that an increase in nitrate supply is the cause of the δ
15
N shift. Furthermore, Nickel and
Copper, metals that may be interpreted as indicative of organic C sinking flux
(Tribovillard et al., 2006) do not change during the Rhaetian (Fig. S1), suggesting no
change in nutrient delivery and productivity, and providing further evidence to reject
nitrate supply driven change in δ
15
N.

3S2.3. Shift towards nitrogen-fixation dominated community
The Rhaetian shift in δ
15
N values could also be explained by a shift from a
community that is not nitrate-limited to one that is limited by nitrate and whose fixed
nitrogen inputs become dominated by nitrogen fixation. Nitrate-limited communities
typically occur in regions with low nitrate, since nitrogen fixation is inhibited by the
presence of nitrate. If the first order shift in δ
15
N were a signal of increased nitrogen
fixation through time, we would expect a lower C:N trend through the same interval,
reflecting the composition of nitrogen fixers (which have a lower C:N ratio), and we
would expect a decrease in %TOC through time, reflecting a decrease in productivity due
to nitrate limitation in the area. Instead we observe steady C:N and %TOC values through
119
the Rhaetian (Fig. S2), so it seems unlikely that the first order shift in δ
15
N is due to a
shift towards dominance of nitrogen fixation.
Schoepfer et al., (2016) attributed the late Triassic shift towards lower δ
15
N values
seen at Kennecott Point (Fig S4) as indicative of a transition from a greenhouse state
(ammonium recycling dominated) ocean to a N
2
fixation dominated ocean. A more
plausible explanation from our record is that in association with the end-Triassic
extinction and onset of euxinia, the normal marine nitrogen cycle was unable to continue
and became N
2
-fixation dominated.

3S3. Diagenetic, depositional environment, and oxygen exposure time
Nitrogen isotopes in any sedimentary record may also be impacted by changes in
(1) local OMZ size, shape, and placement, (2) sedimentary diagenesis, and (3)
winnowing and sediment removal. Here, we discuss some of these possibilities and data
to support or reject them.

3S3.1. Changes in marine and continental-derived fractions
δ
15
N values in sedimentary records may change based on the inputs from
continental versus marine-derived organic material. Terrestrial organic matter (δ
15
N
~2‰) is typically isotopically lighter than marine organic matter (δ
15
N ~10‰) (Sweeney
and Kaplan 1980). δ
15
N values observed during most of the Rhaetian (average 5.7‰, but
shifting to lighter values) may suggest a shift towards more terrestrially derived organic
matter. However C:N values can also help determine the marine vs. terrestrially derived
organic matter source, with terrestrial organic matter typically having C:N ratios from 20-
120
70 (Meyers et al., 1994) and marine organic matter near 10, reflecting the dominance of
marine algae (Meyers et al., 1994). C:N ratios at Levanto change during the Rhaetian but
are near 20 (Fig. S2), which could reflect a combination of terrestrial and marine organic
matter input, but C:N has a correlation coefficient of 0.13 with δ
15
N for this interval
(Table S1), so it is unlikely that the first order shift in nitrogen isotopes is due to
changing proportions of terrestrial matter input through time.
MAR
detrital
also has no relationship with δ
15
N (r
2
=0.03; Table 1), making
systematic change of terrestrially-derived organic matter unlikely (since this should
accompany a change in the estimated detrital material as reflected in MAR
detrital
). Again,
this suggests that increases or decreases in terrestrial input are not the primary control on
the δ
15
N record. Also, no corresponding change in sedimentology or fossil occurrence
accompanies the Rhaetian shift in δ
15
N. We therefore conclude that the δ
15
N shift from
9‰ to 2‰ during the Rhaetian is not predominantly controlled by a secular change in the
proportion of terrestrially-derived organic matter.

3S3.2. Changes in bottom water oxygenation and their diagenetic effects on δ
15
N
δ
15
N
bulk
and δ
15
N
chlorin
(the N isotopes in a specific biomarker) from the modern
Peru margin suggest that anoxic organic matter degradation results in lighter δ
15
N
bulk

values whereas δ
15
N
chlorin
values are resistant to these changes (Junium et al., 2015). At
Levanto, it is possible that heavy δ
15
N values observed in the earliest part of the Levanto
section (~9‰ around 203.5 Ma) reflect the impingement of the core of an OMZ on the
sediments, with the extent moving laterally or vertically through time, in which case the
light or lightest δ
15
N values during the Late Triassic may be due to a slow migration of
121
the OMZ through time and degradation during transport or increased oxygen exposure
time of organic matter. In other studies detailing this affect, winnowed sediments were
apparent and larger grain sizes evident (e.g., Junium et al., 2015). We do not observe
winnowed sediments or other evidence of sedimentary transport during the Rhaetian at
Levanto, but it is possible that different oxygen exposure times at the sediment water
interface or transport before deposition of organic matter could have generated altered
δ
15
N signatures.
If δ
15
N values from ~ 202.5 Ma (6‰) through 201.5 Ma (2‰) reflect a change in
δ
15
N degradation via the local shift of an OMZ, with increasing degradation through
time, this suggests a longer oxygen exposure time at the sediment-water interface and we
would expect changes in trace metals to decrease instead of increase and for organic
matter preservation to decrease (it does not). Additional measurements, including
compound specific measurements of δ
15
N, are beyond the scope of this study, but might
be considered as possible additional tests. However, absent corresponding changes in
%TOC preservation, bioturbation, and indicators of winnowed sediments, a migrating
oxygen minimum zone does not seem the simplest explanation for this dataset.
In other settings, oxic diagenesis has been observed to increase bulk δ
15
N by ~4‰
(reviewed in Stüeken et al., 2016; Altabet et al., 1999; Freundenthal et al., 2001; Lehman
et al., 2002) whereas anoxic diagenesis imparts minor isotopic fractionations (<1‰). So,
a change from oxic to anoxic diagenetic conditions could also have produced the
observed change in δ
15
N through the Rhaetian. However, again, in the absence of
corresponding changes in %TOC, bioturbation, or indications of winnowed sediments,
122
we do not think a change in the oxygenation at the sediment water interface is the
primary control on the δ
15
N shift from 9‰ to 2‰.

3S3.3. Changes in δ
15
N during sinking and remineralization
Remineralization and diagenesis may drive changes in δ
15
N values, as well as
changing trace metal accumulation (or re-suspension). Preferential degradation of
isotopically depleted nitrate may cause fractionation during sinking and remineralization
of organic matter, with an up to 4‰ isotopic offset between the sinking flux and that
preserved in sediments (e.g. Altabet and McCarthy, 1985). This is most common in deep
pelagic ocean basins and is unlikely to be the primary signal at Levanto, which was much
shallower. In this higher productivity region where preserved %TOC is high, we assume
water column remineralization was incomplete and fractionation during sinking not the
major signal translated from the surface ocean to the sediments (e.g. Altabet et al., 1999).
The high C:N ratio observed during the Rhaetian is likely due to the preferential
degradation of labile organic matter, such as proteins and nucleic acids, which are major
N-bearing compounds. In areas of high productivity, enhanced degradation of N-rich
compounds increases (Twitchell et al., 2002) which could be the source of high Rhaetian
C:N values. This is especially likely during the Rhaetian at Levanto given the high
%TOC preservation, which could reflect relatively high productivity. However, this
preferential degradation of N-rich compounds is unlikely to have similarly impacted δ
15
N
because there is little correlation between C:N and δ
15
N (Table 1).
Increased C:N values are also likely influenced by progressive burial during early,
pore-water driven diagenesis, since preferential degradation continues, but this is also
123
unlikely to have affected δ
15
N (Ganeshram et al. 2000). In organic-rich, non deep water
settings, early diagenesis preserves δ
15
N and does not shift sedimentary nitrate values
more positive (Ganeshram et al., 2000). Nitrate is typically completely consumed during
early diagenesis, with little fractionation occurring during these pore water reactions and
sediments typically record the water column δ
15
N value to within ~1‰ (e.g., Prokopenko
et al., 2006) due to near complete utilization of pore water nitrate (Sigman et al., 2003).
The leftover residual nitrogen may then get adsorbed onto the clay fraction. This
motivates running bulk and not simply organic nitrogen for analyses of δ
15
N in marine
rocks (see Ader et al., 2016 and Stüeken et al., 2016). During later burial, no systematic
change in C:N or δ
15
N is expected (see review by Ader et al., 2016).
Taken together, we interpret the high C:N values observed during the Rhaetian as
likely influenced by early remineralization and metabolism of organic matter during the
earliest stages of burial history, which likely did not systematically affect δ
15
N values.

3S4. Detrital fraction and potential dilution of trace metals
In any measured sedimentary section, geochemical signals are a mix of local and
global signals. Our view is that leading up to the end-Triassic at Levanto, factors such as
sedimentation rate and carbonate dilution do little to explain changes in isotope ratios and
trace metals, while during the Hettangian some results at this section can be explained by
changes in the estimated detrital input.
We also considered the impact of the fraction of carbonate (e.g. in terms of
diluting trace metal inventories) on the concentration data (calculating % on a carbonate-
free basis ‘CFB’), and the impact of mass accumulation rates of %TOC, %Carbonate and
124
estimated %detrital, which can exert a primary control on metal concentrations via
dilution (in the case of carbonate) or by drawdown (for detrital material). In our case
dominant changes in concentrations were distinct from these parameters. Only at the top
of the section does %detrital and the amount of carbonate seem to influence the trace
metal accumulation rates (see especially Pbppm and Pb%CFB as well as Cu).
Trace metals do not exhibit any relationship with estimated MAR
detrital
during the
Rhaetian, suggesting that the increase in trace metal concentrations of redox-sensitve
metals (e.g., V, U) seen during the Rhaetian is not driven by an increase in detrital
content. Lead, Mn, Co, Cu are flat during the Rhaetian, which suggests their background
delivery to the sediments did not majorly change, suggesting little change in nutrient,
organic matter delivery, and detrital input. In comparison, several trace metal correlation
coefficient values (Table 1) do suggest some correlation with MAR
detrital
during the
Hettangian portion of the section.

125
Triassic
Rhaetian ETE Hettangian
Jurassic
200.5 201 201.5 202 202.5 203 203.5 204
500
1000
1500
Zn (ppm)
200.5 201 201.5 202 202.5 203 203.5 204
0
Cd (ppm)
200.5 201 201.5 202 202.5 203 203.5 204
0
100
200
Cr (ppm)
200.5 201 201.5 202 202.5 203 203.5 204
0
5
10
Co (ppm)
200.5 201 201.5 202 202.5 203 203.5 204
0
Cu (ppm)
200.5 201 201.5 202 202.5 203 203.5 204
0
100
200
Ni (ppm)
200.5 201 201.5 202 202.5 203 203.5 204
0
Pb (ppm)
201 202 203 204
0
500
1000
Mn (ppm)
Figure S1. Zn, Cd, Cr, Co, Cu, Ni, Pb, and Mn report-
ed against time.
20
30
60
90
40
20
40
60
126
0 5 10
0
10
20
30
40
50
60
70
80
90
100
-30 -29 -28 -4 -2 0 2 0 8 16 0 500 0 50 0 15 30 0 4
Figure S2. δ
15
, δ
13
C
org
, δ
13
C
carb
, U, V , Mo, C:N, %TOC reported with stratigraphic height. Stratigraphic column
from Yager et al. (2017).
2
Mo (ppm)
δ
15
N‰
δ
13
C
org
‰ δ
13
C
carb
‰ U (ppm) V (ppm) C:N %TOC
127
0
10
20
30
40
50
60
70
80
90
100
0 1000
Zn (ppm)
0 50
Cd (ppm)
0 100 200
Cr (ppm)
0 10
Co(ppm)
0 40 80
Cu (ppm)
0 100 200
Ni(ppm)
0 40
Pb(ppm)
0 500 1000
Mn(ppm)
Figure S3. Zn, Cd, Cr, Co, Cu, Ni, Pb, and Mn reported with stratigraphic height. Stratigraphic column from
Yager et al. (2017).
20
128
Stratigraphic height
0 2 4 6 8 10 0 2 4 6 8 10 0 2 4 6 8 10 0 2 4 6 8 10 0 2 4 6 8 10 0 2 4 6 8 10
Triassic Jurassic
Panthalassa
A B C D F E
Tethys
δ
15
N
org
δ
15
N
org
δ
15
N
org
δ
15
N
bulk
δ
15
N
bulk
δ
15
N
bulk
Figure S4. Triassic-Jurassic Boundary nitrogen isotope records, plotted against stratigraphy and correlated
using C isotope stratigraphy and biostratigraphy. A: Kennecott Point, Haida Gwaii, Canada, Schopefer et al.,
2016; B: New York Canyon, Nevada, Ferguson Hill Section, this study; C: Levanto, Peru, this study; D: Marine-
tal-1 Core, Germany, Richoz et al., 2012; E: Mingolsheim Core, Germany, Quan et al., 2008; F: Doniford Bay,
UK, Paris et al., 2010
30 m
20 m
20 m
20 m
10 m
25 m
129
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132
Chapter 4. Depositional environment controls the
expression of Mercury concentration and isotope anomalies
associated with Large Igneous Province Magmatism and
the end-Triassic extinction

OPENING STATEMENT
In Chapter 1, I discussed the importance of linking CAMP magmatism to the
record of extinction (the marine sedimentary record). Mercury (Hg) concentrations and
isotopes in the marine sedimentary record are used here as a proxy for LIP activity.
Building on the work of Thibodeau et al. (2016), we present Triassic-Jurassic boundary
measurments of Hg concentration and isotopes from the New York Canyon, Nevada
Ferguson Hill section (extending the record from Thibodeau et al. 2016), St. Audrie’s
Bay (UK) and Levanto, Peru. These are three disparate depositional settings and provide
an opportunity to better understand the role depositional environment and diagenesis play
in recording Hg anomalies.
This is a large, collaborative project. Yadi Ibarra and I collected the St. Audrie’s
Bay samples, Renée Wang and I collected the New York Canyon samples, and the
Levanto samples are the same as those used in Chapters 2 and 3 (collected by Josh West,
Silvia Rosas, and I).
Hg concentration measurements took place in Bridget Bergquist’s lab at the
University of Toronto and in Aly Thibodeau’s lab at Dickinson College. I made
133
approximately 1/3 of the Hg concentration measurements and Aly Thibodeau, Laura
Zimmerman, and several other undergraduate REU students measured the remaining Hg
concentration measurements. Hg isotope measurements were all run in Bridget’s lab at
the University of Toronto by Aly Thibodeau and other people in Bridget’s lab.
%TOC and %CARB measurements were made in the Berelson lab at the
University of Southern California on his Picarro system. The Levanto %TOC and
%CARB is from Chapter 2, which I ran with help from Nick Rollins. I ran some of the
St. Audrie’s Bay samples for %TOC and Peter Wynn ran most of the New York Canyon
upper samples and remainder of St. Audrie’s Bay for %TOC and %TIC. %TIC and
%TOC measurements also involved two Young Researcher’s Program students, Melissa
Zepeda and Reyna Ibarra. All these data were quality controlled by Nick Rollins.
I interpreted the data, wrote the paper and made the figures with input from Josh
West, Aly Thibodeau, Bridget Bergquist, Frank Corsetti, Will Berelson, Peter Wynn,
Yadi Ibarra, Silvia Rosas, Sarah Greene, and David Bottjer. This paper is in preparation
for publication.

ABSTRACT
Mercury concentrations and isotopes have recently been used as a proxy for large
igneous province (LIP) volcanism in the sedimentary record. The close temporal
association of mass extinctions and LIP volcanism has led to a rapid expansion in the use
of Hg as a proxy for volcanism in the sedimentary record. Yet, questions arise based on
differences seen in Hg concentrations from different depositional environments, and
different depositional environments can also have different influences on Hg isotopes. In
134
order to better understand the Hg proxy, here we use Hg records from three sections
spanning the emplacement of the Central Atlantic Magmatic Province (CAMP) and end-
Triassic extinction (ETE) to investigate the role of depositional environment on the Hg
record. We find that at each section, depositional environment plays a role in both Hg
and Hg/TOC concentrations, which may hamper the use of the Hg proxy as a legitimate
fingerprint of CAMP. However, at each section an increase in Hg/TOC is observed at the
same relative time during the ETE and CAMP magmatism, suggesting that this ratio may
have some utility. Additionally, Mass Independent Fractionation (MIF) signatures of Hg
isotopes seem to support a volcanic origin of Hg during CAMP volcanism, whereas mass
dependent fractionation is found prior to and following CAMP. This suggests that Hg
isotopes may offer a way to distinguish between Hg loading from LIP magmatism on a
global scale.

4.1. INTRODUCTION
The prevalence of mass extinctions coincident with Large Igneous Province (LIP)
volcanism and the similarities between these intervals and modern anthropogenic CO
2

emissions necessitates a thorough understanding of the cascade of effects resulting from
LIP magmatism and their similarities and differences with modern climate change. The
extinction causes are largely regarded as due to a cascade of effects from the release of
volcanic gases (e.g. S, CO
2
) in high quantities over geologically rapid periods of time,
which perturb the Earth System and may lead to a range of outcomes like ocean
acidification, ocean anoxia, and warming (or cooling) detrimental to metazoan life (e.g.
Bond and Wignall, 2014). One challenge in understanding these mass extinctions and
135
their relationship to large igneous province magmatism has been the indirect temporal
and spatial association between the LIP and the main record of extinction, marine
sedimentary sections. Mercury (Hg) concentrations and isotope measurements from
sedimentary rocks have emerged as a potentially powerful tool for linking LIP
magmatism with changes observed in the marine sedimentary record and understanding
the of causes that lead to biosphere perturbation and mass extinctions.
Volcanic emissions are the primary natural source of Hg to the atmosphere, and up to
75% of natural Hg is released via volcanism (Pyle and Mather, 2003). In the atmosphere,
Hg has a ~1 year residence time, which enables a global distribution and deposition
(Schroeder and Munthe 1998; Douglas et al., 2008; Lindberg et al., 2002). Today, Hg has
an oceanic residence time of ~350 years, so local effects in marine sediments can be
major (Gill and Fitzgerald, 1988). Large, explosive eruptions can overwhelm the global
atmospheric Hg load. For significant increases in Hg above background in deep time
stratigraphic sections, volcanic emission is a likely source of Hg. Since Hg is thought to,
primarily, enter the sedimentary record complexed with organic compounds, comparing
Hg concentrations to %TOC is important to ensure an increase in Hg is not simply an
increase in Hg drawdown locally or due to the absence of dilution (e.g. Grasby et al.,
2013). An increase in Hg and Hg/TOC in multiple stratigraphic sections may suggest the
global impact of increased magmatism. However, volcanic style and depositional setting
and diagenetic history may also impact the Hg and Hg/TOC loading within the marine
sedimentary record (e.g. Percival et al., 2018) and the source of Hg as potentially also
derived from fires on land (Grasby et al., 2017) and general inconsistencies between
136
records of similar time periods (e.g. Percival et al., 2017) raise questions about the Hg
proxy and how useful it is as a fingerprint of LIP magmatism.
Hg isotopes can also be used to aid in fingerprinting the source of an Hg signal and
may further elucidate Hg source and therefore if the Hg originated with LIP magmatism.
Hg has seven stable isotopes and undergoes mass dependent fractionation (MDF) and
mass independent fractionation (MIF). MDF for Hg isotopes is typically reported using
202
Hg/
198
Hg ratio, reported as δ
202
Hg. MIF is measured as the difference between a
measured δ-value and that predicted on the basis of the measured δ
202
Hg value and the
kinetic MDF law, and is often reported as Δ
199
Hg (Blum and Bergquist, 2007; Blum et
al., 2014). Gaseous volcanic Hg enters the atmosphere with no MIF or MDF signal.
Continental cycling of Hg likely imparts a negative MIF signal during uptake by
biomasee and soils (Thibodeau and Bergquist, 2017) while distal settings may receive a
seawater derived Hg MIF signal of near zero or slightly positive (e.g. Thibodeau and
Bergquist, 2017; Grasby et al., 2017). Thibodeau et al. (2016) measured Hg isotopes in
the sedimentary record during LIP magmatism and speculated that the absence of MIF in
a shallow marine section was due to increased loading of Hg in the marine realm of
volcanism, and that a zero-MIF signature may be a proxy for LIP-derived Hg sourcing. In
Figure 2, we make a simplified Hg cycle diagram emphasizing the role contintal,
atmospheric and marine Hg deposition and isotope cycling may impart on different
depositional settings, with stylized depositional settings for the sections here (discussed
in sections 4.2; 4.4-5).
During the end-Triassic extinction, the Central Atlantic magmatic province
(CAMP; Marzoli et al., 1999) was emplaced over approximately one million years (e.g.
137
Davies et al., 2017) and in association with the end-Triassic extinction (ETE; 201.56 Ma;
Wotzlaw et al., 2014). The record of the ETE is largely preserved in the marine realm,
and often most of the LIP has been weathered. A record of CAMP in the marine
sedimentary record is therefore ideal for linking CAMP volcanism with the marine record
of extinction. During the end-Triassic, Hg and Hg isotopes were used to identify the
CAMP in one locality, and Hg was used to fingerprint CAMP in several other marine and
terrestrial sections (Percival et al., 2017). However, existing Hg and Hg/TOC ratios are
different at each section and are difficult to link directly to C cycle changes and age-dated
CAMP magmatism to fully understand the relationship between CAMP and Hg in the
marine sedimentary record. Here, we report Hg concentrations and isotopes from three
localities spanning the Triassic-Jurassic boundary in an effort to explore the similarities
and differences in Hg concentrations and isotopes from site to site that arise due to
depositional setting. In particular, we investigated one site that is depositionally similar
through the measured interval and is temporally constrained, which offers the opportunity
to directly compare the signal of Hg concentrations and isotopes in the sedimentary
record to the U-Pb ages for CAMP basalts.

138
4.2. OVERVIEW OF LOCALITIES
We measured three sections spanning the Triassic-Jurassic boundary from
disparate paleogeographic locations and different depositional settings (Fig 1) and
represent these as relative different depths in Fig 2 with relevant Hg cycle information.
Each locality is well studied and represents an important marine sedimentary section
spanning the Triassic-Jurassic boundary with ample prior work.

4.2.1. New York Canyon, Nevada
The New York Canyon area (specifically Ferguson Hill section) of Nevada is
comprised of laminated siltstones and shales and shaley marls. It represents the best-
studied Panthalassic section from the Triassic-Jurassic boundary and is the auxiliary
GSSP for the boundary. Several studies on the organic C isotope signature at the
Ferguson Hill section (Guex et al. 2004; Ward et al. 2007; Bartolini et al. 2012)
document the negative excursion in organic C isotopes. The Ferguson Hill section begins
in the Late Rhaetian with the Gabbs Formation and transitions into the Sunrise Formation
during the Hettangian (Fig 3). The Triassic-Jurassic boundary occurs within the Muller
Canyon Member of the Gabbs Formation, a ~17m thick shale interval that overlies a
robust carbonate ramp (e.g. Taylor et al. 1983; Schoene et al. 2010; Guex et al. 2004).
Above this shaley interval, the Ferguson Hill Member of the Sunrise Formation is
comprised of massive carbonates and cherts (Taylor et al. 1983; Ritterbush et al. 2014).
Overall, we interpret much of the studied section as shallowing upward, but also note the
impact of the low carbonate interval during the Muller Canyon Member, which may be
due to global drop in carbonate saturation (e.g. Greene et al. 2012) or to a loss of
139
New York Canyon
St. Audrie’s Bay
Levanto
volcanic Hg
0

199
Hg = 0‰
atmospheric Hg²
+
or Hg
0
photochemical reduction

199
Hg = >0‰
terrestrial runoff
biomass, soils Hg
0

199
Hg = <0‰
Figure 2. Relative depositonal settings of study sites and expected Hg, TOC and Hg isotope data at each site based on
relative depth and energy of environment. Although obviously not from the same paleogeographic areas, this represents a
simplified way of how Hg enters the marine record with particular attention to Hg isotopes and their relative contributions
based on proximity to the continent. Based on Thibodeau and Bergquist (2016) and references therein.
atmospheric influence terrestrial influence
199
Hg‰
199
Hg‰
MIF
140
carbonate producers (e.g. Kiessling et al., 2007, Ritterbush et al. 2014). The New York
Canyon area represents deposition within the mid, outer, and inner shelf (Ritterbush et al.
2014).

4.2.2. St. Audrie’s Bay, UK
The St. Audrie’s Bay section has been well studied for over 100 years
(Richardson 1905; 1906; 1911). Dramatic changes in depth, %TOC and %CARB make
this section ideal for assessing differences within one stratigraphic section of changes in
Hg and Hg isotopes. We place the Triassic-Jurassic boundary at ~meter 15 based on
organic C isotope correlation (and similar to George et al. 1969 and Hallam 1990, 1995)
but note that since P. spelae is absent the boundary is also difficult to pin down precisely.
Hesselbo et al (2004) provide an excellent assessment of the depositional changes seen at
the section, which we briefly summarize here. We followed the stratigraphy from
Hesselbo et al. (2004) for our sampling and use their stratigraphic column in Fig 4. The
lowermost ~2m are comprised of the Williton member of the Blue Anchor Formation,
which consists primarily of mudstone, has marine trace fossils and bivalves, and is
interpreted as shallow marine (Hesselbo et al. 2004; Mayall 1981). Meters ~2-12 are
comprised of the Westbury Formation, which consists of mudstone and siltstone with
carbonate concretions and phophatic conglomerate (Richardson 1906, 1911; Hesselbo et
al 2004). The Westbury is characterized by relatively low %TOC (although note scale
difference between Fig. 3 and 4) and carbonate is typically in diagenetic, concretionary
horizons. The Westbury is generally interpreted as deeper and further offshore compared
to the Williton member, but the uppermost Westbury represents a shallowing (Hesselbo
141
et al. 2004). The Cotham Member of the Lilstock Formation is comprised of mudstones
and limestones and is interpreted as a shoreface equivalent to the Westbury Formation
(Hesselbo et al. 2004). The Cotham member contains an erosional surface and dessication
cracks and ooids, representing a substantial shallowing relative to the rest of the section,
subaerial exposure, and potentially non- marine conditions (Hesselbo et al 2004 and
references therein). This is where the negative organic C CIE occurs and may represent
the ETE based on C isotope correlation. The Langport Member of the Lilstock
Formation is comprised of limestone and mudstone and is interpreted as fully marine but
relatively shallow based on wave ripples (Richardson 1911; Hallam 1960; Swift 1995).
The Blue Lias Formation is comprised of organic-rich shale and limestones that are likely
a product of diagenetic mobilization of carbonate (e.g. Hallam 1964). Burrowing
intensity varies substantially, and carbonate-rich beds typically reflect less organic-rich,
oxygenated settings while the more organic rich facies are interpreted to reflect anoxic
sediment water interface (Hesselbo et al. 2004). Fossils and pyrite are common and
suggest marine but potentially euxinic water column or sediment column conditions
(Wignall 2001; Hesselbo et al. 2004). In general, the shallowest portion of the section is
during the ETE, while the remainder of the exposed Rhaetian and Hettangian are
relatively deeper but with very different %TOC and %CARB, likely due to differences at
the sediment water interface and during early diagenesis.

4.2.3. Levanto, Peru
The Levanto section in Northern Peru spans the Late Triassic and Early Jurassic,
and is continuous for about 4 million years. The entirety of the outcrop is present as part
142
of the Aramachay formation which here is comprised of carbonate-rich mudstones with
intercalated ash beds (Fig 5). U-Pb absolute age dating of zircons in these ash beds and
ammonite biostratigraphy (Schaltegger et al., 2008; Schoene et al., 2010; Guex et al.,
2012; Wotzlaw et al., 2014) provide the durations of the Rhaetian and Hettangian as well
as a biostratigrahic and temporal framework to geochemical work at the section. The
section is well below storm wave base and is characterized by little bioturbation and thus
interpreted as anoxic at the sediment water interface during deposition. Prior work on
carbon isotopes, %TOC and %CARB (Yager et al. 2017) record a typical Triassic-
Jurassic boundary carbon isotope profile. Unlike many Tethyan sections, Levanto is
characterized by decreased %TOC during the Hettangian relative to the Rhaetian.
%CARB remains relatively high (~60%) through much of the section but is noisy,
particularly at the top of the section, where carbonate is concentrated in thick bedded
intervals.
For the first ~57 meters of continuous section, approximately 1/3 meter packages
of alternating thin and thick-bedded intervals persist, with little influence to thin sections
(Yager et al. 2017). At approximately 57m, this alternation changes to meter-scale
differences, and eventually (circa meter 80) grades into concretionary bedding and finally
into meter-scale concretions (approximately meter 85). Thin sections are characterized by
carbonate-replaced radiolarians, rare foraminifera and sponge spicules, and low coarse
detrital content (<5%). In summary, the Levanto section records a relatively static
depositional environment spanning approximately four million years and within robust
geochronological constraints. Although nearly every Triassic-Jurassic Boundary section
143
records a facies change to carbonate-poor strata (Ritterbush et al. 2014), the Levanto
section does not.

4.3. MATERIALS AND METHODS
4.3.1. Sample processing
Samples were collected from outcrop, cut to remove weathered material, veins,
and marine derived debris (St. Audrie’s Bay). Samples were crushed in a jaw crusher and
pulverized either in a disk crusher (New York Canyon samples) at USC or in a bill mill at
USC (St. Audrie’s Bay samples) or at Actlabs (Levanto samples).

4.3.2. Hg concentrations
Hg concentrations were measured following the methods from Thibodeau et al.
(2016). Briefly, total Hg was measured using a Hydra IIc at Toronto. Powdered samples
are combusted under O
2
flow at 350 ml/min, heated in a drying step to 300ºC for 40s,
then decomposed for 300s at 800ºC. Following combustion, evolved gases were carried
through a heated (600ºC) catalyst tube for 60 s to remove possible interferences (e.g.
halogen compounds, sulfur oxides, nitrous oxides) and Hg was captured on a gold trap
while combustion gases were removed from the detection cell. The gold trap was heated
for 30s at 600ºC to release Hg, which was then carried to the detection cell where
absorbance from a mercury lamp was measured at 253.7 nm. Calibration was made using
NIST 3133 Hg standard in a 0.25% L-cysteine solution. Blank absorbance was <2% of
typical sample signals and always <4%. NIST 3133 was periodically combusted and
analyzed alongside samples to determine precision, and were within 5% of the nominal
144
values. Samples measured more than once are reported as averages, which typically have
reproducibility better than 10%. NIST SRM 1944 and 1646a were combusted alongside
samples to check measurement accuracy. Errors on Hg concentration measurements are
estimated to be 10% (2sd) based on reproducibility of samples and external standards.

4.3.3. Hg isotope measurements
Hg isotope measurements followed the analytical approach from Thibodeau et al.
(2016). Briefly, Hg was extracted and purified from samples using the Hydra IIc without
the gold trap (same decomposition as described for Hg concentration measurements). Hg
was trapped by directly sparging the gas outflow with elemental Hg into ~10% H
2
SO
4

(v/v) and ~1% KMnO
4
(w/w), which oxidized the Hg
0
gas to Hg(II). To ensure removal
of residual Hg in the furnace, after each sample combustion 50 uL of Milli-Q was
combusted and the Hg was recovered. NIST 3133, and 1646a were combusted and
trapped as procedural standards and blanks.
Procedural blanks were <0.02 ng/g, which is <1-2% of the sample Hg. Hg
recovery was checked by neutralizing an aliquot of each solution with NH
2
OH-HCl
immediately after vapor trapping and measuring its concentration using a Tekran 2600
cold vapour atomic fluorescence spectrometer. The ~10% variation in sample recoveries
reflects the uncertainty in concentration method and sample heterogeneity. Hg isotope
analyses were conducted with a cold vapor multi-collector inductively coupled mass
spectrometer (Neptune Plus, Thermo-Finnigan) at the University of Toronto. Sample
solutions were neutralized with NH
2
OH-HCl (which reduces them to KMnO
4
) and
diluted to 1-2ng/g with a KMnO
4
solution. Hg was introduced to the plasma as Hg
0
with
145
a SnCl
2
reduction and Hg
0
vapor separation. Internal standards (standard-sample
bracketing with NIST 3133 was used to correct for instrumental mass bias and an in
house Hg standard (J.T. Baker Chemicals) was measured multiple times in each
analytical session to determine external reproducibility. Signal concentrations and
intensities of all standards and samples were matched within 10%. Isobaric interference
from
204
Pb was monitored using
206
Pb, but was always negligible (correction never
altered the calculated δ
204
Hg). On-peak blank corrections were made on all Hg and Pb
masses and the Hg intensities of the blank measurements were monitored to ensure
negligible carry-over and build up of Hg.
All samples and procedural standards were measured at least twice and sample
isotope values are reported as the mean of duplicate or triplicate measurements
(Appendix I). Average values for procedural standards are reported in Appendix I, and
are consistent with previous values for these standards (Thibodeau et al. 2016). Sample
errors are reported as either the 2 s.e.m. of sample replicates or the 2 s.d. of the in-house
JT Baker Hg standard, whichever is larger.

4.3.4. %TOC and %TIC
%TOC Weight percent organic carbon (%TOC) was determined on the residual
decarbonated powder using a Picarro cavity ring down spectrometer (CRDS) (G2131-i)
coupled via a Picarro Liaison (A0301) to a Costech Elemental Combustion System (EA
4010). Picarro measurements of CO
2
concentration were calibrated to determine %C in
samples using the USGS-40 standard (L-glutamic acid) weighed at 5 different samples
masses and run at the beginning and end of each set of ~15 samples. Determination of
146
%TOC took into account the amount of carbonate lost during decarbonation. Errors were
calculated by replicate analysis of samples and standards (typically ~2 replicates per
sample; see Supplementary Table 1). Standard deviation of replicates for measured
%TOC was ±0.08 on average, or ~ ±3% of the measured value (1s, standard deviation).
Because of potential errors introduced by small amounts of sample loss during liquid
decarbonation, including via solubilization of organics (Galy et al., 2007), we take a
conservative estimate of ±10% uncertainty on the measured value for reported %TOC.
%TIC Depending on the sample’s %TIC, 3-200 mg of sample was weighed into
10mL glass Exetainer vials with rubber septa caps. Vials were evacuated and acidified
with 1 mL 30% H
3
PO
4
. Samples and standards were heated for 80 minutes in a water
bath at 70°C to ensure that C associated with all carbonate phases was released as CO
2
.
Samples were then run on a Picarro CRDS coupled to an Automate prep device, which
sparges the solution with N
2
gas to drive CO
2
into the analyzer. In-house carbonate
standards Optical calcite (OPT) and AR15 were run at different masses to calibrate
%TIC. Errors were calculated by replicate analyses of samples and standards. Average
error (1s) for %TIC measurements was ±0.04, or <1% of the measured value. Weight
percent carbonate (%CARB) was calculated from measured %TIC, assuming all
inorganic carbon is CaCO
3
as opposed to dolomite, given the absence of dolomite or
other carbonate phases observed in thin sections of these samples.

4.4. RESULTS
We report Hg, %TOC and Hg isotopes in the supplemental data set (Appendix I) .
We analyzed 193 samples for Hg concentrations and 18 samples for Hg isotopes from the
147
Levanto section, 80 samples for Hg concentrations and 13 for Hg isotopes from St.
Audrie’s Bay, and 81 samples from New York Canyon (which are stratigraphically above
those reported by Thibodeau et al., 2016), thus complementing the previously published
35 concentration and 35 isotope measurements from this section.
In Figures 3-5, we report Hg, %TOC, Hg/TOC, δ
202
Hg, and Δ
199
Hg for each
section with stratigraphy. We note in each section what is ‘pre extinction’ or Rhaetian
until the onset of the ETE or negative C isotope excursion, during the ETE or from the
onset of the negative CIE to the TJB, and post extinction or Hettangian in age for ease of
comparison (however note that the ETE is technically during the Rhaetian). We also plot
cross plots of %CARB, Hg, Hg/TOC and %TOC in Fig 6 for each section.

4.4.1. New York Canyon
In Figure 3 and Fig 6a-c we report data from Thibodeau et al. (2016) and
additional data from this study. Pre-extinction Hg concentrations have an average value
of ~12 ± 4 ppb (n=4; 1sd), rise to ~50 ± 21 ppb (n=14, 1sd) during the ETE and decrease
to ~11 ± 10 ppb (n= 100). Hg/TOC is ~48 ppb/wt% during the pre-extinction, rises to
~243 ppb during the ETE, and decreases to ~100 ppb/wt% during the post extinction
interval. Hg isotopes (reported and discussed in Thibodeau et al. 2016) record δ
202
Hg
during the Rhaetian and early Hettangian between ~0 and -1.5, with a trend towards more
negative values upsection. Δ
199
Hg is near zero during the ETE and early Hettangian, and
displays some MIF during the later Hettangian. Hg is correlated with %TOC in particular
during the Hettagnian (Fig 6c).

148
-5
0
5
10
15
20
25
30
35
40
0 20 40 60 80 100 0.1 0.2 0.3 0.4 0.5 0.0 0 200 400 600 -2.0 -1.5 -0.5 0.5 0 -1.0 0.2 0.0 -0.2 -0.4
New York Canyon, Nevada
Hg/TOC (ppb/wt%) %TOC Hg (ppb)
δ
202
Hg‰ 199
Hg‰
pre ETE post
Gabbs Sunrise
Triassic Jurassic
Figure 3. tratigraphic column from e ork Canyon, eada (Corsetti et al. 201) ith g, C gC δ
202
g and 199
Hg from this study and Thibodeau et al. (2016).
149
4.4.2. St. Audrie’s Bay
Hg concentrations during the Rhaetian at St. Audrie’s Bay are on average ~30
ppb, during the ETE are on average ~20 ppb, and during the Hettangian are ~42 ppb.
Hg/TOC during the Rhaetian is on average ~50 ppb, rises to ~150 ppb coincident with
the onset of the negative C isotope excursion (meter ~12), and decreases to ~20 ppb
during the Hettangian. Hg concentrations correlate with %TOC, especially during the
ETE (r
2
=0.51) and Hettangian (r
2
=0.90; Fig 6c).
δ
202
Hg in the St. Audrie’s Bay rocks is between ~-1.50‰ and -0.50‰ for the
measured section; Δ
199
Hg is negative during the Rhaetian (-0.20‰ to -0.40‰), near zero
during the ETE (-0.10‰) and negative again during the Hettangian (-0.20‰ to -0.40‰).

4.4.3. Levanto
Hg concentrations from the Levanto section are on average ~33 ppb during most
of the Rhaetian (pre-extinction), ~37 ppb during the ETE and ~36 ppb during the
Hettangian (Fig 5). Hg/TOC at Levanto is on average~24 ppb/%TOC during the
Rhaetian, rises slightly to ~30 ppb/%TOC during the ETE, and rises to ~64 ppb/%TOC
during the Hettangian. The onset of increased Hg/TOC happens at approximately 57
meters, coincident with the termination of the negative CIE in organic carbon isotopes.
Hg and Hg/TOC are negatively correlated with %CARB (Fig 6g-h) during the ETE and
Hettangian. δ
202
Hg is between ~-1.30‰ and -0.30‰ for the measured section, with a
possible excursion from -0.3‰ to -1.5‰ during the late Rhaetian and ETE; D
199
Hg is
slightly positive during the Rhaetian (~0.1‰) and near zero without discernable MIF
during the ETE and Hettangian (±0.05‰).
150
0
5
10
15
20
25
Rhaetian
Westbury Lils. Will. Blue Lias
Hettangian
Triassic Jurassic
0 100 200 -2.0 -1.5 -0.5 0.5 0 -1.0 -0.6 0.2 0.0 -0.2 -0.4 0 0 4 8 12 40 80 120
St. Audrie’s Bay, UK
Hg/TOC (ppb/wt%) %TOC Hg (ppb)
δ
202
Hg‰ 199
Hg‰
pre ETE post
Figure 4. tratigraphic column from t. Audries Bay, K (esselbo et al. 2004) ith g, C gC δ
202
g and 199
Hg from
this study.
151
0
20
40
60
80
100
0 40 80 -2.0 -1.5 -0.5 0.5 0 -1.0 -0.6 0.2 0.0 -0.2 -0.4 120 0 0 1 2 3 4 5 40 80 120 160
Hg/TOC (ppb/wt%) %TOC Hg (ppb)
Levanto, Peru
δ
202
Hg‰ 199
Hg‰
pre ETE post
Rhaetian
Aramachay
Hettangian
Triassic Jurassic
Figure 5. tratigraphic column from eanto, Peru (ager et al. 201) ith g, C gC δ
202
g and 199
Hg from this study.
152
A B C
D
E
F
New York Canyon, Nevada
St. Audrie’s Bay, UK
Figure 6. Crossplots
0 40 80
0 40 80
0
200
400
600
Hg/TOC
0.2 0.4 0.6 0.0
%TOC
Hg (ppb)
0
40
80
120
Hg (ppb)
0
40
80
120
%CARB %CARB
r²= 0.30
r²= 0.08
pre-ETE
post-ETE
ETE
pre-ETE
post-ETE
ETE
pre-ETE
post-ETE
ETE
r²= 0.02
r²= 0.28
r²= 0.50
r²= 0.08
Hg/TOC
%TOC
Hg (ppb)
Hg (ppb)
0
40
80
120
0
40
80
120
0 5 10 15
0
100
200
300
0 40 80
%CARB
0 40 80
%CARB
r²= 0.11
r²= 0.01
r²= 0.01
pre-ETE
post-ETE
ETE
r²= 0.67
r²= 0.90
r²= 0.64
pre-ETE
post-ETE
ETE
r²= 0.91
r²= 0.51
r²= 0.18
pre-ETE
post-ETE
ETE
153
G
H
I
I
Levanto, Peru
Figure 6. Crossplots continued.
0
0
20
20
40
40
60
60
80
80
100
100
%CARB
%CARB
0
50
100
Hg (ppb)
Hg/TOC
120
0
20
40
60
80
100
Hg (ppb)
120
0 20 40 60 80 100
150
02 4
%TOC
pre-ETE
post-ETE
r
2
= 0.12
r
2
= 0.66
r
2
= 0.76
ETE
r²= 0.56
r²= 0.04
r²= 0.47
pre-ETE
post-ETE
ETE
r²= 0.00
r²= 0.08
r²= 0.05
pre-ETE
post-ETE
ETE
154
In the Rhaetian portion of the Levanto section, no discernible lithologic control
between high Hg samples and low Hg samples is distinguishable from outcrop or thin
section observations. However, during the Hettangian (Fig 7), the alternations in thick
and thin bedded strata appear to control Hg and Hg/TOC: samples high in Hg are
compacted and contain less carbonate and slightly higher %TOC, while samples that are
uncompacted and high in %CARB contain less Hg and lower Hg/TOC. The transition
seen at ~57 meters coincides with an increase in the variability of %CARB, with samples
with lower %CARB preserving higher Hg concentrations (Figure 8).

4.4.4. Consistencies between sections
Using organic C isotopes as a correlation tool (Figure 9), at all three sections
Hg/TOC rises during the negative isotope excursion and ETE. At New York Canyon and
St. Audrie’s Bay, Hg/TOC decreases in the Early Jurassic, while at Levanto Hg/TOC
remains elevated. Each section also exhibits no or low MIF (near zero Δ
199
Hg) during the
ETE. New York Canyon and Levanto may both record a slightly negative shift in δ
202
Hg
during the Late Rhaetian and ETE, although low sampling resolution in Hg isotopes from
Levanto and St. Audrie’s Bay may obscure these results.

4.5. DISCUSSION
4.5.1 Lithologic controls on Hg/TOC
Levanto Hg is enriched in samples from thin beds with low %CARB and few
fossils preserved, and is lower in carbonate-rich, concretionary beds. %TOC is lightly
enriched in thin beds as well. Interestingly, this relationship is not as strong in the lower
155
80m
81m
82m
LV174
LV175
LV176
Levanto, Peru
Figure 7. Upper Levanto section Hg is enriched in compacted, thin beds and depleted in
carbonate-rich, concretionary beds preserving radiolarians; %TOC is also slightly enriched
in thin beds
LV174
Hg = 73.33 ppb
%TOC= 0.66
Hg/TOC= 111 ppb/wt%
%CARB=14%
Hg = 23.5 ppb
%TOC= 0.31
Hg/TOC= 75 ppb/wt%
%CARB=58%
LV175
Hg = 52.6 ppb
%TOC= 0.56
Hg/TOC= 93 ppb/wt%
%CARB=12%
LV176
156
Figure 8. Change in Hg/TOC ~57 meters at the Levanto section. Although lithology does
not dramatically change, %CARB and to some extent %TOC do, which likely dilutes Hg
and Hg/TOC.
55m
56m
57m
LV121, 56.5 M
LV120, 56.0 M
change at 57.1m -- first lower %CARB, high Hg/TOC sample
58m
LV119
Hg = 13.6 ppb
%TOC= 1.23
Hg/TOC= 11 ppb/wt%
%CARB=70%
LV121
Hg = 14.8 ppb
%TOC= 2.5
Hg/TOC= 6 ppb/wt%
%CARB=76%
LV122
Hg = 61.8 ppb
%TOC= 0.9
Hg/TOC= 73 ppb/wt%
%CARB=42%
157
Figure 9. Hg and Hg/TOC data and Hg isotope data plotted against stratigraphy for each
site and related based on organic C isotope correlation. Stratigraphic column for New York
Canyon is from Thibodeau et al. (2016); stratigraphic column from St. Audrie’s Bay is
from Hesselbo et al. (2004); stratigraphic column from Levanto is from Yager et al.
(2017). Data from the lower portion of the New York Canyon section is from Thibodeau
et al., 2016 .
0
5
10
15
20
25
Triassic Jurassic
0 100 200 -0.6 0.2 0.0 -0.2 -0.4
Hg/TOC (ppb/wt%) 199
Hg‰
pre ETE post
0
5
10
15
20
25
30
35
40
0 200 400 600 -0.6 0.2 0.0 -0.2 -0.4
Hg/TOC (ppb/wt%)
199
Hg‰
pre ETE post
Triassic Jurassic
0
20
40
60
80
100
-0.6 0.2 0.0 -0.2 -0.4 0 40 80 120
Hg/TOC (ppb/wt%) 199
Hg‰
pre ETE post
Triassic Jurassic
Levanto, Peru
New York Canyon, Nevada
St. Audrie’s Bay, UK
158
portion of the section, where a weak relationship is observed between %CARB and Hg
(Fig 6 g-i) and samples enriched in Hg (e.g. LV70, Hg = 90 ppb) are not distinct from
nearby samples lithologically (see Appendix A thin section photos). This suggests that
the depositional and/or diagenetic processes of Hg and carbonate preservation are slightly
different in the Rhaetian vs remainder of the section. Whether this reflects a change in the
oxygenation of bottom water, causing different early diagenetic reactions in the pore
water, is due to dilution of Hg concentrations in carbonate-rich beds, is due to Hg
diagenesis in carbonate-rich layers or perhaps Hg stays with the clay fraction; these
possible explanations require further work. Additionally, it also appears that Hg, in
contrast to other trace metals, is the most susceptible to this alteration pattern (Yager et
al. in prep).
This raises the additional question of what the potential effect of this migration of
Hg or carbonate during early diagenesis is on Hg isotopes. Although Levanto does not
have dramatic lithologic changes within the section, %CARB and %TOC seem to play a
substantial role in controlling Hg concentrations. Furthermore, the deeper and more distal
depositional environment of Levanto likely limits the amount of Hg in the system. The
lower %TOC during the Hettangian is unlikely to be from depositional change, but could
be from a change in early diagenesis and/or possible higher oxygenation and less
preservation. However, no change in sedimentary structures and lamination is observed
here, although phosphate nodules are found in the Rhaetian and not in the Hettangian.
Another possibility is that following the end-Triassic extinction productivity in the region
may have decreased, yielding less organic matter to preserve at the site. Hg/TOC remains
159
high for the entirety of the Rhaetian, which also raises a question as to whether this signal
is due to a change in source material or from continued CAMP activity.
Δ
199
Hg suggests a marine-derived signal, with little continentally derived Hg.
This may account for the relatively low Hg concentrations at Levanto (given the high
%TOC): Levanto is only getting atmospheric and oceanic Hg, and is not getting
continental runoff Hg (also see Percival et al. 2018). Yet counter to this interpretation,
δ
202
Hg appears influenced by some soil/continental cycling..

St. Audrie’s Bay In contrast to the Levanto section, Hg in St. Audrie’s Bay is
tightly correlated with %TOC (Fig 6F), especially during the post-extinction interval
(r
2
=0.90). This suggests that at the St. Audrie’s Bay section, the Hg/TOC ratio may
largely account for lithologic differences from bed to bed that dictate %TOC. However,
at the Hg/TOC peak, %CARB is at a maximum and %TOC is at a minimum, and error in
%TOC measurements may greatly affect the calculated Hg/TOC. The Hg/TOC peak is
also likely the shallowest depositionally from St. Audrie’s Bay, which may play a role in
the Hg/TOC peak. Yet, the Hg/TOC maxima is defined by 6-8 data points and clearly
occurs within the ETE interval and is thus consistent with the New York Canyon section.

4.5.2 Depositional setting and Hg isotopes
Hg isotopes largely reflect the depositional setting of each section. More
continental influence should impart more influence from biomass and soil and provide a
negative MIF, as seen in St. Audrie’s Bay (except during the extinction interval). MDF
should also become negative in continental settings, as seen in St. Audrie’s Bay. From
160
New York Canyon, no MIF during the ETE coincides with increasingly negative MDF,
which coincides with a shallowing upward section. This may suggest MDF records the
shallowing, and increase in continental-derived material, or loss of the biomass on the
continent from the mass extinction interval. From the Levanto section, slight positive
MIF supports a largely marine and atmospheric Hg source, while slight negative MDF
suggests some continental input. This may reflect some input from the continent.
Interestingly, a negative shift in MDF during the Late Rhaetian and ETE may point to an
increase in the continental influence. If so, this may suggest Hg isotopes are not only
useful in fingerprinting magmatism but also the continental vs marine inputs to a system.

4.5.3. Implications for applying Hg concentrations and isotopes as a proxy for
magmatism in the sedimentary record
From the Levanto section plotted against time (Fig 10), we can see that CAMP U-
Pb ages do not coincide with all the observed Hg peaks, which suggests either Hg and
Hg/TOC from the Levanto section are not primarily controlled by atmospheric Hg from
CAMP magmatism or that CAMP U-Pb ages are incomplete. And yet there is a marked
change in mean Hg/TOC that occurs across the ETE. It’s possible that intrusive
age (Ma)
Jurassic Triassic ETE
0
50
100
201 202 203 204
Hg/TOC (ppb/wt%)
CAMP U-Pb
Figure 10. Levanto section Hg/TOC data (this study) plotted using the age model from Yager et al.
(2017) and displayed with CAMP U-Pb age dates from Davies et al. (2017).
161
magmatism does not release Hg, and may account for the delayed peak in Hg/TOC at the
Levanto section relative to the CAMP U-Pb ages from Davies et al., (2017). However, it
seems unlikely that elevated Hg/TOC during all of the Hettangian is due to unknown
sources from CAMP. This means that at some sites, Hg/TOC will not fingerprint
magmatism, and casts doubt on the idea of fingerprinting pulses of magmatism directly
(e.g. Percival et al., 2017).
However, all three sections record no to low MIF during the ETE and a peak in
CAMP magmatism. This suggests that Hg isotopes may indeed provide an additional
constraint on the source of Hg and potentially confirm its volcanic origin.
Our findings corroborate those found by Percival et al. (2018), Grasby et al.
(2016) and outlined by Thibodeau and Bergquist (2016), and raise new questions. Grasby
et al. (2016) note the presence of pyrite framboids, interpreting them as indicative of
water column euxinia. It is also possible that S is scavenging mercury (e.g. Appendix F),
and that %TOC normalization does not adequately represent potential sources of Hg
drawdown. Additionally, although dilution of carbonate and/or scavenging by clay or
organic matter is not entirely suprising for mercury, what is surprising is that this is not
observed for other metals (e.g. Yager et al in prep). This raises the question of what is
controlling Hg deposition in sedimentary sections, and whether this is primarily due to
water column scavenging (e.g. by organic matter); early diagenetic pore fluid scavenging
(e.g. by sulfides) or dilution during carbonate dissolution and remobilization (e.g.
carbonate dilution). The sources, sinks and potential diagenetic effects of Hg are unique
amongst trace metals and caution is needed when interpreting Hg records in deep time.

162
4.6. CONCLUSIONS
Hg/TOC or Hg concentrations increase at all three of the measured sections
spanning the Triassic-Jurassic boundary in association with the ETE and CAMP
emplacement. At the Levanto section, Hg/TOC remains elevated longer than the
youngest U-Pb CAMP ages, suggesting some depositional or sediment source change
may be affecting Hg and Hg/TOC at this deeper water site. Hg isotopes resemble the
expected signatures based on each sites depositional environment: shallow, near shore
site’s have negative δ
202
Hg and Δ
199
Hg, and may even corroborate existing interpretations
of shallowing upwards at New York Canyon. Additionally, Hg isotopes may also reflect
the loss of biomass on the continent during the ETE and a subsequent change in Hg
cycling. In a deeper basinal setting, slightly positive MIF suggests majorly atmospheric
and marine-influenced Hg source, but δ
202
Hg suggests some continental influence to
MDF signatures. At each site, MIF is near zero during the ETE and CAMP magmatism,
suggesting Hg isotopes may have come from a volcanic source with minimal cycling at
that time.

163
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Muller Canyon, Nevada, USA, Palaeogeography, Palaeoclimatology, Palaeoecology,
v. 244, p. 281-289.
Wignall, P.B. 2001. Sedimentology of the Triassic – Jurassic boundary beds in Pinhay
Bay (Devon, SW England). Proceedings of the Geologists’ Associa- tion, 112, 349–
360.
Wotzlaw, J.F., Guex, J., Bartolini, A., Gallet, Y., Krystyn, L., McRoberts, C.A., Taylor,
D., Schoene, B., Schaltegger, U., 2014. Towards accurate numerical calibration of
the Late Triassic: High precision U-Pb geochronology constraints on the duration of
the Rhaetian. Geology 42, 571-574, doi: 10.1130/G35612.1.
169
Yager, J. A., West, A. J., Corsetti, F., Berelson, W. M., Rollins, N. E., Rosas, S, Bottjer,
D. J., 2017, Duration of and decoupling between carbon isotope excursions during
the end-Triassic mass extinction and Central Atlantic Magmatic Province
emplacement. Earth Planet. Sci. Lett. v. 473, p. 227-236; doi:
10.1016/j.epsl.2017.05.031.

170
Chapter 5. Silicon isotopes in sponge spicules suggest low
dissolved silica during the mid-Mesozoic and drawdown by
sponges in aftermath of end-Triassic extinction

OPENING STATEMENT
In Chapter 1, I discussed how the Mesozoic silica cycle is underconstrained in
terms of silica saturation in the ocean. I also discussed the presence of siliceous sponges
in shallow benthic environments during the Early Jurassic (Ritterbush et al. 2014; 2015)
and the hypothesis that CAMP-derived weathering delivered silicic acid to the oceans
that benthic sponges may have benefitted from.
Here, we obtain the first measurements of Mesozoic sponge spicule δ
30
Si, which
is a proxy for silicic acid concentrations in the ocean. Josh West designed the project.
Several years ago I prepped some of Kathleen Ritterbush’s central Peru samples for
SIMS, which we did not run because we felt we needed Triassic samples to compare to
the Jurassic samples. There are rare sponge spicules in the Levanto samples, and Peter
Wynn and I screened these for siliceous sponge spicules. Frank Corsetti had the
important idea of making bed parallel thin sections to maximize spicule surface area,
enabling us to make multiple measurements on single spicules. I sent these samples out
for preparation and we got four samples with multiple siliceous sponge spicules
preserved. I ran the first sample with Lizzy Trower and Yunbin Guan at Caltech, and then
ran the remainder of the Levanto samples and two of the central Peru samples with
Yunbin at Caltech. I obtained modern sponge material from the Los Angeles Natural
171
History Museum and a core from the Santa Monica Basin from the Berelson lab. I
cleaned these sponges and heat treated some of them in a furnace and then sent them to
be prepared for SIMS sectioning.
I worked up the data with advice from Josh West and Lizzy Trower, made the
figures, analyzed the data, interpreted the results and wrote the paper. Woody Fischer,
Josh West and Lizzy Trower all helped with the interpretations.
I ran some of the heated and unheated samples for Raman spectroscopy at the
Natural History Museum with Aaron Celestian in an attempt to distinguish between opal-
a and possibly opal-CT.

ABSTRACT
Silicon is a major nutrient in the ocean and is thus linked to the carbon cycle.
Little is known about dissolved Si concentrations (DSi) in the oceans in deep time, a
major gap in our understanding of the silica cycle in the past and how it has evolved. The
silicon isotope ratio of modern sponge spicules is related to the DSi in the waters in
which they grew, so isotope ratios in spicules from the past may offer a proxy for the DSi
of the ocean in deep time. Here, we report the first δ
30
Si measurements from Mesozoic
sponge spicules, from samples spanning ~4 Ma around the Triassic-Jurassic Boundary
(201.3±2 Ma). To analyze individual, rock-hosted spicules, we use secondary ion mass
spectrometry (SIMS), obiviating the necessity for bSi removal from the matrix. We also
measured modern sponge spicule δ
30
Si via SIMS to compare our samples to these well-
characterized spicules (since δ
30
Si on sponge spicules has typically been made by
dissolution and MC-ICP-MS). We find that spicule δ
30
Si during the Late Triassic and
172
Early Jurassic is similar to the range of δ
30
Si observed in modern sponge spicules,
suggesting that mid-Mesozoic silica concentrations were a similar order of magnitude to
those in the modern ocean. This interpretation contrasts the prevailing hypothesis that
dissolved silica was much higher prior to ~60 Ma and implies that radiolarians and
sponges were effective at drawing down silica prior to the major evolutionary radiation of
diatoms, which are the main consumers of dissolved silicon in the ocean today. Our data
also reveal a subtle shift towards heavier δ
30
Si in the aftermath of the end-Triassic
extinction, which may be consistent with sponge proliferation during the Early Jurassic,
further drawing down silicic acid in the ocean.

5.1. INTRODUCTION
The marine silica cycle is tightly coupled to the carbon cycle in the oceans and thus to
atmospheric carbon dioxide, making it a vital component in understanding climate
change (Pondaven et al., 2000; Berner and Caldeira, 1997). The silica cycle has been
evoked as a potential regulator for atmospheric CO
2
and climate during the Precambrian
via weathering feedback (Isson and Planavsky 2018). The Precambrian, pre-
biomineralization silica cycle was supersaturated in the oceans while the modern,
biomineralization driven silica cycle is undersaturated. The Phanerozoic silica cycle has
received little attention compared to the modern and Precambrian, despite its vital link
between the Precambrian and modern oceans and its role in the evolution of marine life
on the planet. Gaining an understanding of the silica cycle during the Phanerozoic is
important to our understanding of the interplay between the carbon and silica cycles in
deep time as well as the silica cycle’s role in the evolution of life on Earth.
173
In the modern ocean, silica (typically as silicic acid, Si(OH)
4
) is undersaturated with
respect to opal (or quartz), and is also an essential nutrient to some phytoplankton.
Precambrian outcrops are often bedded cherts, and in the absence of biomineralization,
the Precambrian silica cycle involved abiotic precipitation and supersaturated ocean
conditions (Siever 1992; Maliva et al 2005; Perry and Lefticariu 2003). In between the
Precambrian and modern, dissolved silica concentration (hereafter DSi) must have
declined, but the timing and its relation to the evolution of marine life remains unclear.
For much of the Phanerozoic (since 560 Ma), DSi is classically interpreted as having
been orders of magnitude higher than in the modern ocean based on the frequency of
chert occurrences in outcrops and radiolarites in the rock record (e.g., Siever, 1991, Racki
and Cordey, 2000). Diatoms, which are the primary sink for dissolved silica in the
modern ocean (Tréuger and De La Rocha, 2013), may have evolved around ~250 Ma and
became prolific during the Paleogene ca. 60 Ma, leading to the hypothesis that DSi might
have been elevated until they began to dominate the Si cycle (Maliva et al., 1989).
However, the first measurements of silicon isotopes on sponge spicules (a proxy for DSi)
from the Paleogene recorded low (similar to modern) DSi as far back as 60 Ma and found
no evidence for change during the Paleogeone (Fontorbe et al. 2016). If there was a
stepwise change in the DSi of the oceans, it occurred before the Paleogene, but the timing
remains entirely unknown.
During the end-Triassic extinction (ETE, 201.35 Ma; Wotzlaw et al., 2014),
which occurred just before the Triassic-Jurassic Boundary (TJB; 201.56 Ma; Wotzlaw et
al.,. 2014) carbonate producing organisms such as corals and clams saw the largest
decline in generic extinction during the Phanerozoic (e.g. Sepkoski 1981; Alroy 2010).
174
The ETE and TJB occurred during the emplacement of the Central Atlantic Magmatic
Province (CAMP), which raised atmospheric CO
2
(Schaller et al., 2014; Knobbe and
Schaller 2018; Steinthorsdottir et al., 2011, McElwain et al., 2009) and led to a cascade of
effects such as warming, ocean anoxia, and ocean acidification that likely led to the ETE
(e.g. Greene et al., 2012; van de Schootbrugge et al. 2013; Bond and Wingall, 2014).
During the Early Jurassic and first stages of the marine recovery following the ETE,
siliceous sponges occupied the shallow benthic environment, effectively replacing
carbonate-producing corals where they typically occurred (Ritterbush et al. 2014;
Ritterbush et al. 2015). Ritterbush et al (2014) hypothesized that high silicic acid
concentrations in the global oceans, inferred from the presence of desmid spicules and
globally significant presence of sponges in the shallow benthic environment in the Early
Jurassic, were a result of the rapid weathering following CAMP and associated delivery
of DSi to the oceans. Sponges may have been able to exploit high DSi in the shallow
marine benthic environment until subsequent drawdown of DSi and re-establishment of
carbonate producing organisms approximately 1.5 Ma later (Ritterbush et al. 2014).
Although Ritterbush et al. (2014) invoke the dominance of sponges in the shallow marine
environment as indicative of high silicic acid concentrations, Alvarez et al. (2017) found
no relationship between the DSi concentration of a water mass and the presence of
siliceous sponges in the modern ocean, raising the question of whether the presence of
siliceous sponges in the Early Jurassic is indeed due to increased silicic acid
concentrations or instead some other biogeochemical or paleobiological factor.
The stable isotope ratio of silicon (δ
30
Si) in sponge spicules reflects the DSi of
water in which the sponges grow (Wille et al., 2010; Hendry et al., 2010; Hendry and
175
Robinson, 2012). DSi is the main factor determining the isotopic compositions of sponge
silicon isotopes across a broad range of depths, nutrient regimes, and temperatures (Wille
et al., 2010; Hendry et al., 2010; Hendry and Robinson, 2012). These studies all
demonstrate that the magnitude of the Si isotope fractionation factor (
30
ε) between
dissolved silica in seawater (δ
30
Si
SW
) and sponge spicules (δ
30
Si
sponge
) is larger when DSi
is higher, leading to a negative relationship between δ
30
Si
sponge
and DSi. Thus analyses of
δ
30
Si may offer a semi quantitative way to reconstruct DSi in deep time, assuming ancient
sponges share the sensitivity of
30
ε to DSi that is observed in modern sponges and that
δ
30
Si
SW
has stayed at a relatively stable value similar to that of modern seawater
throughout Phanerozoic time.
Here, we use this proxy to address two major questions about the Phanerozoic
silica cycle: 1) what was the DSi of the oceans at 200 Ma, prior to dominance of diatoms
but after evolution of radiolarians? and 2) how did DSi evolve in association with CAMP
and the ETE? We measured the silicon isotope composition of sponge spicules
(δ
30
Si
sponge
) via secondary ion mass spectrometry (SIMS) from the well-dated site
spanning 4 Ma around the Triassic-Jurassic Boundary near Levanto, Peru (Fig 1a-b). We
also measured biogenic sponges and inferred chert originating as biogenic sponge
material from the Malpaso Triassic-Jurassic boundary section in Central Peru. Our
observations suggest low DSi (similar order of magnitude as the modern ocean) in the
ocean 200 million years ago, perhaps drawn down by sponge and radiolarian activity and
in contrast with the prevailing hypothesis of high DSi in the Mesozoic. We also find a 0.5
per mil increase in the δ
30
Si of sponge spicules across the Triassic-Jurassic Boundary,
which may indicate drawdown in DSi during the Early Jurassic relative to the Late
176
Triassic, in contrast to the hypothesis proposed by Ritterbush et al. (2014) of high DSi
fertilizing sponge growth. We suggest that either siliceous sponge spicules were
occupying a temporarily unfilled niche and drawing down silicic acid in the ocean or that
a secular change in the sources of DSi occurred during the Late Triassic and Early
Jurassic which changed the silicon isotope composition of DSi.

5.2. STRATIGRAPHIC SECTIONS AND SAMPLES
Siliceous spicules in thin sections from the stratigraphic section near Levanto,
Peru (Yager et al., 2017) and siliceous sponge spicules and silica inferred to be originally
biogenic sponge material from Malpaso, Peru (Ritterbush et al., 2014) were measured in
this study. See the supplemental information for detailed stratigraphy and discussion of
how the sections relate to one another. Other sections were screened for presence of
siliceous sponge spicules, without success. The Levanto section has well-defined absolute
chronology from ash bed dates. While the Malpaso section does have any absolute
chronology or chemostratigraphy, the two samples from this section are almost certainly
from the Hettangian. Since we are unable to further constrain their age, we do not plot
them against time. Samples were screened for analysis using thin sections from sample
o 0 7 o 5 7 o 0 8
5 o
10 o
15 o
Lima
0 250 km
ECUADOR
BRAZIL
BOLIVIA
Pucara Group
200 Ma
CAMP CAMP
Levanto
Levanto
Malpaso
Malpaso
B
A
Figure 1. A: Simplified geolog-
ic map of the Pucará group and
positions of the Levanto and
Malpaso sections, from Ritter-
bush et al., 2015. B: Triassic-Ju-
rassic paleogeography from
Kuroda et al., 2010.
177
sets (see SI Table 1) and targeting samples with siliceous sponge spicules making up
>~5% of a sample.

5.2.1. Levanto, Peru
We analyzed four samples containing quartz sponge spicules from the Levanto,
Peru section, in Aramachay Formation of the Pucara group in the Peruvian Andes. The
Levanto section has high-resolution U-Pb dating (Guex et al., 2012; Schaltegger et al.,
2008; Schoene et al., 2010; Wotzlaw et al., 2014) and contains the highest absolute age
dating resolution for the Triassic-Jurassic Boundary. The section is relatively deep (well
below storm wave base) and the lithology changes little over the four-million year
continuous section (Yager et al., 2017). Carbonate-rich mudstones house numerous
carbonate-replaced radiolarians and rare siliceous spicules now preserved as quartz. We
used the samples and age model from Yager et al. (2017) to plot δ
30
Si data against time in
this study.
Spicules found in the Levanto samples are now quartz and we measured spicules
that were distinct from any surrounding matrix (Fig 2). Although diagenesis certainly
occurred during the transformation from opal-A to quartz, it would be exceptionally
serendipitous for silica to completely leave a spicule and to return to it, and we therefore
assume no fractionation from opal-A to quartz formation. Additionally, silicon isotopes
are likely more resistant to alteration during diagenesis (Marin-Carbonne et al., 2011;
Stefurak et al., 2015).
We interpret spicules with a clear boundary between the matrix and spicule as
primary. Spicules may have been transported to the site of deposition from further up the
178
slope, and multiple spicules in thin section probably preserve a range of temporal and
individual sponge information, but we interpret them as broadly reflecting a characteristic
δ
30
Si value.

5.2.2. Malpaso (Central Peru)
The Malpaso section is also part of the Pucará group and is typically comprised of
the Late Triassic Chambará formation and overlying Aramachay Formation, which
contains the Triassic-Jurassic Boundary in the Levanto section and may record it
elsewhere. In contrast to the mudstones at Levanto, the Aramachay at Malpaso is
dominated by carbonates. One ash bed age from the nearby site at Gavilan (unpublished
data) puts a tuff seen in Ritterbush et al. (2015) as near the Hettangian-Sinemurian
Boundary. The two samples used in this study occur below either of the Malpaso tuffs,
and are assumed to occur within the Hettangian. Without better age constraints it is not
possible to fit these into a broader context with the Levanto section.
The preservation of sponge spicules seen in the Malpaso section varies widely. In
some cases siliceous spicules are found in siliceous matrix (Fig 2 C-D) and in other cases
spicules are replaced with carbonate and are in a matrix of silica. We assumed the silica
and carbonate migrated during early fluid flow diagenesis and measured the δ
30
Si of the
matrix in this case (SI Fig 2).

179
5.3. METHODS
5.3.1. Sample preparation
The silicon isotope composition (δ
30
Si) of sponge spicules is typically measured
via multicollector inductively coupled mass spectrometry (MC-ICP-MS) by dissolving
20-30 cleaned spicules (Wille et al., 2010; Hendry et al., 2010). Here, siliceous sponge
spicules were rare in investigated samples, and we measured δ
30
Si via secondary ion
mass spectrometry (SIMS) since separation of spicules from lithified samples would
require HF treatment (at least for the mudstones from Levanto) and in any case would be
unlikely to yield enough (20-30) spicules in a given sample to run via MC-ICP-MS.
SIMS specific mounts were prepared by cutting rock samples with spicules observed in
thin section parallel with bedding (to maximize spicule surface area) and mounting them
in 1” rounds with standards (Caltech Rose Quartz and NBS28). We made whole thin
section maps of each sample prior to SIMS analyses and identified siliceous spicules of
interest.
In order to ground truth methods and assure this study is comparable to previous
work on δ
30
Si of sponges (with measurements made by MC-ICP-MS), six modern
sponges from water with known DSi from the Los Angeles Natural History Museum
Invertebrate Collection and one sponge from a cruise track from the Santa Monica Basin
were also prepared for SIMS analysis. These sponges were cleaned and dissolved
following Hendry et al. (2010). We heated a subset of spicules from each modern sponge
sample to 500ºC in a furnace for 12 hours and mounted both the clean, unheated spicules
and the heated spicules with standards on SIMS mounts. Spicules from unheated and
heat-treated subsets were analyzed via Raman spectroscopy at the Los Angeles Natural
180
History Museum in order to compare mineralogy before (opal-A) and after (opal-CT)
heating (see supplemental information). SIMS can be highly sensitive to matrix effects
(e.g. Gabitov et al. 2013; Slodzian et al. 1980; Steele et al. 1981) and the matrix effects of
silica phases have not been previously characterized. Although we do not expect isotopic
exchange to have occurred during only heat treatment, these heat treated samples enabled
us to evaluate these potential matrix effects and determine whether SIMS δ
30
Si values of
modern opal-A spicules can be directly compared with ancient quartz spicules (i.e.,
Triassic-Jurassic samples).

5.3.2. SIMS analyses
Silicon isotope measurements were measured via Secondary Ion Mass
Spectrometry (SIMS) at the California Technical Institute Microanalysis center using the
Cameca IMS-7f-GEO ion microprobe at the Caltech Microanalysis Center (California
Institute of Technology, Pasadena, CA) over three sessions (November 2017, August
2018, and February 2019). For each spot analysis a 9 kV beam of O
-
was focused to a 20-
30 um spot on the sample surface, effectively encompassing the width of a spicule. Count
rates were usually between 5-7 x 10
7
counts/s, and total analysis time for each analysis
was 8 minutes (including 60s pre-sputtering, field and beam centering, and 20 cycle
analyses). 282 total spot analyses were collected from quartz spicules from Levanto and
67 total analyses were collected from inferred biogenic sponge material from Malpaso.
Sample measurements were bracketed by standard suites of Caltech Rose Quartz and/or
NBS28, and δ
30
Si was calculated for each sample by normalization to these standards
(both defined as 0‰; δ
30
Si =((R
sample
/R
NBS-28/RQ
)-1) x 1000).
181
5.3.3 Data reduction
Raw ratio data within a single spot analysis that was >2SD from the mean of an
analysis was removed for each analysis. δ
30
Si values were calculated following Kita et al.
(2009). Each spicule was observed for preservation type (“clear”, “brown”, “large”) and
each analysis point was observed to see if the entire analysis fell on/off the spicule or
within an axial filament. All analyses with a standard deviation >.25 were removed. All
analyses are reported in the supplementary data tables, with spicule preservation type and
analysis quality indicated (see supplemental information for examples of preservation
types).

5.4. RESULTS
5.4.1 Modern sponge spicule δ
30
Si
This study is the first to report δ
30
Si analyses on sponge spicules by SIMS, allowing
in situ analysis and thus a means to evaluate variability within individual spicules. We
observed inter-spicule variability of up to 1.5‰ (SD) which is well outside of analytical
uncertainty of ~0.3‰, and in some cases this variability was observed along a long axis
(Figure 2). We measured four modern sponge spicules via SIMS, some of which are from
182

locations with known DSi concentrations, which are reported in Figure 3. Like the
Triassic-Jurassic Boundary spicules, modern sponge spicules exhibit variability within
spicules. Sponge spicule type has recently been observed to affect the isotopic
fractionation associated with the sponge silicon isotope value, with ‘fused’ spicule
structures innapropriate for the DSi proxy (Cassarino et al., 2018). We observed
variability within modern sponges of up to 5‰, but these specimens were fused sponges
and thus not a reliable record of DSi. This also suggest high variability within fused
sponges may be due to the high variability within single specimens. The smallest
variability within a single sponge was ~1‰ (from santa Monica Basin, Fig 3). All the
Figure 3. δ
30
Si results from four modern sponges. Note variability ranges from
~1‰ to almost 5‰. Sponges B and D are from fused spicule strucutre sponges,
and their high variability may be a product of that spicule structure.
δ
30
Si‰
δ
30
Si‰
~100 μM
Santa Monica Basin
Hexact.
311-351m
near Catalina Isd.
~10-20 μM
Venus comb
Sulu Sea
Hexact.
210-320m
near Catalina Isd.
-6
-4
-2
0
2
-6
-4
-2
0
2
A B C D
183
modern sponges measured were from single individuals, while Triassic-Jurassic boundary
spicules are likely transported from multiple individuals. This suggests variability within
Triassic-Jurassic boundary samples is normal, and may also support the lack of
diagenetic influence on Levanto spicules.

5.4.2. Mesozoic sponge spicule δ
30
Si
We report δ
30
Si values plotted against time in Figure 4. Each analysis is reported
in Fig 4 and in SI Table 1. Sponge spicules exhibit intra and inter-spicule variability in
each sample (Fig 2). Results are reported by spicule in SI Table 1 and data is displayed
on example spicules in SI Figs 1-8. External error for a single analysis is on average
0.53‰ and internal error is on average 0.22‰.
Sample LV17 (~203.9 Ma) has an average value (each analysis weighted equally)
of -0.90‰ and an average value of -1.00‰ (each spicule weighted equally). Sample
LV49 (~202.8 Ma) has an average value (each analysis weighted equally) of -1.24‰ and
an average value of -1.21‰ (each spicule weighted equally). Sample LV78 (~202.1 Ma)
has an average value (each analysis weighted equally) of -0.18‰ and an average value of
-0.06‰ (each spicule weighted equally). Sample LV149 (~200.9 Ma) has an average
value (each analysis weighted equally) of +0.42‰ and an average value of +0.37‰ (each
spicule weighted equally).
In general, a first order increase in δ
30
Si is observed across the measured interval.
Maplaso results for sample M06 have an average δ
30
Si value of -1.23 ± 0.80‰ (1 SD)
and for sample MP4 have an average δ
30
Si value of -0.11 ± 0.41 (1 SD)
184
In summary, Levanto spicules and Malpaso inferred biogenic silica isotopic
analyses largely fall between -3.0‰ to 2.0‰, comparable to modern and Paleogene δ
30
Si
measurements from sponge spicules, which span approximately -6.0 to 1.0‰ (modern
sponges are found in waters with 10-200uM DSi).

Figure 4. δ
30
Si results from Levanto, Peru spicule
analyses displayed with time. CAMP U-Pb ages
are also shown (Davies et al., 2017). Additional
data from Malpaso are shown but not plotted
versus time because of the lack of age control,
though they are very likely Hettangian. Note that
CAMP U-Pb ages fall between samples LV78
(~202.1 Ma) and LV149 (~200.9 Ma).
all analses
samle aeraes S
Malaso all analses
liel ettanian
-4
-2
0
2
4
201 202 203 204
-4
-2
0
2
4
urassic riassic
δ
30
Si‰
δ
30
Si‰
CM -b
185
5.5. DISCUSSION
5.5.1. Low marine silica concentrations during the Triassic-Jurassic Boundary
Using the sponge spicule δ
30
Si proxy as it would in the modern, the absence of very
fractionated (e.g. <-4.0‰) silicon isotope measurements from sponge spicules leads us to
interpret the mid-Mezosoic depositional environment (where sponges were growing) as
one with lower DSi, and thus more similar to the modern ocean than has been proposed.
Alternatively, the δ
30
Si
SW
could have been substantially different during the Triassic-
Jurassic Boundary. We have no reason to suspect that fractionation in sponges would
have been wildly different in the past, but we cannot rule out this possibility. Changes in
the δ
30
Si of seawater could also play a role in determining the composition of sponge
spicules, as discussed below, so if oceanic compositions were dramatically different at
~200 Ma, it is possible that the similarity between modern and Mesozoic sponge spicule
δ
30
Si is coincidental.
If DSi in the mid-Mesozoic was similar to the modern, as we suggest based on our
data, radiolarians and/or sponges must have been more effective at drawing down silica
than has been thought based on diatoms being the dominant players in the marine Si
cycle today. If correct, views of the evolution of marine silicifiers and the Si cycle merit
reconsideration (Fig. 5).

5.5.2. Changes in the marine silica cycle in the aftermath of extinction across the
Triassic-Jurassic Boundary
Late Triassic sponge spicules from Levanto have average δ
30
Si ca. -1.0‰, rising
to ca. 0.5‰ during the Early Jurassic. This first order shift towards heavier δ
30
Si across
186
the Triassic-Jurassic Boundary could be explained by higher concentrations of DSi in the
Late Triassic and lower concentrations in the Early Jurassic. Widespread stratigraphic
observations show increased sponge spicule material during the Early Jurassic. Sponges
may have expanded rapidly following the ETE, benefitting from niche availability
following ocean acidification and carbonate collapse (Ritterbush et al., 2014). A decrease
in DSi might be explained by these sponges drawing down DSi during the early Jurassic.
Benthic sponges may have drawn down DSi more effectively than radiolarians due to
their recalcitrance during transport and early diagenesis (Bertolino et al., 2017; Uriz,
2006). This may indicate that sponges perhaps had a larger role in drawing down DSi in
the mid-Mesozoic than previously understood, or that another Si user was drawing down
Si (such as picoplankton, see Krause et al., 2017) that is as currently under considered
during the Mesozoic.

187
An alternative explanation for the increase in δ
30
Si during the Early Jurassic could
be an ocean-wide shift in the isotopic composition of dissolved silicon in the ocean. Such
a change might be driven by climatic shifts altering reverse weathering and therefore
seawater δ
30
Si or changes in inputs (de la Rocha and Bickle, 2005; Frings et al., 2016).
Both occurred across the Triassic-Jurassic Boundary (increased CO
2
from CAMP
magmatism and associated weathering), so a change in the δ
30
Si of the oceans is plausible
at this time. However, constraining the isotopic signal of inputs to the Triassic-Jurassic
Boundary oceans is not straightforward: fractionation of δ
30
Si also occurs during clay
formation in soils and during riverine transport (Georg et al., 2006), which is not well
constrained at the time. Furthermore, precisely what type (e.g. warming or cooling) of
climatic shift across the Triassic-Jurassic Boundary occurred is still debated (see Bond
and Wignall, 2014 for a review). Thus we are unable to constrain potential shifts in the
δ
30
Si of DSi and how they may have affected the δ
30
Si of sponge spicules from Levanto.
In the modern ocean, radiolarians have an estimated fractionation factor of between -1‰
and -2‰ from their DSi pool (Hendry et al. 2014). Measuring radiolarian δ
30
Si across the
same interval may help distinguish between a change in the δ
30
Si
DSi
or the concentration
of DSi.

5.6. CONCLUSIONS
δ
30
Si measurements on sponge spicules from 4 million years spanning the
Triassic-Jurassic Boundary exhibit isotopic values similar to modern sponge spicules (-3
to 2‰), which suggest mid-Mesozoic silica concentrations in the ocean may have been a
similar order of magnitude to the modern ocean. In contrast to the prevailing hypothesis
188
that radiolarian and sponge-dominated oceans during Earth’s history were unable to draw
down DSi, we hypothesize that the Late Triassic and Early Jurassic were characterized by
DSi concentrations similar to the modern, diatom-dominated ocean. Furthermore,
Triassic-Jurassic boundary δ
30
Si from sponge spicules suggest that the massive
perturbation to the carbon cycle may have opened up niche space in the shallow benthic
environment, allowing sponges to gain a foothold and potentially draw down DSi in the
Early Jurassic ocean.

189
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5S: SUPPLEMENTAL INFORMATION FOR CHAPTER 5

Siliceous sponge spicules begin as opal and transform into quartz during
diagenesis. In samples from the Triassic-Jurassic Boundary, siliceous sponge spicules are
rare based on our petrographic observations. Only in rare samples were enough siliceous
sponge spicules present to warrant prep for SIMS analyses (typically >15 qtz
spicules/sample). These were prepped for SIMS via new billets being cut at
approximately 1cm/1cm size targeting the portion of the sample where spicules were
found. We prepped samples parallel to stratigraphy and parallel to bedding, and found
that samples prepped parallel to bedding allowed for maximum spicule area and were
therefore more desirable for SIMS analyses.

5S1. Spicule preservation types and SIMS analysis sorting
Each spicule and analysis point were investigated petrographically after SIMS
analyses to see if there was a systematic difference in silicon isotope composition
depending on the spicule preservation style or on the part of the spicule analyzed (e.g.
intersecting an axial filament), and to ensure analyses were predominantly on the spicule.
Overall, no systematic differences were observed between spicule preservation types.
We identified three predominant types of spicule preservation: ‘clear’ spicules
(Fig 1), ‘small brown’ spicules (Fig 2), and ‘large brown-black’ spicules (Fig 3). In one
case we also found a red rind on a spicule which was anomalously variant (Fig 4; we
removed both analyses). We also made notes on the individual analyses, noting (1) the
type of spicule preservation (some spicules displayed multiple preservation types within
198
the individual spicule, e.g. Fig 5,6), (2) if the analysis intersected an axial filament (Fig 6)
and (3) if the analysis was completely on the spicule or fell off of it to some extent (Figs
7-8). In some cases matrix obscured the spicule during petrographic observation and it
was difficult to determine whether individual analyses fell on a spicule or not (Fig 7-8).
However, in most cases with reflected light imaging it was possible to determine if an
analysis was predominantly on a spicule.
There is some indication that analyses falling off spicules tended to be more
negative; however, in many cases what appeared to be off the spicule in plane polarized
light looked like the analysis was on the spicule in reflected light. This is a product of the
analysis and spicule geometry and the limitations of a thin section that is ~30 µm thick,
depended on the matrix how clear the spicule boundaries were in plane polarized light.
Thus we hesitate to make definitive evaluation of the effect of spot positioning but have
eliminated obviously problematic individual analyses (represented in grey in the data
tables; total 19 out of 339 analyses) and rely on the large number of total analyses to
average uncertainties associated with preservation, spot positioning, and intra-spicule
variability.

5S2. Raman spectroscopy
We attempted to heat modern sponge spicules to 500ºC to simulate diagenesis and
potentially transform spicules from opal-A to opal-CT. However, organic molecules in
the unheated samples obscure the Raman spectra, and heated samples are still opal-A (Fig
S10). We may get a difference in the δ
30
Si composition of the heated and unheated
samples due to the organic molecules on the unheated samples. In the heated sample,
199
Raman spectra mostly show background flourescenced, which is likely caused by an
array of organic compounds within the specula (Fig S11). The fluorescence is what gives
the spectrum high intensity. After heating, the organics burn off and we get a reasonable
opal-A spectrum. The organics are gone and we get an opal pattern.

200
0.6
0.8
1
1.2
1.4
1.6
δ
30
Si‰
-1.6
-1.4
-1.2
-1
-0.8
-0.6
-0.4
-0.2
30
Si= -1.31±1.88‰
-2.64±0.62‰
0.21±0.62‰
Figure S1 (left). LV17F, spicule 14: example
of clear spicule preservation in plane polar-
Figure S2 (below). LV149F, spicule 2.
Example of brown spciule preservation.
eft plane polaried light. ight δ
30
Si‰
Figure S3 (above). LV49F, spicule 6.
Example of large spciule preservation.
Figure S4 (left). LV149F, spicule 6. This
spicule has a red rind and we removed the
silicon isotope data.
δ
30
Si‰
201
-0.5
0
0.5
1
Figure S7 , spicule 1 δ
30
Si‰: demonstrates spatial relationship between
spicule at surface where analysis is made and within 30 um depth thin section.
Left: reflected light image with analysis points clearly visible. Center of spicule is
in places a different relief. Right: plane polarized image with isotope analyses
(color coded).
Figure S8: LV17F, spicule 1 as an example of analyses that lie off the spicule
and were removed. Left: cross polarized light image with spicules outlined.
Note matrix is also siliceous. Right: plane polarized light image with spicules
outlined - spicules are difficult to see and analyses clearly intersect the matrix.
202
0.4
0.6
0.8
1
δ
30
Si‰
-2
-1.5
-1
-0.5
Figure S6. 4, spicule 1 δ
30
Si‰. Composite images of spicule 1. In this spicule
several preservation types are observed (clear, brown, and unknown) with no system-
atic isotopic offset.
clear
Figure S5. LV149F, spicule 5. An example of two preservation styles within the
same spicule but no systematic isotope effect. eft plane polaried light. ight δ
30
Si‰ results
dark
dark
203
Figure S9: Stratigraphic columns from Levanto, Peru (Yager et al., 2017), New York Canyon (Thibodeau et al.,
2016) and Malpaso section and nearby Gavilan section (Ritterbush et al., 2015). We estimate that the two
Malpaso samples used in this study are Hettangian in age based on an unpublished age bed date from the
Gavilan section, which may correlate with the lower ash bed in the Malpaso section. The base of the Malpaso
section seen here is typically regarded as the Triassic-Jurassic boundary based on formation change.
cher cher r b ows
ooids
. silica
. . silica
. Cerro Gavila 0
15
30
45
60
75
90
105
120
135
0
15
30
45
60
recr ed
Ke 199.217±0.059 Ma
M4sponge
LV17
LV49
LV78
LV149
M6sponge
Extinction
interval
Pre-extinction
Depauperate
interval
metazoan silica
metazoan
carbonate
0
10
20
30
40
50
60
70
m
Microfacies
No fossils
Spiculite
In situ sponges
Abundant CaCO
3
shells
CAMP ?
0
20
40
60
80
100
Triassic
204
Figure S10: Unheated modern spicule Raman spectra
500 1000 1500
0
5000
10000
15000
20000
25000
Raman Shift (cm
-1
)
Intensity (cps)
unheated-5
unheated 3 SMB core
unheated 5 hex chur
unheated 9
unheated 11
500 1000 1500
0
5000
10000
15000
20000
25000
205
500 1000 1500
0
200
400
600
800
1000
1200
1400
Raman Shift (cm
-1
)
Intensity (cps)
heated-5
heated 3 SMB core
heated 5 hex chur
heated 9
heated 11
Figure S11: Heated modern spicule Raman spectra
206
Chapter 6. Conclusions

6.1. A SYNTHESIS OF LEVANTO SECTION DATA AND INTERPRETATIONS
In figure 1, I summarize the geochemical results from the Levanto section
(chapters 2-5) along with CAMP U-Pb ages (Davies et al. 2017). Major biogechemical
change occurs in the 2.5 million years leading up to the end-Triassic extinction, which
has largely been overlooked prior to this work. This thesis presents the first high-
resolution, absolute dating age constrained records of δ
13
C
org
, δ
13
C
carb
, δ
15
N, trace metals,
Hg concentrations and isotopes spanning ~204 through ~200 Ma. Taken together, these
results suggest a possible increase in oxygenation prior to the ETE affects the global C
cycle prior to CAMP emplacement, and that a dramatic change in redox coincides with
CAMP emplacement and CO
2
rise during the ETE. Hg results suggest a more
complicated picture for the Hg proxy, and one that lithology must be taken into account
for. This thesis also reports the first silicon isotope measurements on sponge spicules
from the Mesozoic, and suggests low silicic acid concentrations during the mid
Mesozoic.

6.1.1. Linking the Levanto section and end-Triassic extinction to the modern
If, as suggested here, the Levanto section does record an increasingly oxygenated
ocean prior to the end-Triassic extinction and silica concentrations in the ocean similar to
today’s, one finding of this work is that the Triassic-Jurassic boundary ocean was more
similar to today’s than previously understood. Corroborating this evidence is the
abundance of carbonate in the Levanto section, which arguably should have been affected
207
by the ETE (e.g. Greene et al 2012) or not present at all based on ideas about the
carbonate cycle 200 million years ago (e.g. Ridgwell et al 2005).

6.1.2. The potential role of basin restriction at the Levanto section
One underexplored avenue with respect to the Levanto section is the potential role
of basin restriction on proxies measured here. In chapter 5, I discussed the role that
carbonate dilution and/or Hg migration plays in the Hg and Hg/TOC proxy at the Levanto
Figure 1. Summary of data presented from the Levanto section in this thesis,
plotted with time and CAMP U-Pb age dates from Davies et al., (2017).
-30
-28
0
5
10
200.5 201 201.5 202 202.5 203 203.5 204
0
200
400
V (ppm)
Jurassic
0
50
100
150
Hg/TOC
CAMP U-Pb
0
201 202 203 204
age (Ma)
-4
-2
0
2
Triassic
0.1
-0.1
199
Hg‰
δ
15
N‰
δ
13
C
org
‰
δ
30
Si‰
208
section, noting that this occurs during a transition in organic C isotopes. This also co-
occurs with the first low V sample, indicating either a dramatic change in basin
restriction or that the change in diagenetic processes at Levanto coincided with a major
expansion in ocean anoxia. In appendix B I report osmium isotope measurements from
the Levanto section, which may suggest some degree of restriction to the Levanto
section. However, we cannot ignore the presence of ammonites and radiolarians in the
outcrop and thin sections, indicating a normal marine environment for much of the
depositional section. Additional analyses, for example Nd isotopes, may help elucidate
the degree of basin restriction from the Levanto section and its potential role in changing
geochemical data presented here through time.

6.1.3. Next steps and future avenues
The sulfur cycle at the Levanto section is almost completely unexplored. In
Appendix E, I report a high resolution SEM/EDS map displaying relative element
abundance from sample LV78. In low oxygen settings, we expect some pyrite formation;
however, at the Levanto section little pyrite is preserved (if any). S concentrations as a
future research direction would help elucidate the putative euxinic interval and help
understand any potential association between Hg and S.
Appendix E also highlights the presence of phosphorus in sample LV8. Like the
Miocene Monterey Formation, the Levanto section preserves P nodules within the
sediments, in particular during the Rhaetian that resemble the Monterey Formation (Fig 2
for a visual comparison). Measuring P, either in bulk, partially separated, or fully
209
separated would be an interesting further component and understanding of changes in
nutrients during this interval, particularly during the Rhaetian.

Compound specific C isotopes (Ruhl et al., 2011) suggest changes in organic C
isotopes associated with the ETE are due to atmospheric changes. We hope to measure
compound specific C isotopes from the Levanto section to see if this corroborates or
refutes this idea. Furthermore, biomarkers may help with understanding the role of
euxinia at the Levanto section and whether it is restricted to the sediments or water
column and differentiate between bottom water and water column euxinia (as seen in
Kasprak et al., 2015). The Levanto section may preserve biomarkers, since rock eval
(Appendix C) data suggest heating was not too super hot. Additionally, ramped pyrolysis
also suggests some labile organic matter is left. I received funding from the EAOG to
measure biomarkers and plan to with Julio Sepulveda and Sarah Feakins following the
defense of this thesis.
Figure 2. Similarities
between the Monte-
rey Formation
(Miocene; Left) and
Levanto section
(right).
P nodule
laminated
laminated
P nodule
10 cm
210
Silicon isotope diagenesis from Icelandic spring deposits suggest major
fractionation during opal a to opal CT transformation (Jones and Renaut, 2007; Geilert et
al., 2014); however, this is a very different system than spicule preservation seen during
the Triassic and Jurassic. The Miocene Monterey Formation may also be an avenue to
explore silicon isotope diagenesis, since the transformation of opal-a to opal-ct to quartz
is well documented there and the diagenetic changes with oxygen isotopes that
accompany this process. All we need is somewhere to run these!

6.1.3.1. Decoupled C isotope records across the Triassic-Jurassic boundary?
In Chapter 2, I reported paired inorganic and organic C isotopes from the Levanto
section. Italian records of inorganic and organic C isotopes also suggest decoupled
records, but do not go into the Rhaetian. Decoupled records have a big effect on
modeling studies, and an outstanding question is whether this decoupling is truly global.
We have δ
13
C
org
and δ
13
C
carb
measurements underway from several other sections
within a lithologic and diagenetic framework to try and untease this decoupling.
Additionally, the Rhaetian nitrogen isotope trend seen at Levanto and other records
(Chapter 3) suggest a shift. However, additional high resolution records from other
paleogoegraphic locations will help us understand weather this is a local or global signal.
We have collected samples from Italy and hope to run nitrogen isotopes on these to better
understand the Triassic-Jurassic boundary nitrogen cycle.

This thesis also generates some more outstanding questions about the Triassic-Jurassic
boundary:
211
• What effect (if any) did the potential sponge drawdown and radiolarian gap have
on organic matter burial and the C cycle?
• What role does S and anoxia play in the cycling of Hg in the ocean and
preservation of Hg in the marine sedimentary record?
• How does the migration and/or trapment of Hg during deposition and diagenesis
effect Hg isotopes?
• What is the role of anoxia and/or euxinia at the Levanto section with respect to
δ
13
C
org
, and what is the role of anoxia/euxinia globally on the C cycle during the Late
Rhaetian and ETE?

This thesis has constrained the durations of some of the changes in ocean
chemistry and provided more quantitative evidence for redox and the silica cycle in the
Triassic-Jurassic oceans. Ongoing work will continue to address the questions presented
above.

212
REFERENCES
Davies, J H F L, Marzoli, A., Bertrand, H., Youbi, N., Ernesto, M., & Schaltegger, U.
(2017). End-triassic mass extinction started by intrusive CAMP activity. Nature
Communications, 8, 15596. doi:10.1038/ncomms15596
Geilert, S., Vroon, P.Z., Roerdink, D.L., Cappellen, P.V., van Bergen, M.J., 2014, Silicon
isotope fractionation during abiotic silica precipitation at low temperatures:
Inferences from flow-through experiments, Geochimica et Cosmochimica Acta, v.
142, p. 95-114.
Greene, S. E., Martindale, R. C., Ritterbush, K. A., Bottjer, D. J., Corsetti, F. A., &
Berelson, W. M. (2012). Recognising ocean acidification in deep time: An
evaluation of the evidence for acidification across the triassic-jurassic
boundary. Earth-Science Reviews, 113(1-2), 72-93.
doi:10.1016/j.earscirev.2012.03.009
Jones B. and Renaut R. W. (2007) Microstructural changes accompanying the opal-A to
opal-CT transition: new evidence from the siliceous sinters of Geysir, Haukadalur,
Iceland. Sedimentology 54, 921–948.
Kasprak, A. H., Sepúlveda, J., Price-Waldman, R., Williford, K. H., Schoepfer, S. D.,
Haggart, J. W., . . . Whiteside, J. H. (2015). Episodic photic zone euxinia in the
northeastern panthalassic ocean during the end-triassic extinction. Boulder:
Geological Society of America, Inc. doi:10.1130/G36371.1

213
Ridgwell, A., 2005, A Mid Mesozoic Revolution in the regulation of ocean chemistry,
Marine Geology, V. 217, p. 339-357.
Ruhl, M., Bonis, N.R., Reichart, G-J., Damsté, J.S.S., Kürschner, W.M., 2011,
Atmospheric Carbon Injection Linked to End-Triassic Mass Extinction, Science v.
333, no. 430 DOI: 10.1126/science.1204255.

214
Appendix A: Overview thin section photomicrographs from
the Levanto section

A.1. IMAGES
Levanto section overview images are displayed here. All images were acquired
under the same settings, so that color differences between samples are due to sample
differences (although note this may include thin section thickness) and not due to settings
differences. All images are 25x magnification and in all cases the orientation of the image
was intended to be in the up direction. Images are displayed in stratigraphic order (e.g.
see sample list with meters in Appendix G. I attempted to acquire images that were
representative of the sample.
Each sample was assigned a number (1, 2 or 3) designating a broad lithologic
category from thin section observations, which I compared to the data reported in
chapters 2-4. This qualitative overview is reported at the end of this appendix. Type 1 is
compacted, radiolarian rich (e.g. Figure 1a), type 2 is uncompacted (e.g. Figure 1b) and
type 3 is other (e.g. Figure 1c), which may include diagenetic carbonates and ash beds.
Types 1 and 2 are likely different due to early diagenesis (e.g. in some cases radiolarians
are preserved as carbonate within compacted settings, other times radiolarians are not or
may be preserved as silica).

215
LV1 LV2
LV3 LV4
LV5 LV6
LV7 LV8
00 m all images
216
LV10 LV11
LV12 LV13
LV14 LV15
LV16 LV17
00 m all images
217
LV23
LV25
LV18
LV20
LV22
LV24
LV26
LV21
00 m all images
218
LV27
LV29
LV31
LV34
LV28
LV30
LV35
LV33
00 m all images
219
00 m all images
LV36
LV38
LV40
LV42
LV37
LV39
LV41
LV43
220
00 m all images
no image
LV48
LV50
LV44
LV46 LV47
LV49
LV51
LV45
221
00 m all images
LV52
LV54
LV56
LV58
LV53
LV55
LV57
LV59
222
00 m all images
LV60
LV62
LV64
LV66
LV61
LV63
LV65
LV67
223
00 m all images
LV68
LV70
LV72
LV74
LV69
LV71
LV73
LV75
224
00 m all images
LV76
LV78
LV80
LV83
LV77
LV79
LV81
LV84
225
00 m all images
LV90
LV82
LV86
LV88 LV89
LV91
LV85
LV87
226
00 m all images
LV92
LV94
LV96
LV98
LV93
LV95
LV97
LV99
227
00 m all images
LV100
LV102
LV104
LV106
LV101
LV103
LV105
LV107
228
00 m all images
no image
LV108
LV110
LV112
LV114
LV109
LV111
LV113
LV115
229
00 m all images
LV116
LV118
LV120
LV122
LV117
LV119
LV121
LV123
230
00 m all images
LV124
LV126
LV128
LV130
LV131
LV125
LV127
LV129
231
00 m all images
no image
LV132
LV134
LV136
LV138
LV133
LV135
LV137
LV139
232
00 m all images
LV140
LV142
LV144
LV146
LV141
LV143
LV145
LV147
233
00 m all images
LV148
LV150
LV153
LV154
LV149
LV151
LV152
LV155
234
00 m all images
LV156
LV158
LV160
LV162
LV157
LV159
LV161
LV163
235
00 m all images
LV164
LV166
LV168
LV170
LV165
LV167
LV169
LV171
236
no image
00 m all images
LV174
LV176
LV178A
LV172
LV173
LV175
LV177
LV178B
237
00 m all images
LV179
LV181
LV183
LV185
LV180
LV182
LV184
LV186
238
no image
00 m all images
LV187
LV189
LV191
LV193
LV188
LV190
LV192
LV194
239
LV195
LV197
LV199
LV201
LV196
LV198
LV200
LV202
240
LV203
LV205
LV207
LV209
LV204
LV206
LV208
LV210
241
LV215
LV217
LV211
LV213
LV214
LV216
LV218
LV212
242
LV219
LV221
LV223
LV225
LV220
LV222
LV224
LV226
243
LV227
244
00 m, all images
A B C
Figure 1. epresentatie thin section oerie images from the eanto section for types 13 lithologies. ig
1a is type 1, ehibiting recrystallied radiolarians, and is the most typical for the eanto section. ig 2b is
interpreted as uncompacted type 2 lithology, and ig 1c is interpreted as diagenetic carbonate and is type 3
lithology.
245
A.2. THIN SECTION CATEGORY DESIGNATIONS
Sample Type Sample Type Sample Type Sample Type Sample Type
LV1 1 LV44 2 LV84 1 LV122 1 LV161 1
LV2 1 LV45 1 LV82 1 LV123 1 LV162 1
LV3 1 LV46 1 LV85 1 LV124 3 LV163 1
LV4 3 LV47 1 LV86 1 LV125 1 LV164 1
LV5 3 LV48 1 LV87 1 LV126 3 LV165 1
LV7 1 LV49 1 LV88 1 LV127 1 LV166 1
LV8 1 LV50 1 LV89 1 LV128 1 LV167 1
LV10 1 LV51 1 LV90 1 LV129 2 LV168 1
LV11 1 LV52 1 LV91 1 LV130 1 LV169 1
LV12 1 LV53 1 LV92 2 LV131 1 LV170 1
LV13 1 LV54 2 LV93 1 LV132 1 LV171 1
LV14 1 LV55 1 LV94 1 LV133 1 LV172 1
LV15 1 LV56 1 LV95 1 LV134 1 LV173 3
LV16 1 LV57 1 LV96 1 LV135 1 LV174 2
LV17 2 LV58 1 LV97 1 LV136 1 LV175 1
LV19 3 LV59 1 LV98 1 LV137 1 LV176 2
LV20 1 LV60 1 LV99 1 LV138 1 LV177 1
LV21 1 LV61 1 LV100 1 LV139 1 LV178A 1
LV22 1 LV62 2 LV101 1 LV140 1 LV178B 1
LV23 1 LV63 2 LV102 1 LV141 1 LV179 1
LV24 1 LV64 1 LV103 1 LV142 1 LV180 1
LV25 1 LV65 1 LV104 1 LV143 1 LV181 2
LV26 1 LV66 1 LV105 1 LV144 1 LV182 2
LV27 1 LV67 1 LV106 1 LV145 1 LV183 2
LV28 1 LV68 2 LV107 1 LV146 1 LV184 1
LV29 2 LV69 1 LV108 1 LV147 1 LV185 1
LV30 1 LV70 1 LV109 3 LV148 1 LV186 2
LV31 1 LV71 2 LV110 1 LV149 1 LV187 1
LV32 1 LV72 1 LV111 1 LV150 1 LV188 2
LV34 1 LV73 1 LV112 1 LV151 1 LV189 2
LV35 1 LV74 1 LV113 1 LV153 3 LV190 2
LV36 1 LV75 1 LV114 1 LV152 1 LV191 2
LV37 1 LV76 1 LV115 1 LV154 1 LV192 2
LV38 1 LV77 1 LV116 1 LV155 1 LV193 2
LV39 1 LV78 2 LV117 1 LV156 1 LV194 1
LV40 1 LV79 1 LV118 1 LV157 1 LV195 2
LV41 1 LV80 1 LV119 1 LV158 1 LV196 1
LV42 2 LV81 1 LV120 3 LV159 1 LV197 1
LV43 1 LV83 1 LV121 1 LV160 1 LV198 1
246
Sample Type
LV199 2
LV200 1
LV201 1
LV202 2
LV203 1
LV204 1
LV205 2
LV206 1
LV207 2
LV208 1
LV209 1
LV210 1
LV211 1
LV212 1
LV213 1
LV214 1
LV215 1
LV216 2
LV217 1
LV218 2
LV219 1
LV220 2
LV221 1
LV222 2
LV223 1
LV224 2
LV225 1
LV226 1
LV227 2
247
Appendix B. Inconclusive osmium isotopes from the
Levanto section

B.1. OSMIUM AS A POTENTIAL TRACER OF CAMP MAGMATISM
In addition to Hg concentrations and isotopes (e.g. discussed in Chapters 1 and 4),
187
Os/
188
Os is a potential tracer of mantle-derived material from CAMP and subsequent
weathering of more radiogenic material following increased atmospheric CO
2
addition.
Seawater
187
Os/
188
Os reflects the balance between continental crust input (
187
Os/
188
Os
~1.3; radiogenic
187
Os originates from the decay of
187
Re, and
187
Re is enriched in the
crust compared to the mantle) and mantle input (
187
Os/
188
Os~0.13) (Shirey and Walker,
1998; Peucker-Ehrenbrink and Ravizza, 2000). Changes in the
187
Os/
188
Os ratio through
time therefore reflect changes in the inputs of mantle vs continental weathering. Large
igneous province volcanism, like CAMP, rapidly adds mantle-derived material to earth’s
surface, releasing large amounts of unradiogenic Os and delivering it to the ocean. The
short residence time of Os in the oceans (~16 kyrs; Peucker-Ehrenbrink and Ravizza,
2000) means the whole-ocean
187
Os/
188
Os ratio quickly responds and is recorded in
marine sedimentary rocks. Os can therefore serve as a proxy for the initiation of CAMP
magmatism. And, as atmospheric CO
2
increases in association with CAMP,
187
Os/
188
Os
should rapidly respond and record a more radiogenic, weathering-derived signal,
signaling the feedback of weathering as the Earth System responds to CO
2
perturbation.
In comparison to C isotopes and Hg concentrations and isotopes and within a section with
robust absolute chronology, the Levanto section offered a fantastic test case for
comparing C cycle perturbations and two proxies for LIP volcanism in the marine
248
sedimentary record within a chronological framework and allowed us to compare these to
CAMP age dates.

B.2. PREVIOUS OSMIUM WORK ACROSS THE TJB
We assumed the Levanto section would be ideal for measuring osmium isotopes,
because
187
Os/
188
Os can be measured in organic-rich rocks, since hydrogeneous Os
dominates in organic rich rocks like those found at Levanto (e.g. Ravizza and Turekian
1992).
187
Os/
188
Os has been measured at two Triassic-Jurassic localities: St. Audrie’s Bay
(Cohen & Coe, 2007) and Japan (Kuroda et al., 2010) record a progression towards
unradiogenic
187
Os/
188
Os during the Rhaetian, with an initiation of radiogenic input near
the TJB. More specifically, in Japan, from a Norian
187
Os/
188
Os ratio of ~0.6, Rhaetian
187
Os/
188
Os decreases to a minimum of ~0.2, reflecting the input of unradiogenic values
through the Rhaetian until a sharp increase in the late Rhaetian (~0.52) followed by a
stable phase in the Hettangian (Kuroda et al., 2010). This suggests CAMP input began in
the early Rhaetian, and in the late Rhaetian increased CO
2
resulted in a shift towards
radiogenic values via continental weathering, until a new steady state was reached; these
data are supported by results at St. Audrie’s Bay. Although this provides a record of
CAMP input and subsequent weathering, these records lack well-constrained timing and
the TJB (specifically the first occurrence of P. spelae), and are therefore difficult to relate
to other datasets from the TJB.

249
B.3. PRELIMINARY OSMIUM ISOTOPES FROM THE LEVANTO SECTION
We measured six preliminary samples from Levanto (Fig 1; appendix B dataset)
spanning much of the section. We report these data with other relevant data, and with a
gray bar indicating the expected range of osmium initial values. Osmium initial values
are as high as 3, much higher than seawater or the other Triassic-Jurassic Boundary
sections, and as low as -2.57, which suggests disruption to the Re-Os system. Exremetly
radiogenic samples (LV38, LV55, LV88, LV121) imply a highly restricted basin that had
radiogenic material (e.g. black shales or ore deposits) weathering into it during
deposition. Since reasonable values (with respect to age; Fig 2) were obtained for two
samples (LV55 and LV88), and since the high Os values are from the portion of the
section with changing δ
15
N and trace metals, one interpretation of these data was that the
osmium initial values (see dataset) reflected an exceptionally restricted basin, with a
potential decrease in restriction during the Hettangian. We were also concerned that
weathering might have affected initial osmium isotope values because osmium is well
known to respond to surficial weathering on outcrops (e.g. Georgiev et al. 2012). We
drilled a core into the outcrop (discussed further in Appendix D) to test for the affect of
weathering on osmium and other proxies used in this thesis and measured both ends of
the core for osmium isotopes. We found more anomalous values from the relatively
unweathered portion of the core (-1.74; LVDR7D) compared to the more weathered
portion of the core (3.55; LVDR7A), which suggests neither basin restriction nor
weathering is conclusively the reason for the anomalous osmium isotope values measured
in other samples at the Levanto section.
250
200.5 201 201.5 202 202.5 203 203.5 204
2
4
6
8
10
δ
15
N
200.5 201 201.5 202 202.5 203 203.5 204
-30
-29
-28 δ
13
Corg
200.5 201 201.5 202 202.5 203 203.5 204
0
10
20
U (ppm)
200.5 201 201.5 202 202.5 203 203.5 204
0
500
V (ppm)
200.5 201 201.5 202 202.5 203 203.5 204
0
50
Mo (ppm)
200.5 201 201.5 202 202.5 203 203.5 204
0
4 %TOC
201 202 203 204
0
200
Re (ppm)
Triassic
Rhaetian Hettangian
Jurassic
ETE
-1
1
2
3
-2
-3
0
Osi
core from here
Figure 1. Levanto section data plotted against time, with initial osmium isotope values plotted with
organic carbon isotopes. Filled circles in other data sets refer to the same samples as the Osi mea-
surements, and are displayed to compare e.g. trace metal concentrations to Osi values. Expected
range of Osi (based on modern ocean and other TJB studies) is represented by the gray horizontal
bar. Osmium initial values are extremely radiogenic and may suggest radiogenic material was weath-
ering into the basin during deposition of the Levanto samples. We thought this could be due to basin
restriction or weathering, and we measured a core that should span this boundary but found anoma-
lous values from the supposedly unweathered portion.
251
Figure 2. Osmium values do plot on a ~200 Ma isochron which suggests their values may be
meaningful.
RO807-3_LV55
RO807-4_LV88
3.3
3.5
3.7
3.9
120 160 200 240 280 320
187
Re/
188
Os
187
Os/
188
Os
Age = 203±14 Ma
Initial
187
Os/
188
Os =2.874 ± 0.059
MSWD = 0.000
data-point error ellipses are 2
252
Additional ideas about what could have impacted the osmium system at Levanto
include potential disturbance during fluid migration, potential impact from ash beds
(although this should be unradiogenic and thus unlikely; also ash beds have not been
known to disturb the Re/Os system in previous studies), possible remobilization in pore
water during diagenesis. Additionally, in a hydrocarbon bearing system, observations
have been made that the Re and Os system can be substantially disturbed by groundwater
dissolution and remobilization of Os and organic matter trapped Re (Stein and Hannah
2014); something similar may have happened here. We may be able to test for potential
early diagenesis or fluid flow alteration by conducting a high resolution study along a
small portion of the outcrop or along one bed. We 15 samples spanning 1.5 meters in
three instances from the Levanto section, and these may help elucidate potential
mobilization of the Re Os system. Additionally, conducting cm-scale analyses may help
distinguish between early diagenetic mobilization of Re and Os and groundwater
alteration (because cm scale analyses could be done bed by bed). If osmium initial values
are due to extreme basin restriction changes, Nd isotopes may also help to distinguish
between alteration of the Re-Os system and changes in basin restriction.
Stein and Hannah (2014) observe that in a hydrocarbon bearing system, Re and
Os can be particularly high, with “Os and especially Re enriched in organic matter
relative to pyrite”. In the Levanto section, S has not been measured, but obvious pyrite
was notably absent from all thin sections. The missing pyrite from the section may also
be a clue to the disruption in the Re-Os system.
All osmium isotope analyses were made at Durham University by Dave Selby and
his lab. Josh West, Dave Selby and I interpreted the results. The osmium initial values are
253
so anomalous in this study that we may try and publish the results at a later date, pending
further investigation as to why the osmium system in this section is so disturbed.

254
REFERENCES
Cohen, A. S. and Coe, A. L. 2007. The impact of the Central Atlantic Magmatic Province on
climate and on the Sr- and Os-isotope evolution of seawater. P3 244, 374-390.
Georgiev, S., Stein, H.J., Hannah, J.L., Weiss, H.M., Bingen, B., Xu, G., Rein, E., Hatlø, V.,
Løseth, H., Nali, M., Piasecki, S., 2012. Chemical singals for oxidative weathering predict
Re-Os isochroneity in black shales, East Greenland. Chem. Geol., 324-325, 108-121.
Kuroda, J., Hori, R. S., Suzuki, K., Grocke, D. R., Ohkouchi, N. (2010) Marine osmium isotope
record across the Triassic-Jurassic boundary from a Pacific pelagic site. Geology 38, 1095-
1098.
Peucker-Ehrenbrink, B., Ravizza, G., 2000. The marine osmium isotope record. Terra Nova 12,
205-219.
Ravizza, G., Turekian, K. K., 1993. A possible link between the sea water osmium isotope record
and weathering of ancient sedimentary organic matter. Chem. Geol. 107, 255-258.
Shirey, S. B., and Walker, R. J., 1998. The Re–Os isotope system in cosmochemistry and high-
temperature geochemistry. Annual Review of Earth and Planetary Sciences, 26, 423–500.

255
B.4. OSMIUM ISOTOPE DATASET
Sample Re (ppb) ± Os (ppt) ± 192Os (ppt) ± 187Re/188Os ± 187Os/188Os ± rho Osi ±
200
LV11 155.81 0.38 748.00 3.03 268.25 0.94 1155.54 4.94 1.2864 0.0064 0.574 -2.57 0.02
LV38 43.08 0.11 621.19 3.48 183.12 0.68 467.97 2.08 3.1974 0.0167 0.585 1.64 0.02
LV55 19.03 0.05 468.19 2.86 129.96 0.51 291.27 1.36 3.8632 0.0214 0.593 2.89 0.03
LV88 14.64 0.04 608.37 4.23 175.41 0.93 166.06 1.00 3.4380 0.0257 0.618 2.88 0.03
LV121 29.54 0.07 523.52 3.11 145.64 0.54 403.51 1.81 3.8380 0.0202 0.591 2.49 0.03
LV145 31.37 0.08 428.12 1.47 163.69 0.61 381.19 1.71 0.7385 0.0039 0.588 -0.53 0.01
LVDR7A 3.54 0.01 257.63 1.95 71.42 0.40 98.65 0.60 3.8774 0.0316 0.620 3.55 0.03
LVDR7D 104.54 0.26 426.31 2.56 113.05 0.40 1839.75 7.91 4.3969 0.0221 0.578 -1.74 0.03
256
Appendix C. Rock eval data from ten Levanto samples

Programmed pyrolysis (aka Rock-eval) is a common method of assessing organic
matter type in the petroleum industry and for paleoevnironmental applications (reviewed
in Hart and Steen 2015). We measured ten samples from the Levanto section for rock
eval with GeoMark in an effort to understand the thermal maturity of the organic matter.
Data is reported in this appendix, but overall Levanto samples may be appropriate for
organic geochemistry due to their lack of thermal maturity.
257
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262
Pseudo Van Krevelen Plot
0
100
200
300
400
500
600
700
800
900
1000
0 20 40 60 80 100 120 140 160 180 200
Hydrogen Index (mg HC / g TOC)
Oxygen Index (mg CO2 / g TOC)
TYPE I KEROGEN!
TYPE II KEROGEN!
TYPE III KEROGEN!
TYPE IV KEROGEN!
263
Rock Leco Rock-Eval-2 Rock-Eval-2 Rock-Eval-2 Rock-Eval-2 Calculated Hydrogen Oxygen S2/S3 S1/TOC Production Experimental
ID TOC S1 S2 S3 Tmax %Ro Index Index Conc. Norm. Oil Index Notations
(wt%) (mg HC/g) (mg HC/g) (mg CO2/g) (°C) (RE TMAX) (S2x100/TOC) (S3x100/TOC)(mg HC/mg CO2) Content (S1/(S1+S2)
LV11 1.96 0.56 3.90 0.58 437 0.71 199 30 7 29 0.13 Low Temp S2 Shoulder
LV38 1.76 0.32 2.45 0.87 438 0.72 139 49 3 18 0.12
LV55 1.88 0.27 2.74 0.90 440 0.76 146 48 3 14 0.09
LV88 2.23 0.25 3.58 1.17 438 0.72 161 52 3 11 0.07
LV108 3.07 0.35 3.73 1.36 439 0.74 121 44 3 11 0.09
LV121 2.50 0.32 3.63 1.21 438 0.72 145 48 3 13 0.08
LV130 3.11 1.15 8.13 0.82 436 0.69 261 26 10 37 0.12 Low Temp S2 Shoulder
LV145 1.68 0.27 2.57 0.84 438 0.72 153 50 3 16 0.10
LV162 2.03 0.61 4.18 0.77 438 0.72 206 38 5 30 0.13 Low Temp S2 Shoulder
LV221 0.88 0.10 0.70 0.66 440 0.76 80 75 1 11 0.13
264
Appendix D: Outcrop weathering and sedimentary
geochemistry

All Triassic-Jurassic boundary sections (and any time period where outcrop rock
is being used) are either from surface outcrops or from drilled continental cores, since
drilling does not target sediments this old. Surficial weathering is obvious in outcrop at
the Levanto section (and indeed most stratigraphic sections). Although the weathering
community is well aware of this, little attention is paid to the affect of weathering on
outcrop studies of sedimentary geochemistry in deep time and so the Levanto weathering
test offers an opportunity to investigate weathering from a context of the potential effects
on geochemical proxies in a paleoecological context.
Josh West and I discussed making this test and Frank Corsetti and I drilled the
core. I ran the trace element samples and Dave Selby ran the osmium isotopes.
In figure 1 I display a photo of core LVDR7, which was drilled along a bedding
plane. We interpret the darker portion of the core (position D), which came from deeper
within the outcrop, as indicative of less weathering relative to the outer portion of the
core (position A). Each trace metal shows different mobilization to weathering. U, Cu,
Mn, V, Pb show little change based on this weather transect, while Mo and Zn show
substantial systematic enrichment when weathered. Re is substantially depleted along a
weathering transect. Co, Cd, Mn, Ni, are somewhat enriched along a weathering transect.
This must impact trace metal results to some extent from the Levanto section. However,
for the bulk of our interpretations in Chapter 3 (which involve V and U), this should not
265
be the primary signal observed. Mo enrichment could be part of the reason we observe
high Mo during the interval spanning ~200.8 to ~200 Ma, but it’s unlikely that the high
Mo observed near the ETE is also due to intense weathering because this is the only
interval elevated in Re, which suggest it may be less weathered than other portions of the
section.
δ
13
C
org
analyses on each portion of the core are -28.44‰ (LVDR7A), -28.43‰
(LVDR7B), -28.48‰ (LVDR7C), and -28.4‰ (LVDR7D), or well within analytical
uncertainty. We therefore conclude δ
13
C
org
curve is not primarily due to weathering of the
outcrop.
Finally, osmium initial values unweathered portion of the core suggests major
disruption to the Re-Os system, suggesting disturbance to the osmium system is not
simply due to weathering but was prior to weathering (e.g. see Appendix B).

266
Figure 1. Core LVDR7A (from approximately meter 60) from the Levanto section. This core was drilled
along a bedding plane in an effort to capture the effects of surficial weathering on proxies studied in this
thesis. Portion ‘D’ of the core in interpreted as less weathered and portion ‘A’ of the core is interpreted as
most weathered. Trace metal concentrations exhibit different patterns of mobilization, with some enriched
during weathering and some depleted. Osmium appears disturbed both in the unweathered and weathered
portions of the core, suggesting weathering is not the primary cause of anomalous Osi values. All sections of
cores had a δ
13
C
org
value of -24.4‰, suggesting weathering did not affect δ
13
C
org
analyses at the Levanto
section.
267
Co
A
B
C
D
A
B
C
D
A
B
C
D
Re
Pb
Cd
0 50 100 150 200 250 300 350 400
Mn
Ni
V
Zn
0 10 20 30 40 50
U
Cr
Mo
Cu
0 5 10 15
Assumed less weathered
Osi = -1.74
Osi = 3.55
Assumed more weathered
268
Appendix E: SEM/EDS imaging of a sample from the
Levanto section highlight the presence of P

E.1. EDS AND SEM MAPPING
As discussed in this thesis (e.g. Chapter 1 and Appendix A), in sedimentary
geochemistry paying attention to the depositional setting and diagenetic environment is
vital to interpreting geochemical data. Each proxy is different, and so this assessment
must be made on a proxy by proxy and sample by sample basis. In addition to the sample
specific differences discussed, there are also microenvironments within samples during
deposition, diagenesis, and lithificaiton that for the most part in this thesis were largely
ignored. We utilized bulk sample geochemistry in chapters 2-4, which homogenizes a
rock. However, high-resolution assessment of samples, especially those exhibiting
stratified layers (e.g. LV78), may yield additional information about geochemistry.
Following an SEM/EDS mapping campaign on the samples from Kennecott Point, Haida
Gwaii, Canada in collaboration with Ken Williford and Michael Tuite at JPL, I made a
high resolution, whole thin section map from Levanto (Fig 1). LV78 is unique amongst
the samples from Levanto in that it hosts many spicules in the center of the sample and is
interpreted as an event bed (in general single beds were rare in thin section and outcrop).
This is particularly useful in understanding some of the preservational differences in part
of the sample. For example, in the ‘event’ bed with many spicules, we see much more
carbonate. Further up and down the sample, there are horizons with much higher P
concentrations. This highlights several questions for this particular sample: does the high
269
%CARB bed preserve the spicules, or did the presence of spicules buffer the dissolution
of carbonate? Did P migrate into discrete layers based on micro-enivronments in oxygen
concentrations within the sediment, or were other elements winnowed out or
remobilized? An additional question generated from this section (and the general
observation of no obvious pyrite from the Levanto section) is little to no S is observed in
this elemental map. Finally, this map highlights the presence of P, which would also be
great to measure in the future. Could the presence of P signal the removal of N during
denitrification without corresponding removal of P?

270
Figure 1. Elemental map for sample LV78. Each element layer is given a color and is underlain by
elements to the right of it in the key. For example, P is the top layer. Ca-rich layer in center of the section
hosts many spicules (which were analyzed in chapter 5).
271
Appendix F. Hg and S are associated in a sample from
Kennecott Point

I made elemental maps using scanning electron microscopy (SEM) and energy
dispersive spectrometry (EDS) from about 65 samples from Kennecott Point (Haida
Gwaii, Canada; Williford et al., 2007) with Ken Williford and Michael Tuite at JPL.
These are similar to the map found in Fig 1 (for KPF16). I also measured Hg at high
resolution in these samples using EDS to investigate where Hg occurs within a
sedimentary rock. In Fig 2, a high resolution EDS map demonstrates a strong association
between S and Hg in this sample, which suggests normalizing Hg to TOC (e.g. chapter 5)
may not completely correct Hg concentrations for changes in depositional settings and
Hg association loading. Hg may be associated with S (e.g. Fitzgerald et al., 2007) and in
other mass extinction intervals the associations between Hg and S has been inferred to be
environmental (e.g. Grasby et al., 2013). In figure 3 Hg is associated with S and to some
extent C; however in Fig 4 Hg and S are associated with no C present. Early pore water
diagenesis leads to associations between organic matter and S, and so the association
between Hg and S seen here may indicate early mobilization of S and drawdown of Hg
within the pore water. This does not preclude the association of organic matter and Hg,
but may suggest S is an additional measurement to be compared to all Hg concentrations
in sedimentary rocks, and may help further clarify the Hg proxy. Furthermore, Hg and S
both are both released from volcanoes, and so it is also possible that increased Hg
concentrations seen during LIP intervals may be associated with high S in the Earth and
272
ocean systems and in the sedimentary record. More work is needed to fully understand
the association between Hg, S, and organic matter within the sedimentary record and in
context to LIP and CAMP magmatism.

273
Figure 1. Photomosaic for KPF16 (left) and corresponding elemental map (right). High-resolu-
tion EDS map was generated for the white box (see Fig 2).
Fig 2
274
Figure 2. Hg-focused high resolution elemental map for sample KPF16. Left: Hg is the top
layer; right: S is the top layer. If you zoom in you can see that Hg overlays S in every case
and is associated with framboid pyrite.
1 mm 1 mm
Fig 3
Fig 4
Fig 3
Fig 4
275
Figure 4. Enlarged view of white rectangle in Fig 2. Here, C is not associated with Hg
and S in this portion of the sample.
Figure 3. Enlarged view of white rectangle in Fig 2. Here, Hg and S are co-located and in
some cases are located close to C.
1 mm
1 mm
276
REFERENCES
Fitzgerald, W.F., Lamborg, C. H., Hammerschmidt, C.R., 2007. Marine Biogeochemical Cycling
of Mercury, Chem. Rev., 107, 641-662.
Grasby, S.E., Sanei, H., Beauchamp, B., and Chen, Z., 2013, Mercury deposi- tion through the
Permo-Triassic Biotic Crisis: Chemical Geology, v. 351, p. 209–816,
doi:10.1016/j.chemgeo.2013.05.022.
Williford, K. H., Ward, P. D., Garrison, G. H., Buick, R., 2007. An extended organic carbon-
isotope record across the Triassic-Jurassic boundary in the Queen Charolette Islands, British
Columbia, Canada. Palaeogeogr. Palaeoclimatol.Palaeoecol. 244, 290-296, doi:
10.1016/j.palaeo.2006.06.032.

277
Appendix G. C isotope and concentration data from Levanto, Peru (datset from Chapter 2)
Meter Sample Age %TOC %TOC 1s %SD δ13Corg δ13Corg 1s Replicates %TIC %TIC 1s % SD δ13Ccarb δ13Ccarb 1s Replicates %CARB
0 LV1 204.16 1.29 0.12 3.15 -30.00 0.03 2 7.36 0.01 0.18 1.81 0.01 2 61
0.6 LV2 204.13 1.54 0.06 1.00 -30.38 0.01 2 7.85 -0.95 1 65
1 LV3 204.12 0.99 -30.24 1 6.02 -0.73 1 50
1.5 LV4 204.10 1.43 -30.03 1 5.79 -1.34 1 48
2 LV5 204.08 0.49 -30.14 1 8.77 0.05 0.58 -2.71 0.08 2 73
2.15 LV7 204.07 0.98 0.03 0.97 -30.14 0.03 2 7.01 -1.35 1 58
3 LV8 204.04 1.61 0.02 0.76 -30.41 0.02 2 4.88 -1.92 1 41
3.6 LV10 204.02 1.17 -29.89 1 6.32 0.02 0.25 0.38 0.13 3 53
4 LV11 204.00 1.96 -30.05 1 7.80 0.05 0.69 -1.14 0.03 5 65
4.5 LV12 203.98 0.75 0.00 0.04 -29.78 0.01 2 7.33 0.01 0.08 -1.75 0.01 2 61
5 LV13 203.96 0.53 -30.05 1 7.25 -1.22 1 60
5.5 LV14 203.94 0.56 0.00 0.09 -29.86 0.01 2 5.82 -1.79 1 48
6 LV15 203.93 1.03 -30.11 1 6.69 0.05 0.68 0.40 0.22 2 56
6.5 LV16 203.91 1.19 -30.10 1 9.65 0.06 0.58 1.15 0.04 2 80
7 LV17 203.89 1.40 0.01 0.62 -30.08 0.02 2 3.26 0.02 0.48 -0.94 0.06 2 27
7.5 LV19 203.87 0.66 -29.86 1 7.38 -2.40 1 62
8 LV20 203.85 0.84 0.01 0.42 -29.98 0.02 2 4.02 -1.55 1 33
8.5 LV21 203.83 1.89 -30.05 1 7.29 -1.91 1 61
9.05 LV22 203.81 0.93 0.02 0.62 -30.01 0.03 4 7.13 0.02 0.22 -1.66 0.01 2 59
9.5 LV23 203.79 0.95 0.00 0.16 -30.07 0.00 2 5.83 -1.66 1 49
10 LV24 203.77 1.83 -29.94 1 6.77 0.05 0.67 -1.73 0.06 2 56
10.6 LV25 203.75 1.86 0.01 0.16 -30.04 0.03 3 6.61 0.01 0.10 -2.30 0.03 2 55
11.1 LV26 203.73 2.41 -30.14 1 6.18 0.01 0.09 -1.55 0.02 2 52
11.6 LV27 203.71 1.79 -30.19 1 5.24 -1.44 1 44
12 LV28 203.68 2.56 0.02 0.22 -30.04 0.03 2 7.45 -1.34 1 62
12.6 LV29 203.62 1.85 -29.81 1 2.93 0.04 1.34 0.09 0.01 2 24
13 LV30 203.59 2.47 0.01 0.18 -29.90 0.02 2 5.58 0.02 0.41 -1.70 0.02 2 47
13.55 LV31 203.54 2.02 -30.18 1 5.79 -1.22 1 48
13.67 LV32 203.53 2.32 -29.94 1 8.19 -0.98 1 68
14.5 LV34 203.46 2.09 0.03 0.43 -29.98 0.05 2 7.19 -0.80 1 60
15.1 LV35 203.41 2.12 -30.12 1 6.95 -1.31 1 58
15.5 LV36 203.38 2.44 0.03 0.31 -29.82 0.01 2 7.88 0.02 0.22 -0.97 0.00 2 66
16 LV37 203.33 2.06 -30.04 1 6.41 -0.59 1 53
16.5 LV38 203.29 1.76 -29.88 1 8.26 -0.67 1 69
17 LV39 203.25 1.90 0.01 0.17 -29.92 0.01 2 5.44 -0.91 1 45
17.5 LV40 203.20 1.51 -29.65 1 6.23 -0.36 1 52
18 LV41 203.16 1.23 0.23 6.41 -30.10 0.05 2 7.12 0.02 0.29 -1.67 0.00 2 59
18.5 LV42 203.12 3.19 -30.11 1 3.28 -0.57 1 27
19 LV43 203.08 2.09 -30.25 1 7.31 -1.18 1 61
19.5 LV44 203.03 3.92 0.00 0.02 -30.13 0.04 2 2.45 -0.20 1 20
20 LV45 202.99 2.06 -29.92 1 7.43 0.07 0.93 -0.43 0.04 2 62
20.45 LV46 202.95 2.16 0.00 0.03 -29.73 0.01 2 7.92 0.01 0.12 -0.87 0.01 2 66
21 LV47 202.90 1.46 -29.88 1 7.07 0.00 0.05 -0.85 0.01 2 59
21.5 LV48 202.86 1.72 -29.50 1 8.35 -0.66 1 70
21.9 LV49 202.83 2.09 0.03 0.51 -29.86 0.09 2 6.28 -0.76 1 52
22.5 LV50 202.77 0.33 0.00 0.19 -29.57 0.08 2 6.08 -0.65 1 51
23 LV51 202.73 1.46 -30.05 1 6.17 -0.80 1 51
23.5 LV52 202.69 2.52 -30.26 1 5.86 0.02 0.40 -0.84 0.08 2 49
24 LV53 202.65 1.75 -30.17 1 7.74 -1.11 1 65
24.5 LV54 202.60 4.09 0.01 0.10 -30.10 0.01 2 2.68 0.01 0.47 -0.31 0.03 3 22
25 LV55 202.56 1.88 -29.83 1 7.73 -0.59 1 64
25.52 LV56 202.52 1.69 0.08 0.83 -29.63 0.02 2 9.51 -1.28 1 79
26 LV57 202.47 2.48 -29.85 1 7.19 0.02 0.25 -0.33 0.02 2 60
26.45 LV58 202.44 2.86 -29.79 1 7.86 -0.97 1 65
27.1 LV59 202.38 1.84 0.01 0.20 -29.92 0.26 2 7.20 0.08 1.12 -0.58 0.01 2 60
27.55 LV60 202.36 2.89 0.03 0.36 -30.19 0.04 2 6.61 0.01 0.10 -0.73 0.04 2 55
28 LV61 202.35 2.42 0.03 0.58 -30.21 0.01 2 6.25 -0.59 1 52
28.5 LV62 202.33 0.95 0.00 0.12 -30.27 0.06 2 1.06 0.01 1.19 -0.23 0.05 39
28.95 LV63 202.31 1.03 0.02 1.57 -30.42 0.07 2 2.47 0.02 0.71 0.29 0.04 4 21
29.45 LV64 202.29 2.56 -29.95 1 6.61 -0.08 1 55
30 LV65 202.27 1.39 -30.32 1 5.33 0.09 1 44
30.6 LV66 202.25 2.11 0.03 0.53 -29.95 0.04 2 6.46 0.07 1 54
31 LV67 202.23 1.91 0.01 0.16 -29.99 0.04 2 7.51 0.05 0.65 -0.52 0.04 2 63
31.55 LV68 202.21 0.83 -30.17 1 1.16 0.00 0.29 1.42 0.01 3 10
278
Meter Sample Age %TOC %TOC 1s %SD δ13Corg δ13Corg 1s Replicates %TIC %TIC 1s % SD δ13Ccarb δ13Ccarb 1s Replicates %CARB
32 LV69 202.20 2.45 -29.97 1 6.76 -0.33 1 56
32.5 LV70 202.18 0.71 -29.91 1 5.49 0.01 0.20 -0.02 0.09 2 46
33 LV71 202.16 3.57 -29.58 1 3.19 0.02 0.48 -0.18 0.01 2 27
33.43 LV72 202.15 2.15 0.05 1.00 -29.59 0.03 2 5.58 0.07 1.31 -0.30 0.03 2 47
34 LV73 202.14 2.01 -29.64 1 6.86 0.18 1 57
34.5 LV74 202.13 2.02 -29.59 1 7.36 -0.34 1 61
35 LV75 202.12 2.33 -29.16 1 7.58 0.03 1 63
35.5 LV76 202.11 1.90 -28.29 1 10.30 0.12 1 86
36 LV77 202.10 2.98 -28.74 1 7.07 0.08 1.15 -0.41 0.06 2 59
36.4 LV78 202.09 3.15 -29.74 1 3.75 0.03 0.88 -0.84 0.12 3 31
37 LV79 202.08 1.64 -29.95 1 8.53 0.05 0.59 -0.65 0.04 2 71
37.5 LV80 202.07 2.42 -29.82 1 7.16 0.01 0.15 -0.14 0.01 2 60
38 LV81 202.06 2.79 -29.72 1 7.22 -0.51 1 60
38.1 LV83 202.05 1.92 -29.43 1 7.99 0.02 0.28 -0.08 0.03 2 67
38.45 LV84 202.06 2.57 0.04 -29.34 0.06 1 5.90 -0.35 1 49
38.45 LV82 202.05 2.44 0.80 -29.47 2 5.31 0.13 1 44
39 LV85 202.04 0.41 -29.36 1 6.48 0.39 1 54
39.6 LV86 202.03 2.38 -29.26 1 5.42 0.02 0.44 0.09 0.06 2 45
40 LV87 202.02 1.34 1.73 30.82 -29.34 0.17 2 6.71 -0.74 1 56
40.5 LV88 202.02 2.23 -29.41 1 7.81 0.13 1 65
41 LV89 202.01 2.43 -29.20 1 8.39 0.06 1 70
41.3 LV90 202.00 2.14 -29.30 1 5.83 0.02 0.33 -0.62 0.15 2 49
41.5 LV91 202.00 0.81 -29.65 1 6.45 0.06 0.96 -0.76 0.05 3 54
42 LV92 201.99 0.87 -29.86 1 1.24 0.01 0.54 1.71 0.09 4 10
42.5 LV93 201.98 0.50 0.02 1.65 -30.16 0.00 3 6.19 0.04 0.57 -0.61 0.05 2 52
43 LV94 201.97 0.56 0.01 0.87 -29.86 0.04 3 5.66 0.09 1.52 0.03 0.06 2 47
43.5 LV95 201.96 2.74 0.17 2.47 -30.16 0.18 2 6.20 -0.41 1 52
44 LV96 201.95 3.75 -29.48 1 5.93 0.01 0.17 -0.31 0.03 2 49
44.65 LV97 201.93 2.19 -29.77 1 6.70 0.05 1 56
45 LV98 201.93 1.57 0.04 0.75 -29.71 0.19 2 7.61 -0.66 1 63
45.5 LV99 201.92 2.37 0.64 7.19 -29.60 0.32 3 8.30 0.14 1 69
46 LV100 201.91 1.45 0.17 5.88 -29.72 0.17 2 5.08 -0.07 1 42
46.5 LV101 201.90 3.20 -29.67 1 6.68 0.10 1.45 0.10 0.01 3 56
47 LV102 201.89 2.72 -29.73 1 6.07 -0.03 1 51
47.5 LV103 201.88 2.15 -29.82 1 7.11 0.01 1 59
48 LV104 201.87 1.76 0.07 1.34 -29.94 0.03 3 7.51 -0.03 1 63
48.5 LV105 201.85 2.61 -29.80 1 6.94 0.01 1 58
49.05 LV106 201.82 2.79 0.36 4.40 -29.32 0.07 3 7.53 0.14 1.86 0.36 0.16 4 63
49.5 LV107 201.80 1.36 0.21 6.20 -29.00 0.05 6 6.54 0.32 1 54
50 LV108 201.78 3.07 0.06 0.70 -29.37 0.08 3 7.31 0.47 1 61
50.5 LV109 201.76 0.70 -29.15 1 8.75 -0.32 1 73
51.05 LV110 201.73 1.97 0.36 4.37 -28.99 0.10 6 8.84 0.08 1 74
51.55 LV111 201.71 3.74 0.02 0.13 -27.93 0.04 3 9.23 0.17 1.90 0.59 0.08 4 77
52 LV112 201.69 4.50 -28.04 1 7.78 0.13 1.66 0.57 0.05 5 65
52.5 LV113 201.67 3.80 0.96 10.84 -28.32 0.06 3 6.30 0.00 0.01 0.81 0.09 2 52
53 LV114 201.65 2.51 0.05 0.42 -28.27 0.05 2 8.87 0.47 1 74
53.5 LV115 201.62 2.54 -27.70 1 8.50 0.37 1 71
54 LV116 201.60 3.63 -27.97 1 8.31 0.67 1 69
54.55 LV117 201.58 3.32 -27.96 1 7.21 0.77 1 60
54.85 LV118 201.56 1.03 -27.79 1 6.59 0.39 1 55
55.45 LV119 201.53 1.23 -28.44 1 8.46 0.34 1 71
56 LV120 201.51 1.26 -28.74 1 9.04 0.03 0.33 -0.71 0.11 2 75
56.5 LV121 201.50 2.50 -28.66 1 9.16 0.62 1 76
57.1 LV122 201.49 0.85 0.21 11.86 -29.07 0.10 4 5.06 0.01 1 42
57.5 LV123 201.48 1.74 -29.29 1 5.96 0.40 1 50
58 LV124 201.47 2.30 -29.19 1 8.01 0.05 0.56 4.99 0.12 5 67
58.5 LV125 201.46 1.74 -29.09 1 7.55 0.93 1 63
59 LV126 201.44 1.17 -28.97 1 8.92 -0.01 1 74
59.15 LV127 201.44 0.73 -28.66 1 2.88 0.02 0.63 0.78 0.05 2 24
60 LV128 201.42 1.49 -28.91 1 8.58 0.04 0.47 3.17 0.01 2 72
60.5 LV129 201.41 3.72 0.02 0.42 -28.93 0.01 2 3.18 0.01 0.33 0.48 0.01 3 27
61 LV130 201.40 3.11 -28.98 1 4.00 0.01 0.23 0.88 0.05 3 33
61.5 LV131 201.39 0.51 0.03 3.54 -28.79 0.11 2 4.75 0.91 1 40
62 LV132 201.38 0.95 -28.81 1 8.04 0.47 5.81 4.22 0.06 3 67
62.5 LV133 201.36 1.43 -28.87 1 6.31 0.05 0.82 -0.22 0.10 2 53
63 LV134 201.35 3.37 -28.96 1 6.37 0.03 0.48 0.88 0.05 5 53
279
Meter Sample Age %TOC %TOC 1s %SD δ13Corg δ13Corg 1s Replicates %TIC %TIC 1s % SD δ13Ccarb δ13Ccarb 1s Replicates %CARB
63.45 LV135 201.34 0.85 0.02 1.41 -28.66 0.07 2 1.89 0.02 1.17 0.85 0.09 2 16
64 LV136 201.32 0.48 -28.40 1 3.16 0.02 0.60 0.61 0.06 3 26
64.5 LV137 201.29 1.59 -28.42 1 7.58 0.06 0.74 3.17 0.07 2 63
65.05 LV138 201.25 1.65 0.04 0.51 -28.46 0.06 3 9.16 0.07 0.80 2.25 0.03 3 76
65.5 LV139 201.22 0.66 0.10 8.05 -28.28 0.05 4 4.96 0.02 0.35 2.26 0.02 2 41
66 LV140 201.18 0.60 0.01 1.31 -28.36 0.03 2 4.68 0.06 1.20 1.88 0.05 2 39
66.5 LV141 201.15 0.65 0.10 6.39 -28.40 0.04 3 6.24 0.63 1 52
67 LV142 201.12 0.85 0.05 2.91 -28.44 0.04 2 5.84 1.21 1 49
67.45 LV143 201.09 0.85 0.05 1.90 -28.53 0.04 4 7.48 1.41 1 62
68 LV144 201.05 0.66 0.02 0.98 -28.67 0.07 2 7.55 1.59 1 63
68.5 LV145 201.01 1.68 0.05 0.92 -28.69 0.02 2 7.75 1.64 1 65
69 LV146 200.98 0.56 0.01 1.03 -28.48 0.04 2 5.29 0.01 0.23 1.12 0.15 2 44
69.5 LV147 200.95 0.55 0.02 1.17 -28.66 0.01 2 7.40 1.83 1 62
70 LV148 200.91 0.57 0.02 1.28 -28.60 0.05 4 7.30 2.16 1 61
70.5 LV149 200.88 0.85 0.05 2.80 -28.71 0.05 2 5.32 0.95 1 44
70.8 LV150 200.86 0.55 0.02 1.40 -28.75 0.02 2 6.56 1.08 1 55
71.5 LV151 200.81 0.50 0.01 0.82 -28.92 0.01 2 6.26 0.06 0.93 1.70 0.05 4 52
72 LV153 200.77 1.50 0.09 0.97 -28.78 0.11 3 0.12 0.65 11
72.1 LV152 200.78 0.74 0.01 4.01 -28.75 0.07 2 0.10 0.00 0.81 -2.05 0.13 21
72.55 LV154 200.74 0.50 0.00 0.02 -29.19 0.02 2 7.85 1.12 1 65
73 LV155 200.73 0.50 0.00 0.07 -29.05 0.04 2 7.32 0.04 0.57 1.06 0.03 2 61
73.45 LV156 200.73 0.49 0.08 5.31 -28.92 0.05 4 7.29 0.66 1 61
74 LV157 200.72 1.03 0.02 1.10 -29.01 0.06 2 4.65 0.90 1 39
74.4 LV158 200.71 0.47 0.01 1.01 -28.86 0.06 2 6.48 0.99 1 54
74.9 LV159 200.71 1.37 0.02 0.29 -29.02 0.00 2 8.74 1.37 1 73
75.5 LV160 200.70 0.69 0.00 0.06 -28.98 0.02 2 3.76 0.98 1 31
76 LV161 200.69 0.63 -29.02 1 8.72 0.04 0.45 0.93 0.01 2 73
76.3 LV162 200.69 2.03 0.04 0.63 -29.28 0.05 2 7.88 0.36 1 66
76.5 LV163 200.69 0.49 -29.16 1 5.75 0.02 0.36 0.63 0.03 2 48
76.9 LV164 200.68 0.50 -29.07 1 6.38 0.09 1.46 0.34 0.04 2 53
77.5 LV165 200.67 1.66 0.01 0.11 -28.96 0.04 2 8.85 1.54 1 74
78.1 LV166 200.66 2.50 0.02 0.19 -28.92 0.01 2 8.27 0.20 1 69
78.5 LV167 200.66 0.56 0.12 6.36 -28.74 0.02 3 7.92 0.28 1 66
79 LV168 200.65 0.48 -28.99 1 6.48 0.03 0.44 0.18 0.02 2 54
79.5 LV169 200.65 0.60 -29.15 1 6.39 0.31 1 53
80 LV170 200.64 0.42 0.00 0.03 -29.15 0.02 2 7.64 0.58 1 64
80.5 LV171 200.63 1.39 -29.17 1 7.76 -0.81 1 65
81 LV172 200.63 0.40 -29.07 1 7.35 0.86 1 61
81.5 LV173 200.62 0.60 0.02 0.66 -29.27 0.04 3 8.76 1.80 1 73
82 LV174 200.61 0.66 -29.02 1 1.67 0.01 0.48 -0.06 0.13 4 14
82.5 LV175 200.61 0.31 -29.19 1 6.99 0.48 1 58
82.5 LV176 200.61 0.56 -29.02 1 1.52 0.00 0.20 -0.31 0.13 2 13
83 LV177 200.60 0.56 0.02 1.64 -29.34 0.08 2 6.53 0.12 1 54
83 LV178A 200.60 0.50 -29.46 1 7.99 -0.32 1 67
83.25 LV178B 200.60 1.00 -29.39 1 8.47 0.03 0.40 1.03 0.01 2 71
83.5 LV179 200.59 0.37 -29.42 1 7.48 -0.14 1 62
84 LV180 200.59 0.88 0.01 0.28 -29.47 0.07 2 8.72 1.13 1 73
84.1 LV181 200.58 0.68 0.00 0.22 -29.11 0.01 2 2.26 0.01 0.45 0.03 0.00 2 19
84.5 LV182 200.58 0.43 0.72 69.25 -29.27 0.46 2 1.22 0.01 0.95 -0.75 0.05 3 10
85.2 LV183 200.57 0.91 -29.31 1 4.08 0.07 1.62 -0.83 0.18 2 34
85.5 LV184 200.56 0.52 -29.39 1 7.81 0.17 1 65
86 LV185 200.56 1.27 0.04 0.79 -29.74 0.08 2 8.34 0.53 1 70
86.5 LV186 200.55 0.72 -29.34 1 3.27 0.04 1.18 -0.64 0.11 3 27
87 LV187 200.54 0.37 0.01 0.84 -29.47 0.03 3 6.75 0.01 0.14 -0.12 0.01 2 56
87.5 LV188 200.54 0.50 0.01 1.53 -29.41 0.02 2 3.52 0.01 0.29 -0.97 0.06 4 29
88 LV189 200.53 0.56 0.01 0.60 -28.96 0.03 2 2.89 -0.84 1 24
88.25 LV190 200.53 0.43 0.05 1.15 -29.66 0.07 3 10.67 -3.94 1 89
88.5 LV191 200.52 0.41 0.01 0.85 -29.08 0.13 2 3.25 0.02 0.51 -1.15 0.17 3 27
89 LV192 200.52 0.44 0.04 4.57 -29.18 0.04 3 4.54 0.00 0.01 -1.00 0.01 2 38
89.5 LV193 200.51 0.38 0.00 0.55 -29.23 0.02 2 4.16 0.02 0.59 -1.13 0.06 2 35
90 LV194 200.50 0.30 0.00 0.21 -29.27 0.04 2 8.11 -0.56 1 68
90.5 LV195 200.50 0.52 0.02 3.05 -29.46 0.26 3 1.92 -0.76 1 16
91 LV196 200.49 0.51 0.03 2.44 -29.50 0.01 2 6.96 -0.35 1 58
91.5 LV197 200.48 0.37 0.01 2.13 -29.27 0.11 3 3.17 0.02 0.55 -2.43 0.17 3 26
92 LV198 200.48 0.58 -29.60 1 8.75 0.04 0.49 0.43 0.00 2 73
92.5 LV199 200.47 0.47 0.00 0.82 -29.37 0.10 3 0.95 0.00 0.42 -0.73 0.11 28
280
Meter Sample Age %TOC %TOC 1s %SD δ13Corg δ13Corg 1s Replicates %TIC %TIC 1s % SD δ13Ccarb δ13Ccarb 1s Replicates %CARB
93 LV200 200.46 0.36 -29.49 1 6.37 -0.81 1 53
93.3 LV201 200.46 0.50 -30.00 1 8.51 0.11 1 71
93.5 LV202 200.46 0.72 0.03 3.00 -29.64 0.03 2 2.72 -1.26 1 23
94 LV203 200.45 0.39 0.01 0.66 -29.85 0.06 2 8.09 0.01 0.09 0.14 0.12 2 67
94.5 LV204 200.44 0.41 0.01 1.43 -29.66 0.12 2 6.05 -1.14 1 50
95 LV205 200.42 0.99 0.05 3.16 -29.54 0.04 3 3.00 0.02 0.57 -1.27 0.00 2 25
95.5 LV206 200.41 0.37 0.00 0.24 -29.55 0.03 3 8.48 -0.20 1 71
96 LV207 200.39 0.51 0.04 5.74 -29.34 0.00 2 2.11 -1.20 1 18
96.5 LV208 200.38 0.59 0.01 0.64 -29.87 0.10 2 4.92 0.02 0.43 -2.26 0.02 2 41
96.9 LV209 200.36 0.47 0.04 2.64 -29.92 0.03 2 8.16 -0.13 1 68
97.5 LV210 200.35 0.23 0.00 0.55 -29.43 0.02 2 6.59 0.02 0.32 -2.31 0.14 2 55
98 LV211 200.33 0.21 0.01 1.35 -29.51 0.06 2 5.25 0.05 0.90 -2.16 0.11 2 44
98.5 LV212 200.32 0.26 0.01 1.24 -29.63 0.06 2 5.78 0.05 0.95 -2.32 0.09 2 48
99 LV213 200.30 0.16 0.01 1.35 -29.27 0.07 2 8.78 0.04 0.45 -1.16 0.04 2 73
99.5 LV214 200.29 0.43 0.01 0.76 -29.91 0.03 2 8.40 0.04 0.42 -0.72 0.02 2 70
100 LV215 200.27 0.29 0.00 0.38 -29.75 0.04 2 6.29 -2.65 1 52
100.5 LV216 200.26 0.61 -29.68 1 0.07 -2.12 11
100.9 LV217 200.25 0.66 -30.19 1 8.00 -0.87 1 67
101.5 LV218 200.23 0.56 0.00 0.42 -29.64 0.01 2 0.55 0.00 0.10 -0.96 0.06 25
102 LV219 200.22 0.70 0.21 8.77 -30.13 0.07 2 8.10 -1.06 1 68
102 LV220 200.22 0.48 -29.50 1 0.48 -0.42 14
102.5 LV221 200.20 0.88 0.33 14.57 -30.08 0.20 2 7.05 -2.08 1 59
103 LV222 200.19 0.55 -29.37 1 0.89 0.00 0.39 -0.79 0.02 27
103.5 LV223 200.17 0.50 0.57 53.61 -29.90 0.16 2 7.51 -0.87 1 63
104 LV224 200.16 0.45 -29.56 1 0.60 -1.76 15
104.5 LV225 200.14 0.79 0.01 0.30 -30.21 0.03 2 6.42 -2.72 1 54
105 LV226 200.13 0.47 -30.06 1 8.15 -2.49 1 68
105 LV227 200.13 0.43 0.00 0.68 -29.76 0.05 3 0.34 -0.54 13
281
Appendix H. Nitrogen isotope and trace metal concentration data (dataset from Chapter 3).
H.1. LEV ANTO, PERU
Meter Age Sample Cd (ppm) Pb (ppm) Mo (ppm) Re (ppm) U (ppm) Co (ppm) Cu (ppm) Cr (ppm) V (ppm) Mn (ppm) Ni (ppm) Zn (ppm) δ15N % N C:N %Detrital MARtoc MARcac03 MARdetrital
0 204.16 LV1 2.6 6.0 3.6 3.1 1.8 1.6 12 71 149 636 23 109 8.29 0.1 14 35.16 0.24 4.31 2.47
0.6 204.13 LV2 4.1 7.2 3.8 4.2 4.9 1.0 22 144 259 235 27 203 8.25 0.1 17 30.44 0.29 4.60 2.14
1 204.12 LV3 4.0 12.4 3.8 0.7 3.7 1.9 24 114 236 157 32 195 8.91 0.1 9 47.15 0.19 3.53 3.31
1.5 204.10 LV4 4.9 12.5 4.1 1.3 4.0 2.2 28 141 364 244 49 242 7.97 0.1 13 47.88 0.27 3.39 3.37
2 204.08 LV5 1.2 3.4 3.7 0.1 0.5 1.1 3 4 29 223 12 30 8.52 0.2 3 25.64 0.09 5.13 1.80
2.15 204.07 LV7 2.2 7.5 2.8 1.1 2.5 1.8 21 59 152 278 20 114 7.87 0.1 12 38.95 0.19 4.10 2.74
3 204.04 LV8 4.9 7.3 5.9 9.5 5.3 0.9 18 82 272 176 26 179 9.05 0.1 19 55.02 0.31 2.86 3.87
3.6 204.02 LV10 1.2 5.5 3.4 8.9 2.1 2.0 15 71 133 430 24 114 8.21 0.1 12 44.15 0.22 3.70 3.10
4 204.00 LV11 1.4 6.1 3.1 106.1 2.9 1.3 15 79 146 223 24 128 6.89 0.1 24 29.75 0.37 4.57 2.09
4.5 203.98 LV12 2.1 9.9 5.4 0.7 1.8 1.6 13 31 120 221 32 128 8.08 0.2 6 36.93 0.14 4.29 2.60
5 203.96 LV13 4.7 20.2 8.4 1.6 2.9 2.5 24 97 243 313 58 312 6.86 0.1 8 38.11 0.10 4.25 2.68
5.5 203.94 LV14 2.7 6.9 7.6 0.3 2.8 1.5 25 90 176 159 29 104 8.88 0.1 5 49.98 0.11 3.41 3.51
6 203.93 LV15 0.3 9.3 2.6 8.6 1.3 1.7 12 51 110 476 21 89 7.88 0.1 12 41.44 0.20 3.92 2.91
6.5 203.91 LV16 0.5 2.9 1.2 12.1 0.8 0.6 7 38 64 652 11 43 7.53 0.1 22 16.35 0.23 5.65 1.15
7 203.89 LV17 9.6 15.8 18.9 5.4 6.9 1.7 37 136 8.12 0.2 10 69.08 0.27 1.91 4.86
7.5 203.87 LV19 2.7 8.4 4.7 0.6 3.0 1.1 25 68 248 288 32 160 8.21 0.1 7 36.68 0.13 4.32 2.58
8 203.85 LV20 2.4 6.6 7.7 0.6 3.8 3.0 35 180 256 101 66 291 8.88 0.1 8 64.26 0.16 2.35 4.52
8.5 203.83 LV21 1.4 9.7 2.0 65.2 1.7 1.0 19 63 166 210 17 130 9.87 0.1 20 34.16 0.36 4.27 2.40
9.05 203.81 LV22 4.1 10.8 3.3 1.3 3.6 1.2 19 87 183 182 36 178 9.07 0.1 17 38.05 0.18 4.18 2.67
9.5 203.79 LV23 2.4 17.0 5.9 2.0 3.5 2.1 23 109 255 171 41 215 8.78 0.1 10 48.88 0.18 3.41 3.44
10 203.77 LV24 1.0 7.0 1.8 11.1 1.9 0.6 15 79 172 144 19 125 9.80 0.1 26 38.63 0.35 3.97 2.72
10.6 203.75 LV25 0.7 4.3 1.9 2.8 2.7 0.7 13 73 0 0 0 0 7.95 0.1 22 39.93 0.35 3.87 2.81
11.1 203.73 LV26 1.5 10.9 1.8 101.9 3.1 2.5 19 92 213 146 31 161 9.44 0.1 22 41.99 0.46 3.62 2.95
11.6 203.71 LV27 0.0 15.8 1.5 12.1 1.6 3.5 18 60 186 146 29 42 9.51 0.2 12 51.46 0.15 1.38 1.62
12 203.68 LV28 0.6 5.4 2.1 5.3 2.1 1.3 15 72 112 123 32 69 10.37 0.1 25 30.96 0.22 1.95 0.97
12.6 203.62 LV29 10.9 6.3 7.3 4.3 6.1 3.1 39 225 293 98 67 363 8.81 0.1 18 70.60 0.16 0.77 2.22
13 203.59 LV30 16.0 18.2 5.6 15.5 2.4 0.8 24 143 403 118 37 375 8.12 0.2 17 46.80 0.21 1.46 1.47
13.55 203.54 LV31 4.2 9.9 7.8 15.2 3.2 0.6 14 93 215 96 21 204 6.81 0.1 18 46.29 0.17 1.52 1.46
13.67 203.53 LV32 8.4 4.3 8.8 22.2 5.8 0.5 17 164 25 36 7 38 6.37 0.1 22 25.45 0.20 2.15 0.80
14.5 203.46 LV34 2.2 0.9 3.0 2.2 1.3 0.1 3 13 46 20 5 58 7.25 0.1 25 34.45 0.18 1.89 1.08
15.1 203.41 LV35 3.3 10.2 4.8 5.5 2.4 0.5 16 145 305 113 28 254 8.72 0.1 22 36.34 0.18 1.82 1.14
15.5 203.38 LV36 13.2 4.9 21.3 6.6 9.3 0.3 16 72 453 106 49 385 6.11 0.1 25 27.77 0.21 2.07 0.87
16 203.33 LV37 9.1 4.1 5.8 53.3 6.6 1.4 13 124 364 436 24 270 5.87 0.1 21 41.06 0.17 1.68 1.29
16.5 203.29 LV38 14.1 3.1 9.4 9.8 5.6 0.2 14 43 256 111 22 197 5.33 0.1 23 26.39 0.15 2.17 0.83
17 203.25 LV39 23.9 4.2 14.6 10.3 6.0 0.4 22 92 276 89 34 407 5.44 0.1 21 49.57 0.16 1.43 1.56
17.5 203.20 LV40 16.6 7.6 37.1 4.2 7.7 0.8 24 55 407 96 68 508 6.01 0.1 15 44.05 0.13 1.63 1.39
18 203.16 LV41 11.7 6.5 5.1 9.9 1.9 0.3 10 57 150 193 17 177 7.34 0.1 13 37.33 0.10 1.87 1.17
18.5 203.12 LV42 19.6 3.3 6.5 42.5 5.8 0.2 15 76 294 54 16 313 6.68 0.1 28 64.07 0.27 0.86 2.02
19 203.08 LV43 4.1 8.8 3.0 32.7 3.3 1.9 15 109 266 133 33 163 8.57 0.1 21 33.42 0.18 1.92 1.05
19.5 203.03 LV44 14.8 10.0 7.6 4.0 7.5 1.3 43 230 331 67 58 366 8.48 0.2 24 68.98 0.33 0.64 2.17
20 202.99 LV45 8.9 5.1 8.7 43.9 2.9 0.9 17 103 240 98 24 336 6.11 0.1 23 32.49 0.17 1.95 1.02
20.45 202.95 LV46 13.3 5.6 20.7 12.1 7.4 0.3 17 59 457 85 44 452 5.05 0.1 23 28.17 0.18 2.08 0.89
21 202.90 LV47 10.8 11.0 4.4 25.0 1.7 1.2 14 78 175 120 24 307 6.34 0.1 20 37.16 0.12 1.85 1.17
21.5 202.86 LV48 22.0 5.0 12.3 18.7 9.1 0.2 22 59 373 94 32 400 5.97 0.1 22 25.77 0.15 2.19 0.81
21.9 202.83 LV49 27.0 5.7 9.2 23.5 5.4 1.1 21 107 413 96 27 422 5.93 0.1 20 42.05 0.18 1.65 1.32
22.5 202.77 LV50 5.78 0.1 5 48.41 0.03 1.60 1.52
23 202.73 LV51 13.6 12.4 9.7 18.6 2.0 1.9 17 100 354 125 28 356 6.84 0.1 13 44.65 0.12 1.62 1.40
23.5 202.69 LV52 15.3 3.6 3.7 8.1 2.8 0.9 15 110 245 114 36 279 7.74 0.1 22 44.34 0.21 1.54 1.40
24 202.65 LV53 15.5 4.0 3.4 5.7 3.5 0.3 9 82 140 122 16 149 7.71 0.1 20 30.78 0.15 2.03 0.97
282
Meter Age Sample Cd (ppm) Pb (ppm) Mo (ppm) Re (ppm) U (ppm) Co (ppm) Cu (ppm) Cr (ppm) V (ppm) Mn (ppm) Ni (ppm) Zn (ppm) δ15N % N C:N %Detrital MARtoc MARcac03 MARdetrital
24.5 202.60 LV54 12.8 9.7 4.6 16.5 3.1 0.8 22 146 212 67 39 303 7.91 0.2 31 66.65 0.35 0.70 2.10
25 202.56 LV55 17.7 2.5 13.3 11.4 4.5 0.2 16 58 262 98 25 360 5.68 0.1 29 30.54 0.16 2.03 0.96
25.52 202.52 LV56 2.1 4.0 7.8 3.5 1.0 0.9 5 8 96 169 22 189 5.73 0.2 11 16.16 0.14 2.49 0.51
26 202.47 LV57 20.6 1.9 4.0 10.7 3.3 0.3 15 101 307 100 24 340 5.22 0.1 24 33.34 0.21 1.89 1.05
26.45 202.44 LV58 51.6 4.2 11.0 42.9 10.8 0.3 22 73 510 171 33 459 4.68 0.1 24 26.80 0.24 2.06 0.84
27.1 202.38 LV59 41.2 2.4 8.3 5.4 4.4 0.3 15 75 246 106 26 313 5.17 0.1 22 35.01 0.36 4.35 2.54
27.55 202.36 LV60 40.7 1.9 4.3 17.5 3.7 0.6 17 158 258 124 33 363 6.58 0.1 30 37.13 0.57 3.99 2.69
28 202.35 LV61 37.1 9.1 8.3 23.4 4.1 0.4 21 119 377 107 39 610 6.48 0.2 19 41.33 0.47 3.77 2.99
28.5 202.33 LV62 17.9 3.2 18.0 1.2 12.9 1.0 34 176 409 56 62 520 6.16 0.1 12 88.59 0.19 0.64 6.41
28.95 202.31 LV63 15.5 3.5 4.4 1.3 5.3 1.6 33 178 227 87 68 416 7.36 0.1 15 76.66 0.20 1.49 5.55
29.45 202.29 LV64 19.8 4.4 9.8 19.8 6.4 0.5 19 112 316 120 37 553 5.47 0.1 25 38.04 0.50 3.99 2.75
30 202.27 LV65 9.5 5.4 3.2 1.8 5.4 0.5 17 136 202 81 22 216 6.55 0.1 19 51.81 0.27 3.22 3.75
30.6 202.25 LV66 57.9 4.0 19.3 7.7 5.7 0.4 19 55 285 171 37 523 4.79 0.1 25 40.50 0.41 3.90 2.93
31 202.23 LV67 30.6 3.1 4.5 16.2 2.4 0.2 11 86 248 98 23 325 5.95 0.1 20 32.28 0.37 4.53 2.34
31.55 202.21 LV68 13.7 13.6 25.1 1.0 12.5 2.8 40 302 457 215 113 643 6.42 0.1 8 88.06 0.16 0.70 6.38
32 202.20 LV69 6.0 4.3 3.8 15.2 2.1 0.4 18 110 187 136 29 299 6.97 0.1 24 37.06 0.48 4.08 2.68
32.5 202.18 LV70 24.0 21.3 28.1 3.2 6.7 3.3 35 67 421 153 63 753 5.80 0.1 7 52.33 0.14 3.31 3.79
33 202.16 LV71 30.3 9.6 65.6 3.1 17.7 1.0 35 81 641 75 121 626 4.62 0.2 21 63.73 1.35 3.72 8.90
33.43 202.15 LV72 18.6 11.5 15.7 17.2 3.3 0.5 23 79 377 94 49 580 4.97 0.2 16 47.68 0.81 6.50 6.66
34 202.14 LV73 37.9 5.8 13.3 12.4 4.4 0.2 18 61 305 82 25 386 4.27 0.1 30 37.40 0.76 7.98 5.22
34.5 202.13 LV74 21.0 4.0 13.3 24.9 4.0 0.3 15 68 272 108 30 380 4.90 0.1 20 33.24 0.76 8.56 4.64
35 202.12 LV75 28.9 2.9 13.5 12.3 10.4 0.3 21 72 371 111 44 439 4.60 0.1 24 30.53 0.88 8.82 4.26
35.5 202.11 LV76 3.3 1.5 10.0 35.9 4.6 0.1 8 21 263 138 20 133 3.17 0.1 21 9.03 0.72 11.99 1.26
36 202.10 LV77 13.1 7.7 10.7 10.7 2.7 0.5 12 51 309 112 28 406 5.46 0.1 29 33.04 1.12 8.23 4.61
36.4 202.09 LV78 40.9 4.3 13.7 8.7 7.8 1.0 27 198 355 93 65 484 6.11 0.1 29 60.25 1.19 4.36 8.41
37 202.08 LV79 25.0 4.5 6.0 6.4 2.7 0.3 13 78 264 116 29 373 6.18 0.1 18 24.50 0.62 9.92 3.42
37.5 202.07 LV80 24.9 2.8 7.4 7.2 4.7 0.3 15 107 291 93 34 389 5.64 0.1 23 33.81 0.91 8.33 4.72
38 202.06 LV81 1.6 3.3 3.3 14.5 3.9 1.0 21 133 250 92 41 173 6.88 0.1 23 32.32 1.05 8.40 4.51
38.1 202.05 LV83 14.3 5.1 17.4 21.0 4.5 0.7 14 32 290 85 37 454 3.82 0.1 21 28.24 0.72 9.30 3.94
38.45 202.06 LV84 25.5 5.8 13.1 4.2 2.7 0.5 23 117 428 62 53 581 4.96 0.1 28 43.87 0.97 6.87 6.13
38.45 202.05 LV82 6.1 2.9 16.5 21.2 6.4 0.3 14 43 329 87 31 281 4.71 0.2 15 49.19 0.92 6.18 6.87
39 202.04 LV85 18.8 5.4 26.3 1.6 6.9 0.9 22 39 282 65 46 427 4.53 0.0 11 44.88 0.16 7.54 6.27
39.6 202.03 LV86 52.6 11.3 13.9 9.3 7.2 0.5 22 81 400 62 44 568 4.56 0.2 14 48.41 0.90 6.31 6.76
40 202.02 LV87 20.7 9.2 10.8 21.7 3.0 0.4 12 64 247 87 30 493 4.58 0.1 13 40.46 0.51 7.81 5.65
40.5 202.02 LV88 32.1 5.3 21.2 6.9 6.9 0.2 19 31 404 89 37 411 2.80 0.1 22 28.90 0.84 9.09 4.04
41 202.01 LV89 31.4 3.3 20.2 5.3 11.3 0.2 15 41 400 92 37 305 2.74 0.1 23 23.54 0.92 9.76 3.29
41.3 202.00 LV90 46.4 7.2 7.0 19.3 4.4 0.9 22 44 303 118 35 527 2.71 0.3 9 45.65 0.81 6.78 6.37
41.5 202.00 LV91 42.2 4.6 4.5 1.7 3.4 1.5 13 54 247 129 31 466 2.46 0.1 15 44.06 0.30 7.51 6.15
42 201.99 LV92 10.5 7.9 11.1 1.2 4.8 1.2 42 160 239 50 58 651 1.87 0.1 17 87.32 0.33 1.44 12.19
42.5 201.98 LV93 19.4 9.1 16.4 1.1 3.4 1.4 32 94 270 163 74 912 5.88 0.1 6 47.06 0.19 7.21 6.57
43 201.97 LV94 14.4 8.5 15.6 0.6 1.9 1.7 27 62 214 129 69 817 4.88 0.1 5 51.32 0.21 6.59 7.17
43.5 201.96 LV95 28.9 8.7 10.1 24.5 6.0 1.5 20 78 242 99 28 490 5.74 0.1 26 40.96 1.03 7.21 5.72
44 201.95 LV96 19.2 6.9 13.8 25.7 6.3 1.9 21 80 291 107 33 412 5.35 0.1 35 40.45 1.42 6.90 5.65
44.65 201.93 LV97 23.4 4.3 26.2 10.0 7.1 0.3 18 33 302 94 37 378 3.58 0.1 27 38.25 0.82 7.80 5.34
45 201.93 LV98 12.7 5.0 9.2 15.8 4.0 0.2 12 38 235 134 27 436 2.39 0.1 26 32.37 0.59 8.85 4.52
45.5 201.92 LV99 31.0 2.6 14.6 18.8 10.7 0.2 15 36 441 143 38 453 3.31 0.1 24 24.38 0.90 9.66 3.41
46 201.91 LV100 2.5 2.5 3.3 2.2 0.7 0.6 6 20 75 38 16 218 4.57 0.1 13 53.79 0.55 5.91 7.51
46.5 201.90 LV101 28.2 4.3 15.1 29.2 12.6 0.2 27 50 375 90 29 350 3.81 0.1 37 35.72 1.21 7.77 4.99
47 201.89 LV102 2.9 1.3 1.0 14.2 0.9 0.2 4 15 51 23 4 97 42.09 1.02 7.06 5.88
47.5 201.88 LV103 37.9 2.9 17.6 12.1 8.0 0.3 19 62 324 111 32 673 4.1 0.1 28 34.94 0.81 8.27 4.88
48 201.87 LV104 26.3 5.1 15.4 14.7 4.6 0.3 19 35 246 93 29 478 4.5 0.1 25 32.66 0.29 3.75 1.96
48.5 201.85 LV105 62.0 2.9 9.4 25.0 6.6 0.3 24 89 410 99 33 673 4.9 0.2 15 35.14 0.42 3.47 2.11
49.05 201.82 LV106 29.8 2.3 11.9 58.7 6.9 0.2 21 43 378 103 34 493 3.1 0.1 31 29.74 0.45 3.76 1.78
49.5 201.80 LV107 23.6 7.2 14.3 5.1 16.3 3.4 35 62 731 129 119 1168 3.9 0.1 12 41.84 0.22 3.27 2.51
283
Meter Age Sample Cd (ppm) Pb (ppm) Mo (ppm) Re (ppm) U (ppm) Co (ppm) Cu (ppm) Cr (ppm) V (ppm) Mn (ppm) Ni (ppm) Zn (ppm) δ15N % N C:N %Detrital MARtoc MARcac03 MARdetrital
50 201.78 LV108 67.5 6.0 19.5 23.4 9.2 0.2 28 60 531 81 50 835 3.0 0.1 31 30.83 0.50 3.65 1.85
50.5 201.76 LV109 17.9 5.3 8.9 1.6 1.2 0.7 14 7 234 117 52 592 3.5 0.2 4 25.15 0.11 4.38 1.51
51.05 201.73 LV110 32.8 11.3 10.8 39.6 4.9 0.2 20 45 527 78 48 747 1.8 0.1 21 20.98 0.32 4.42 1.26
51.55 201.71 LV111 7.9 4.2 42.4 407.6 16.7 0.5 17 42 621 58 122 411 2.1 0.1 31 13.00 0.61 4.61 0.78
52 201.69 LV112 29.3 3.1 31.5 35.1 10.9 0.3 25 48 690 64 92 656 2.8 0.1 36 23.03 0.73 3.89 1.38
52.5 201.67 LV113 19.9 6.2 36.6 177.9 15.4 1.2 31 69 468 68 60 431 4.1 0.2 21 37.27 0.62 3.15 2.24
53 201.65 LV114 5.5 2.2 44.1 46.0 6.9 1.2 11 28 383 76 83 375 1.5 0.1 33 19.30 0.41 4.44 1.16
53.5 201.62 LV115 11.7 4.5 30.2 18.7 5.9 0.7 11 29 505 85 65 372 2.8 0.1 30 22.27 0.41 4.25 1.34
54 201.60 LV116 3.8 3.5 48.3 199.8 9.5 0.6 14 20 346 55 73 130 1.5 0.1 31 20.94 0.59 4.16 1.26
54.55 201.58 LV117 13.0 4.2 40.3 31.4 12.4 0.2 13 34 624 60 99 393 1.5 0.1 32 30.93 0.54 3.61 1.86
54.85 201.56 LV118 17.5 7.3 47.3 2.2 8.2 2.1 19 46 563 106 90 722 3.4 0.1 18 42.30 0.17 3.30 2.54
55.45 201.53 LV119 13.8 5.3 27.0 5.6 4.9 1.0 13 28 408 106 58 446 2.5 0.1 24 26.15 0.20 4.23 1.57
56 201.51 LV120 4.9 3.6 5.4 8.6 0.9 0.2 5 4 174 105 39 314 2.2 0.2 9 21.24 0.42 9.33 2.63
56.5 201.50 LV121 11.3 3.5 26.1 12.4 8.2 0.1 12 34 438 92 35 239 1.8 0.1 36 16.93 0.84 9.44 2.10
57.1 201.49 LV122 1.8 10.3 39.2 14.4 3.7 6.6 22 14 48 182 35 136 3.1 0.1 9 55.59 0.28 5.21 6.88
57.5 201.48 LV123 0.7 8.3 37.9 315.9 3.1 4.7 17 21 32 251 29 71 3.1 0.1 21 45.64 0.58 6.14 5.65
58 201.47 LV124 0.6 3.7 8.7 7.9 1.6 0.6 7 7 17 281 15 100 3.2 0.1 36 27.01 0.77 8.26 3.34
58.5 201.46 LV125 0.4 3.4 7.8 1.9 1.4 3.3 10 4 24 277 20 55 2.4 0.1 16 32.36 0.58 7.79 4.00
59 201.44 LV126 0.4 2.0 2.5 11.3 1.0 0.9 2 2 7 303 9 38 1.9 0.2 9 22.51 0.39 9.20 2.79
59.15 201.44 LV127 0.6 11.1 11.8 0.9 4.0 5.7 16 13 33 155 23 41 2.8 0.2 6 74.04 0.24 2.97 9.16
60 201.42 LV128 0.3 4.0 5.0 33.0 2.4 1.2 9 6 18 279 13 55 3.1 0.1 31 24.45 0.50 8.85 3.03
60.5 201.41 LV129 2.7 13.7 16.2 39.8 9.0 3.0 30 60 57 131 83 202 3.2 0.2 28 63.41 1.24 3.28 7.85
61 201.40 LV130 0.6 6.6 10.5 128.7 3.3 3.5 13 8 20 104 28 31 2.9 0.1 30 58.24 1.04 4.13 7.21
61.5 201.39 LV131 0.5 10.6 11.3 2.2 2.9 5.7 16 12 38 197 34 51 2.2 0.1 7 59.05 0.13 3.81 5.69
62 201.38 LV132 1.0 4.4 7.1 15.6 1.6 1.2 9 20 25 222 20 84 2.6 0.1 18 30.40 0.25 6.46 2.93
62.5 201.36 LV133 0.5 5.7 8.2 3.9 3.0 2.5 11 10 24 146 31 23 2.6 0.1 21 43.55 0.37 5.07 4.20
63 201.35 LV134 0.7 7.5 3.0 341.7 4.2 4.9 13 8 22 142 16 103 2.4 0.1 36 37.81 0.88 5.12 3.65
63.45 201.34 LV135 0.4 3.4 4.8 0.2 1.2 1.3 8 3 9 18 16 50 2.5 0.1 7 81.91 0.22 1.52 7.90
64 201.32 LV136 0.4 10.5 5.2 0.4 2.2 8.0 22 21 25 140 17 41 2.6 0.1 4 72.37 0.05 1.05 2.88
64.5 201.29 LV137 0.3 5.6 3.5 183.7 2.9 4.4 11 7 19 243 24 61 2.4 0.1 27 32.50 0.17 2.52 1.29
65.05 201.25 LV138 0.1 3.6 2.9 19.1 2.8 1.3 8 4 19 242 13 30 2.1 0.1 37 19.19 0.18 3.04 0.76
65.5 201.22 LV139 2.2 7.1 8.4 0.6 6.1 3.2 22 13 52 94 46 118 2.3 0.1 13 56.87 0.07 1.65 2.26
66 201.18 LV140 0.6 7.5 10.3 0.8 4.9 5.4 29 16 56 161 80 92 2.4 0.1 9 59.37 0.06 1.55 2.36
66.5 201.15 LV141 0.4 4.8 4.1 2.1 2.5 4.1 15 6 32 259 20 53 2.0 0.1 9 46.22 0.07 2.07 1.84
67 201.12 LV142 1.8 4.5 4.9 0.7 2.9 2.5 18 8 29 105 37 77 2.4 0.1 18 49.08 0.09 1.94 1.95
67.45 201.09 LV143 5.1 2.5 1.4 9.1 1.7 1.6 8 5 34 164 27 119 2.5 0.0 21 35.40 0.09 2.48 1.41
68 201.05 LV144 12.6 2.5 2.2 0.6 2.2 0.9 9 10 47 147 47 300 2.5 0.0 21 35.30 0.07 2.50 1.41
68.5 201.01 LV145 9.6 2.1 1.8 13.5 1.5 0.6 6 4 29 142 26 166 2.1 0.1 35 30.90 0.18 2.57 1.23
69 200.98 LV146 9.7 4.4 3.7 0.5 2.6 1.4 17 7 40 112 130 342 2.8 0.1 11 54.37 0.06 1.76 2.16
69.5 200.95 LV147 4.3 2.2 3.1 1.2 1.6 1.0 7 4 33 163 28 159 2.5 0.0 21 36.87 0.06 2.45 1.47
70 200.91 LV148 5.9 2.7 2.2 0.6 2.7 7.6 9 8 44 441 40 245 2.5 0.0 17 37.59 0.06 2.42 1.50
70.5 200.88 LV149 5.4 4.7 5.6 1.8 4.0 2.8 18 8 42 133 38 171 2.2 0.1 19 53.38 0.09 1.76 2.12
70.8 200.86 LV150 11.8 2.6 3.4 0.5 2.2 0.6 9 6 48 90 48 300 2.8 0.0 15 43.88 0.06 2.17 1.75
71.5 200.81 LV151 9.0 7.2 12.3 0.4 3.9 5.3 14 11 91 133 62 272 2.6 0.1 10 46.46 0.04 1.73 1.54
72 200.77 LV153 16.4 13.8 89.5 0.5 2.0 14.1 97 30 215 61 162 1051 3.0 0.1 13 94.96 -0.16 -0.04 -3.78
72.1 200.78 LV152 30.9 7.8 25.6 0.7 36.1 2.1 27 32 250 8 889 1297 1.4 0.1 10 97.16 0.07 0.03 3.16
72.55 200.74 LV154 6.0 7.0 14.5 0.6 3.3 1.5 14 9 117 120 74 285 2.2 0.0 12 33.20 0.27 13.07 6.63
73 200.73 LV155 5.2 8.2 37.3 0.7 6.0 3.1 19 20 164 140 85 441 2.2 0.1 11 37.66 0.27 12.18 7.52
73.45 200.73 LV156 4.3 9.2 58.1 0.5 6.1 5.5 20 15 199 171 115 749 2.4 0.1 8 37.93 0.27 12.13 7.57
74 200.72 LV157 3.5 2.0 2.6 0.4 1.3 0.8 6 4 219 167 206 611 2.3 0.1 11 58.47 0.56 7.74 11.68
74.4 200.71 LV158 5.5 8.8 87.5 0.6 6.7 14.3 27 25 228 165 117 937 2.4 0.1 8 44.73 0.26 10.78 8.93
74.9 200.71 LV159 0.9 5.3 27.0 8.6 4.0 0.6 12 17 128 136 62 188 2.1 0.1 28 23.43 0.74 14.55 4.68
75.5 200.70 LV160 2.7 13.4 65.9 0.6 8.0 1.8 32 32 196 85 204 400 2.5 0.1 7 66.81 0.37 6.26 13.34
76 200.69 LV161 1.3 3.5 10.0 1.7 1.7 0.8 7 14 98 121 36 100 2.2 0.1 9 25.65 0.34 14.51 5.12
284
Meter Age Sample Cd (ppm) Pb (ppm) Mo (ppm) Re (ppm) U (ppm) Co (ppm) Cu (ppm) Cr (ppm) V (ppm) Mn (ppm) Ni (ppm) Zn (ppm) δ15N % N C:N %Detrital MARtoc MARcac03 MARdetrital
76.3 200.69 LV162 1.2 6.2 28.9 27.7 3.9 2.1 15 17 100 139 73 138 2.0 0.1 28 28.85 1.09 13.12 5.76
76.5 200.69 LV163 1.6 8.1 28.8 0.7 4.8 3.2 18 16 137 101 84 160 2.3 0.1 9 50.74 0.27 9.57 10.13
76.9 200.68 LV164 1.2 8.4 31.6 0.6 4.6 4.0 22 27 155 128 98 135 2.5 0.1 8 45.46 0.27 10.62 9.08
77.5 200.67 LV165 0.5 5.0 29.9 78.6 3.7 3.3 11 17 45 255 64 49 2.0 0.1 31 21.73 0.90 14.74 4.34
78.1 200.66 LV166 0.9 7.2 37.5 101.8 5.0 2.0 18 14 116 148 71 104 2.0 0.1 32 24.34 1.35 13.76 4.86
78.5 200.66 LV167 2.2 7.3 29.2 0.8 4.6 1.5 17 13 157 175 69 211 1.9 0.1 11 32.52 0.30 13.18 6.49
79 200.65 LV168 0.9 8.4 12.1 1.5 3.6 4.4 17 20 184 182 59 124 2.4 0.1 7 44.73 0.26 10.78 8.93
79.5 200.65 LV169 2.9 7.9 21.9 0.7 5.8 0.9 20 30 178 133 106 325 2.4 0.1 9 45.14 0.33 10.63 9.02
80 200.64 LV170 2.2 7.3 40.8 0.9 6.9 3.3 20 19 229 191 70 204 4.9 0.1 5 35.23 0.23 12.71 7.04
80.5 200.63 LV171 6.5 10.3 13.6 3.3 7.3 0.7 18 19 188 242 314 381 1.8 0.1 17 31.56 0.75 12.92 6.30
81 200.63 LV172 2.2 6.6 11.8 1.6 3.1 3.1 17 23 152 201 32 161 2.8 0.1 8 37.63 0.22 12.24 7.52
81.5 200.62 LV173 0.4 4.4 9.3 12.6 1.2 3.0 13 7 27 348 13 18 5.3 0.1 8 25.40 0.32 14.58 5.07
82 200.61 LV174 4.9 34.9 72.9 0.7 9.8 9.4 58 22 274 177 159 651 2.3 0.2 4 84.34 0.35 2.77 16.84
82.5 200.61 LV175 2.7 9.5 21.8 0.6 4.1 4.1 19 18 221 304 91 214 1.9 0.1 6 40.93
82.5 200.61 LV176 3.6 13.9 60.8 0.4 6.8 7.3 45 27 255 141 135 394 4.7 0.1 10 85.79 0.30 2.53 17.13
83 200.60 LV177 4.4 9.4 18.5 0.8 6.7 2.1 20 26 71 63 19 118 2.3 0.1 8 44.10
83 200.60 LV178A 2.2 6.1 13.5 1.7 4.2 1.8 14 19 157 242 48 261 2.2 0.1 8 32.05 0.27 13.30 6.40
83.25 200.60 LV178B 0.4 5.6 21.2 44.3 3.5 3.2 12 13 85 231 50 42 3.1 0.1 15 26.74 0.54 14.09 5.34
83.5 200.59 LV179 4.9 6.4 11.1 1.1 4.9 2.4 17 21 197 216 45 264 2.0 0.1 6 36.67 0.20 12.45 7.32
84 200.59 LV180 0.2 6.2 18.5 20.7 4.7 3.1 12 13 96 296 54 47 2.5 0.1 16 24.95 0.47 14.51 4.98
84.1 200.58 LV181 9.1 49.3 88.0 1.0 20.1 8.0 77 56 533 244 211 1493 2.9 0.2 5 79.32 0.37 3.76 15.84
84.5 200.58 LV182 1.5 16.3 45.0 0.2 5.2 5.2 37 27 205 197 119 143 2.5 0.2 3 88.63 0.23 2.04 17.70
85.2 200.57 LV183 24.1 24.9 26.5 0.8 10.2 4.1 44 50 401 275 101 1296 2.2 0.1 8 63.50 0.49 6.80 12.68
85.5 200.56 LV184 4.6 10.1 11.7 2.1 5.1 2.2 16 24 202 184 32 168 2.7 0.1 9 33.49 0.28 13.00 6.69
86 200.56 LV185 0.1 7.0 16.9 104.4 2.7 3.0 12 11 69 233 42 46 2.4 0.1 20 27.06 0.69 13.88 5.40
86.5 200.55 LV186 6.9 26.1 59.3 1.4 13.4 10.3 44 32 386 308 169 863 2.4 0.1 6 70.76 0.39 5.45 14.13
87 200.54 LV187 0.7 9.8 33.6 1.1 4.4 4.1 17 22 131 164 53 109 2.6 0.1 6 42.77 0.20 11.23 8.54
87.5 200.54 LV188 23.7 19.5 49.6 0.7 11.9 6.8 39 42 395 279 131 1425 2.5 0.1 4 69.35 0.27 5.85 13.85
88 200.53 LV189 8.5 18.8 35.2 0.9 10.8 6.6 40 44 299 226 148 1038 2.6 0.2 4 74.44 0.30 4.80 14.87
88.25 200.53 LV190 0.5 2.2 11.3 12.4 2.8 0.9 5 13 104 160 24 32 2.3 0.0 18 9.89 0.23 17.76 1.98
88.5 200.52 LV191 1.9 14.3 15.6 0.7 13.3 7.3 29 27 219 205 132 195 2.5 0.1 4 71.80 0.22 5.41 14.34
89 200.52 LV192 5.1 18.5 14.8 1.5 10.4 7.0 30 35 289 276 133 625 2.9 0.1 4 60.96 0.24 7.56 12.17
89.5 200.51 LV193 6.9 22.7 24.0 1.6 10.1 9.4 37 52 337 358 185 639 2.7 0.1 3 64.26 0.21 6.93 12.83
90 200.50 LV194 1.2 10.1 8.8 1.4 4.4 4.0 16 38 215 231 63 117 3.1 0.1 6 31.60 0.16 13.50 6.31
90.5 200.50 LV195 11.6 23.4 25.3 0.6 11.9 9.4 46 48 308 191 144 976 2.7 0.2 4 82.65 0.28 3.19 16.51
91 200.49 LV196 2.3 12.3 2.1 0.9 2.5 4.1 18 31 127 238 28 73 2.8 0.1 6 40.67 0.27 11.58 8.12
91.5 200.48 LV197 2.0 18.8 4.2 0.5 2.3 6.8 33 45 175 416 64 107 3.0 0.1 3 72.54 0.20 5.28 14.49
92 200.48 LV198 0.3 6.6 1.8 5.5 1.8 3.1 14 29 60 738 15 232 2.7 0.1 12 25.51 0.31 14.56 5.10
92.5 200.47 LV199 1.3 48.6 11.5 0.9 6.8 13.5 64 58 140 342 100 82 3.0 0.2 3 90.84 0.25 1.58 18.14
93 200.46 LV200 0.2 9.8 1.9 0.4 0.6 3.4 20 25 64 266 28 28 3.0 0.1 6 45.98 0.19 10.59 9.18
93.3 200.46 LV201 0.6 5.6 1.2 12.7 0.6 2.3 11 25 46 295 18 34 4.2 0.0 13 27.70 0.27 14.17 5.53
93.5 200.46 LV202 15.4 20.4 4.3 0.6 3.9 5.7 52 72 101 223 51 581 3.7 0.1 6 75.40 0.39 4.52 15.06
94 200.45 LV203 14.9 7.4 2.1 0.4 0.6 1.4 15 39 70 316 26 242 3.5 0.1 9 31.52 0.10 6.20 2.90
94.5 200.44 LV204 14.4 9.2 5.8 0.3 2.2 4.3 25 54 119 218 45 387 2.7 0.1 6 48.43 0.10 4.64 4.45
95 200.42 LV205 2.1 30.0 5.8 0.3 5.0 7.6 60 71 138 245 80 129 3.4 0.2 6 72.33 0.25 2.30 6.65
95.5 200.41 LV206 0.2 7.0 1.3 0.2 2.0 3.3 13 20 92 561 20 32 3.5 0.1 7 28.31 0.09 6.50 2.60
96 200.39 LV207 4.1 27.6 4.2 0.5 6.2 10.1 53 56 166 222 42 104 2.8 0.2 4 81.00 0.13 1.62 7.45
96.5 200.38 LV208 0.2 12.6 1.5 0.6 0.9 6.1 25 19 51 394 30 34 3.3 0.1 5 57.42 0.15 3.77 5.28
96.9 200.36 LV209 0.0 4.9 0.7 0.7 1.1 1.2 12 14 38 1020 9 27 3.5 0.1 9 30.73 0.12 6.25 2.82
97.5 200.35 LV210 0.2 10.3 1.6 0.5 1.4 5.6 21 19 56 382 22 25 2.9 0.1 3 44.48 0.06 5.05 4.09
98 200.33 LV211 0.1 9.2 1.3 0.3 0.8 3.1 21 15 46 310 25 25 3.3 0.1 3 55.65 0.05 4.02 5.12
98.5 200.32 LV212 0.3 8.1 1.2 0.2 0.7 2.2 17 18 49 332 18 28 3.0 0.1 3 51.08 0.07 4.43 4.70
99 200.30 LV213 2.4 3.1 1.9 0.2 0.6 0.6 5 10 22 292 13 80 2.0 0.1 2 26.43 0.04 6.72 2.43
99.5 200.29 LV214 0.2 4.3 0.7 0.4 0.5 0.8 9 11 35 555 11 126 3.2 0.0 10 28.81 0.11 6.44 2.65
285
Meter Age Sample Cd (ppm) Pb (ppm) Mo (ppm) Re (ppm) U (ppm) Co (ppm) Cu (ppm) Cr (ppm) V (ppm) Mn (ppm) Ni (ppm) Zn (ppm) δ15N % N C:N %Detrital MARtoc MARcac03 MARdetrital
100 200.27 LV215 1.8 7.9 0.9 0.4 1.2 2.6 18 20 57 369 27 81 4.0 0.1 5 46.84 0.07 4.81 4.31
100.5 200.26 LV216 1.9 23.7 3.4 0.1 1.7 4.7 56 39 95 65 52 379 3.8 0.2 5 97.82 0.15 0.05 8.99
100.9 200.25 LV217 0.1 3.6 0.5 1.4 0.8 1.1 9 16 37 439 11 54 4.9 0.0 19 31.60 0.16 6.12 2.90
101.5 200.23 LV218 1.1 18.9 1.8 0.2 2.7 2.8 40 23 82 60 40 216 4.2 0.1 6 93.89 0.14 0.42 8.63
102 200.22 LV219 0.4 4.3 0.7 3.3 0.4 1.6 9 10 35 459 16 32 4.7 0.0 19 30.57
102 200.22 LV220 1.5 27.2 8.4 0.1 2.8 9.1 58 38 104 170 88 398 3.5 0.2 3 94.67 0.12 0.37 8.70
102.5 200.20 LV221 3.1 14.5 1.8 2.0 2.4 1.4 27 27 111 637 39 267 4.2 0.1 13 38.86 0.22 5.40 3.57
103 200.19 LV222 1.5 31.3 6.3 0.1 2.6 9.2 52 39 113 149 63 264 3.7 0.2 3 91.07 0.14 0.68 8.37
103.5 200.17 LV223 0.3 3.8 0.5 0.4 0.6 0.6 8 12 40 384 8 60 4.7 0.0 16 36.07 0.12 5.75 3.32
104 200.16 LV224 1.0 21.0 3.4 0.5 3.5 7.4 37 22 88 165 48 563 3.6 0.1 4 93.76 0.11 0.46 8.62
104.5 200.14 LV225 0.2 8.2 0.7 0.6 0.5 0.8 13 13 42 352 15 54 4.4 0.1 16 44.34 0.20 4.92 4.08
105 200.13 LV226 1.0 4.5 0.7 0.2 0.3 0.2 6 9 36 390 16 97 2.6 0.1 5 30.77
105 200.13 LV227 0.5 24.5 1.8 0.5 2.3 5.2 32 27 70 77 30 112 4.6 0.1 5 96.02
286
Table 3.1. Correlation coefficients for data in Appendix H1
NOTE THAT ABOVE THE DIAGONAL REFERENCES DATA FROM 201.5 MA TO THE TOP OF THE SECTION
BELOW THE DIAGONAL REFERENCES DATA FROM 204 MA TO 201.5 MA
>.3 >.7
Cd Pb Mo Re U Co Cu Cr V Mn Ni Zn TOC δ13Corg δ13Ccarb %CARBδ15N %N C:N MAR
bulk
MAR
TOC
MAR
CACO3
MAR
DETRITAL
Cd 0.00 0.04 0.08 0.02 0.34 0.03 0.11 0.14 0.25 0.04 0.36 0.59 0.01 0.01 0.01 0.09 0.05 0.01 0.01 0.01 0.03 0.06 0.01
Pb 0.02 0.00 0.12 0.00 0.18 0.50 0.75 0.57 0.35 0.00 0.06 0.23 0.03 0.03 0.13 0.52 0.03 0.56 0.21 0.05 0.00 0.11 0.48
Mo 0.05 0.00 0.00 0.00 0.25 0.23 0.25 0.06 0.44 0.07 0.15 0.38 0.00 0.04 0.01 0.07 0.03 0.06 0.01 0.14 0.03 0.01 0.19
Re 0.00 0.02 0.12 0.00 0.00 0.00 0.02 0.03 0.05 0.00 0.01 0.03 0.38 0.01 0.04 0.01 0.01 0.00 0.25 0.00 0.22 0.00 0.02
U 0.15 0.01 0.51 0.14 0.00 0.10 0.17 0.17 0.48 0.06 0.73 0.50 0.00 0.04 0.02 0.18 0.08 0.09 0.03 0.05 0.01 0.01 0.19
Co 0.11 0.37 0.01 0.01 0.00 0.00 0.58 0.30 0.22 0.01 0.03 0.19 0.02 0.01 0.03 0.41 0.00 0.35 0.17 0.01 0.03 0.12 0.22
Cu 0.05 0.19 0.05 0.00 0.21 0.23 0.00 0.54 0.34 0.03 0.10 0.34 0.01 0.00 0.09 0.63 0.03 0.48 0.18 0.00 0.02 0.18 0.28
Cr 0.00 0.09 0.04 0.02 0.00 0.14 0.42 0.00 0.32 0.00 0.07 0.22 0.02 0.08 0.17 0.29 0.03 0.32 0.19 0.09 0.00 0.02 0.35
V 0.23 0.00 0.48 0.07 0.63 0.00 0.18 0.00 0.00 0.01 0.28 0.65 0.06 0.00 0.06 0.14 0.02 0.14 0.17 0.29 0.00 0.01 0.48
Mn 0.08 0.03 0.09 0.01 0.08 0.10 0.02 0.00 0.08 0.00 0.06 0.03 0.03 0.27 0.05 0.12 0.09 0.02 0.01 0.00 0.01 0.02 0.01
Ni 0.02 0.03 0.53 0.08 0.45 0.10 0.33 0.04 0.55 0.04 0.00 0.38 0.00 0.03 0.02 0.15 0.08 0.04 0.02 0.01 0.00 0.02 0.07
Zn 0.41 0.01 0.20 0.00 0.23 0.00 0.28 0.00 0.48 0.09 0.39 0.00 0.01 0.01 0.02 0.21 0.03 0.12 0.07 0.03 0.00 0.03 0.20
TOC 0.01 0.08 0.09 0.17 0.18 0.16 0.00 0.00 0.16 0.15 0.02 0.00 0.00 0.06 0.14 0.01 0.02 0.01 0.63 0.01 0.62 0.00 0.04
δ13Corg 0.01 0.06 0.45 0.17 0.18 0.04 0.02 0.22 0.31 0.07 0.24 0.07 0.11 0.00 0.01 0.00 0.32 0.00 0.08 0.09 0.00 0.06 0.03
δ13Ccarb 0.08 0.07 0.23 0.03 0.20 0.01 0.03 0.00 0.18 0.00 0.18 0.19 0.06 0.21 0.00 0.09 0.07 0.10 0.29 0.02 0.04 0.01 0.10
%TIC 0.00 0.11 0.00 0.05 0.02 0.17 0.47 0.48 0.00 0.03 0.07 0.04 0.00 0.16 0.00 0.00 0.02 0.53 0.20 0.01 0.03 0.48 0.31
d15N 0.22 0.14 0.36 0.06 0.22 0.18 0.01 0.20 0.30 0.13 0.14 0.29 0.07 0.53 0.38 0.09 0.00 0.04 0.02 0.00 0.03 0.02 0.00
%N 0.03 0.03 0.00 0.02 0.01 0.01 0.02 0.00 0.02 0.02 0.02 0.01 0.13 0.00 0.01 0.02 0.00 0.00 0.18 0.02 0.02 0.15 0.37
C:N 0.07 0.21 0.08 0.09 0.110.27 0.03 0.010.10 0.10 0.000.00 0.63 0.11 0.09 0.05 0.13 0.05 0.00 0.05 0.32 0.02 0.24
MARbulk 0.06 0.02 0.01 0.01 0.01 0.03 0.00 0.04 0.00 0.02 0.00 0.06 0.00 0.03 0.08 0.00 0.17 0.00 0.00 0.00 0.20 0.52 0.47
MARTOC 0.12 0.06 0.07 0.02 0.11 0.12 0.00 0.02 0.07 0.08 0.01 0.03 0.36 0.10 0.09 0.00 0.18 0.05 0.26 0.57 0.00 0.17 0.03
MARCACO3 0.03 0.07 0.01 0.00 0.00 0.11 0.09 0.20 0.00 0.00 0.01 0.01 0.00 0.11 0.04 0.18 0.21 0.00 0.02 0.76 0.46 0.00 0.00
MARdetrital 0.04 0.01 0.01 0.05 0.01 0.01 0.15 0.04 0.00 0.03 0.04 0.12 0.01 0.01 0.06 0.31 0.03 0.00 0.03 0.62 0.26 0.15 0.00
287
H.2. NEW YORK CANYON, NEV ADA
Sample ID Meter δ15N stdev
1 18.5 3.39 0.17
2 18.1 3.21
3 17.7 3.64
4 16.0 4.36
5 14.7 3.14
6 14.1 4.76 0.39
7 13.8 3.61
8 12.8 3.41 0.46
9 12.5 4.67
10 11.9 4.96
11 10.7 4.12 0.03
12 10.3 4.79
13 9.2 3.49
14 8.9 5.08
15 8.6 5.05
16 8.2 4.77 0.18
17 6.8 3.72
18 6.6 3.94
19 6.2 3.75
20 6.2 5.17
21 6.0 5.33 0.03
22 6.2 4.97
23 5.8 4.27
24 5.6 4.84
25 5.6 4.04
26 5.1 5.43 0.39
27 4.6 5.12
28 4.2 5.37
29 3.4 5.21
30 2.6 5.43
31 2.3 4.74 0.01
32 -0.2 6.63 0.12
33 -0.9 6.69
34 -1.1 6.58
35 -2.0 5.21
288
Appendix I. Mercury concentration and isotope data (dataset from Chapter 4)
I.1. MERCURY AND CARBON CONCENTRATION DATA
I.1.1. Levanto, Peru
Age Meter Sample Hg (ppb) Hg (ppb)R Average SE RSE Hg (ppb)R n %TOC Hg/TOC
204.16 0 LV1 27.9 29.8 28.9 0.9 3% 2 1.29 22
204.13 0.6 LV2 35.3 1 1.54 23
204.10 1.5 LV4 55.3 1 1.43 39
204.08 2 LV5 16.83 1 0.49 34
204.07 2.15 LV7 41.9 42.7 42.3 0.4 1% 2 0.98 43
204.02 3.6 LV10 24.7 1 1.17 21
204.00 4 LV11 27.4 1 1.96 14
203.96 5 LV13 54.1 56.5 55.3 1.2 2% 2 0.53 102
203.94 5.5 LV14 39.2 1 0.56 69
203.93 6 LV15 25.87 1 1.03 25
203.89 7 LV17 69.1 1 1.40 49
203.87 7.5 LV19 33.7 35.2 34.5 0.7 2% 2 0.66 51
203.83 8.5 LV21 30.1 1 1.89 16
203.81 9.05 LV22 33.0 1 0.93 35
203.77 10 LV24 20.29 1 1.83 11
203.75 10.6 LV25 17.0 19.6 18.3 1.3 7% 2 1.86 9
203.73 11.1 LV26 42.9 1 2.41 18
203.68 12 LV28 28.5 1 2.56 11
203.62 12.6 LV29 32.3 32.4 32.4 0.1 0% 2 1.85 17
203.54 13.55 LV31 50.0 1 2.02 25
203.53 13.67 LV32 19.1 1 2.32 8
203.46 14.5 LV34 24.51 21.14 22.8 1.7 7% 2 2.09 12
203.38 15.5 LV36 25.8 27.7 26.8 0.9 3% 2 2.44 11
289
Age Meter Sample Hg (ppb) Hg (ppb)R Average SE RSE Hg (ppb)R n %TOC Hg/TOC
203.33 16 LV37 29.2 1 2.06 14
203.25 17 LV39 42.0 1 1.90 22
203.20 17.5 LV40 31.3 31.5 31.4 0.1 0% 2 1.51 21
203.12 18.5 LV42 31.5 29.49 30.5 1.0 3% 2 3.19 10
203.08 19 LV43 42.1 1 2.09 20
202.99 20 LV45 25.2 25.4 25.3 0.1 0% 2 2.06 12
202.95 20.45 LV46 29.0 1 2.16 13
202.86 21.5 LV48 36.6 1 1.72 21
202.83 21.9 LV49 65.22 1 2.09 31
202.77 22.5 LV50 29.5 29.6 29.6 0.0 0% 2 0.33 90
202.69 23.5 LV52 21.9 1 2.52 9
202.65 24 LV53 19.9 1 1.75 11
202.56 25 LV55 18.4 20.0 19.2 0.8 4% 2 1.88 10
202.52 25.52 LV56 28.45 1 1.69 17
202.47 26 LV57 12.9 1 2.48 5
202.38 27.1 LV59 22.1 1 1.84 12
202.36 27.55 LV60 12.5 13.0 12.8 0.3 2% 2 2.89 4
202.33 28.5 LV62 31.4 1 0.95 33
202.31 28.95 LV63 16.12 16.01 16.1 0.1 0% 2 1.03 16
202.29 29.45 LV64 29.4 1 2.56 11
202.25 30.6 LV66 26.0 27.5 26.8 0.8 3% 2 2.11 12
202.23 31 LV67 25.4 1 1.91 13
202.20 32 LV69 33.5 1 2.45 14
202.18 32.5 LV70 90.38 1 0.71 127
202.16 33 LV71 57.5 60.8 59.1 1.7 3% 2 3.57 16
202.14 34 LV73 35.7 1 2.01 18
202.13 34.5 LV74 33.9 1 2.02 17
202.12 35 LV75 28.80 1 2.33 12
202.10 36 LV77 43.0 42.9 43.0 0.0 0% 2 2.98 14
290
Age Meter Sample Hg (ppb) Hg (ppb)R Average SE RSE Hg (ppb)R n %TOC Hg/TOC
202.09 36.4 LV78 27.4 1 3.15 9
202.07 37.5 LV80 15.03 1 2.42 6
202.06 38 LV81 27.4 1 2.79 10
202.05 38.1 LV83 36.7 37.8 37.3 0.5 1% 2 1.92 19
202.06 38.45 LV84 35.6 1 2.57 14
202.04 39 LV85 26.07 1 0.41 63
202.03 39.6 LV86 69.4 1 2.38 29
202.02 40.5 LV88 28.8 29.3 29.1 0.3 1% 2 2.23 13
202.01 41 LV89 23.4 1 2.43 10
202.00 41.3 LV90 44.95 44.94 44.9 0.0 0% 2 2.14 21
201.99 42 LV92 36.9 1 0.87 42
201.98 42.5 LV93 56.45 1 0.50 113
201.97 43 LV94 66.1 73.8 70.0 3.8 5% 2 0.56 119
201.95 44 LV96 39.20 1 3.75 10
201.93 44.65 LV97 22.5 1 2.19 10
201.93 45 LV98 31.4 1 1.57 20
201.92 45.5 LV99 21.18 1 2.37 9
201.90 46.5 LV101 31.3 32.6 31.9 0.7 2% 2 3.20 10
201.89 47 LV102 45.82 45.67 45.7 0.1 0% 2 2.72 17
201.88 47.5 LV103 27.4 1 2.15 13
201.85 48.5 LV105 31.14 31.49 31.3 0.2 1% 2 2.61 12
201.82 49.05 LV106 24.7 1 2.79 9
201.80 49.5 LV107 51.8 54.4 53.1 1.3 2% 2 1.36 38
201.78 50 LV108 40.07 1 3.07 13
201.73 51.05 LV110 37.30 1 1.97 19
201.71 51.55 LV111 23.5 1 3.74 6
201.69 52 LV112 32.66 1 4.50 7
201.67 52.5 LV113 32.5 1 3.80 9
201.65 53 LV114 17.50 13.27 15.4 2.1 14% 2 2.51 7
291
Age Meter Sample Hg (ppb) Hg (ppb)R Average SE RSE Hg (ppb)R n %TOC Hg/TOC
201.60 54 LV116 12.91 1 3.63 4
201.58 54.55 LV117 16.1 17.3 16.7 0.6 4% 2 3.32 5
201.56 54.85 LV118 23.49 1 1.03 23
201.53 55.45 LV119 13.64 1 1.23 11
201.51 56 LV120 7.51 1 1.26 6
201.50 56.5 LV121 14.79 1 2.50 6
201.49 57.1 LV122 61.79 1 0.85 73
201.48 57.5 LV123 60.98 1 1.74 35
201.47 58 LV124 36.09 1 2.30 16
201.46 58.5 LV125 37.78 39.50 38.6 0.9 2% 2 1.74 22
201.44 59 LV126 11.29 1 1.17 10
201.44 59.15 LV127 69.88 1 0.73 95
201.42 60 LV128 26.38 1 1.49 18
201.41 60.5 LV129 81.82 81.84 81.8 0.0 0% 2 3.72 22
201.40 61 LV130 40.13 1 3.11 13
201.39 61.5 LV131 36.83 1 0.51 72
201.38 62 LV132 17.64 1 0.95 18
201.36 62.5 LV133 27.59 1 1.43 19
201.35 63 LV134 51.78 1 3.37 15
201.34 63.45 LV135 96.93 1 0.85 113
201.32 64 LV136 49.47 1 0.48 102
201.29 64.5 LV137 24.15 1 1.59 15
201.25 65.05 LV138 28.47 1 1.65 17
201.22 65.5 LV139 43.68 1 0.66 66
201.18 66 LV140 51.95 1 0.60 87
201.15 66.5 LV141 39.79 1 0.65 61
201.12 67 LV142 40.51 1 0.85 48
201.09 67.45 LV143 29.23 1 0.85 34
201.05 68 LV144 39.19 1 0.66 59
292
Age Meter Sample Hg (ppb) Hg (ppb)R Average SE RSE Hg (ppb)R n %TOC Hg/TOC
201.01 68.5 LV145 23.93 1 1.68 14
200.98 69 LV146 38.20 1 0.56 68
200.95 69.5 LV147 22.19 1 0.55 40
200.91 70 LV148 31.82 1 0.57 56
200.88 70.5 LV149 49.15 46.82 48.0 1.2 2% 2 0.85 58
200.86 70.8 LV150 31.55 1 0.55 57
200.81 71.5 LV151 38.23 1 0.50 77
200.77 72 LV153 41.76 1 1.50 28
200.78 72.1 LV152 90.88 90.54 90.7 0.2 0% 2 0.74 123
200.74 72.55 LV154 25.32 1 0.50 50
200.73 73 LV155 32.80 1 0.50 66
200.73 73.45 LV156 31.77 1 0.49 64
200.72 74 LV157 52.82 1 1.03 51
200.71 74.4 LV158 28.84 1 0.47 61
200.71 74.9 LV159 18.79 1 1.37 14
200.70 75.5 LV160 48.73 47.01 47.9 0.6 1% 48.00 3 0.69 70
200.69 76 LV161 13.44 1 0.63 21
200.69 76.3 LV162 29.06 1 2.03 14
200.69 76.5 LV163 33.40 1 0.49 68
200.68 76.9 LV164 34.62 1 0.50 69
200.67 77.5 LV165 27.07 1 1.66 16
200.66 78.1 LV166 27.12 1 2.50 11
200.66 78.5 LV167 23.67 1 0.56 43
200.65 79 LV168 30.87 1 0.48 65
200.65 79.5 LV169 29.49 1 0.60 49
200.64 80 LV170 29.94 1 0.42 71
200.63 80.5 LV171 27.96 1 1.39 20
200.63 81 LV172 20.69 1 0.40 51
200.62 81.5 LV173 30.77 32.09 31.4 0.7 2% 2 0.60 52
293
Age Meter Sample Hg (ppb) Hg (ppb)R Average SE RSE Hg (ppb)R n %TOC Hg/TOC
200.61 82 LV174 73.33 1 0.66 112
200.61 82.5 LV175 23.5 1 0.31 75
200.61 82.5 LV176 52.6 54.8 53.7 1.1 2% 2 0.56 94
200.60 83 LV177 29.85 1 0.56 53
200.60 83 LV178A 21.41 1 0.50 43
200.60 83.25 LV178B 20.15 21.38 20.8 0.6 3% 2 1.00 20
200.59 83.5 LV179 19.82 1 0.37 54
200.59 84 LV180 19.83 1 0.88 23
200.58 84.1 LV181 73.42 1 0.68 107
200.58 84.5 LV182 51.01 47.16 49.1 1.9 4% 2 0.43 118
200.57 85.2 LV183 64.10 1 0.91 70
200.56 85.5 LV184 23.6 1 0.52 46
200.56 86 LV185 23.69 24.05 23.9 0.2 1% 2 1.27 19
200.55 86.5 LV186 63.8 67.1 65.4 1.6 2% 2 0.72 88
200.54 87 LV187 26.37 1 0.37 72
200.54 87.5 LV188 63.1 1 0.50 127
200.53 88 LV189 64.97 1 0.56 117
200.53 88.25 LV190 9.4 1 0.43 22
200.52 88.5 LV191 50.09 52.75 51.4 1.3 3% 2 0.41 121
200.52 89 LV192 56.7 1 0.44 130
200.51 89.5 LV193 58.07 1 0.38 152
200.50 90 LV194 27.6 1 0.30 91
200.50 90.5 LV195 71.22 1 0.52 138
200.49 91 LV196 34.4 34.9 34.6 0.2 1% 2 0.51 68
200.48 91.5 LV197 45.63 1 0.37 122
200.48 92 LV198 18.0 1 0.58 31
200.47 92.5 LV199 62.44 1 0.47 134
200.46 93 LV200 27.1 26.5 26.8 0.3 1% 2 0.36 75
200.46 93.3 LV201 11.5 1 0.50 23
294
Age Meter Sample Hg (ppb) Hg (ppb)R Average SE RSE Hg (ppb)R n %TOC Hg/TOC
200.46 93.5 LV202 60.7 64.5 62.6 1.9 3% 2 0.72 84
200.45 94 LV203 21.61 1 0.39 55
200.44 94.5 LV204 30.9 1 0.41 75
200.42 95 LV205 70.62 1 0.99 71
200.41 95.5 LV206 15.5 1 0.37 42
200.39 96 LV207 53.4 1 0.51 104
200.38 96.5 LV208 26.91 26.72 26.8 0.1 0% 2 0.59 46
200.36 96.9 LV209 11.0 1 0.47 23
200.35 97.5 LV210 22.8 24.0 23.4 0.6 3% 2 0.23 101
200.33 98 LV211 24.40 1 0.21 115
200.32 98.5 LV212 22.6 1 0.26 85
200.30 99 LV213 7.7 8.2 7.9 0.2 3% 2 0.16 49
200.29 99.5 LV214 10.4 10.19 2 0.43 24
200.27 100 LV215 22.3 22.3 22.3 0.0 0% 2 0.29 77
200.26 100.5 LV216 56.4 1 0.61 93
200.25 100.9 LV217 8.61 1 0.66 13
200.23 101.5 LV218 39.9 1 0.56 71
200.22 102 LV219 41.1 1 0.70 58
200.22 102 LV220 55.5 1 0.48 115
200.20 102.5 LV221 18.37 1 0.88 21
200.19 103 LV222 66.4 73.7 70.0 3.7 5% 2 0.55 120
200.17 103.5 LV223 10.6 1 0.50 21
200.16 104 LV224 41.1 40.9 41.0 0.1 0% 2 0.45 92
200.14 104.5 LV225 13.99 1 0.79 18
200.13 105 LV226 10.3 1 0.47 22
200.13 105 LV227 50.7 51.9 51.3 0.6 1% 2 0.43 118
295
I.1.2. St. Audrie's Bay, UK
meter Sample Hg (ppb) Hg (ppb)R Average SE RSE Hg (ppb)R %TOC Hg/TOC
1.2 E1 14.19 14.94 14.57 0.37 0.03 2 0.35 40.4
1.6 E2 5.64 1 0.09 61.0
3 E4 34.26 1 0.69 50.0
3.6 E5 51.23 51.77 51.50 0.27 0.01 2 0.96 53.2
3.84 E7 8.31 1 0.22 37.2
3.9 E8 53.57 1 0.82 65.1
4.4 E10 52.19 53.05 52.62 0.43 0.01 2 0.79 66.3
4.5 E11 6.42 1 0.10 65.3
4.8 E13 20.36 1 0.12 ####
5.1 E14 34.43 33.11 33.77 0.66 0.02 2 1.16 29.7
5.7 E16 27.59 1 0.55 50.1
5.85 E17 8.31 1 0.12 66.6
6.65 E19 40.66 41.85 41.25 0.60 0.01 2 7.65 5.3
6.95 E20 40.31 1 1.29 31.3
7.25 E21 37.80 2.45 15.4
7.5 E22 48.70 1.43 34.2
7.75 E23 45.50 1.23 36.9
8 E24 10.50 0.22 48.8
8.1 E25 28.30 0.61 46.4
8.5 E26 37.80 1.38 27.5
8.65 E27 31.00 0.91 34.2
8.8 E28 32.70 0.70 46.9
9.05 E29 30.90 0.89 34.8
9.3 E30 34.50 1.05 32.9
9.55 E31 30.60 0.41 73.8
9.7 E32 4.60 0.19 24.2
9.83 E33 4.60 0.14 32.4
296
meter Sample Hg (ppb) Hg (ppb)R Average SE RSE Hg (ppb)R %TOC Hg/TOC
10.1 E34 34.90 0.95 36.8
10.4 E35 39.90 0.78 50.9
10.5 E36 5.00 0.19 26.1
10.65 E37 31.60 0.80 39.3
10.8 E38 28.40 0.63 44.8
10.95 E39 33.50 1.17 28.7
11.1 E40 45.80 1.32 34.6
11.18 E41, BEEF 2.60 0.14 18.3
11.2 E41 37.60 1.20 31.4
11.3 E42 34.90 1.16 30.2
11.5 E43 35.80 1.06 33.8
11.8 ESA3B 5.20 0.06 89.4
12.2 ESA13 9.60 0.05 ####
12.6 ESA16 10.60 0.04 ####
13 ESA18 11.20 0.10 ####
13.1 ESA19 6.70 0.09 74.0
13.2 E44 30.30 0.14 ####
13.3 ESA23 16.30 0.22 74.5
13.35 E45 41.00 0.32 ####
13.8 ESA25 8.80 0.12 70.9
14.1 E46 25.60 0.50 51.6
14.3 ESA30 5.00 0.13 39.6
14.45 E47 37.50 3.47 10.8
14.5 E48 44.70 3.60 12.4
14.6 E49 42.70 2.02 21.2
14.8 E50 38.90 2.27 17.2
15.1 E51 28.40 2.21 12.8
15.35 E52 25.40 1.95 13.0
15.55 E53 26.80 3.47 7.7
297
meter Sample Hg (ppb) Hg (ppb)R Average SE RSE Hg (ppb)R %TOC Hg/TOC
15.75 E54 18.00 2.20 8.2
15.8 E55 10.60 1.49 7.1
16 E56 34.60 4.16 8.3
16.3 E57 10.10 1.29 7.8
16.52 E58 43.30 3.57 12.1
16.8 E59 91.00 9.70 9.4
17.1 E60 11.50 0.77 14.8
17.34 E61 31.40 2.83 11.1
17.4 E62 11.4 0.77 14.7
17.55 E63 9.22 0.0
17.65 E64 53.2 1 6.07 8.7
17.72 E65 65.8 72.894315 69.370544 3.5237711 0.0507964 2 7.04 9.3
19.6 E71 41.0 1 2.99 13.7
19.7 E72 50.1 1 4.06 12.3
20.1 E74 82.5 83.808929 83.138879 0.6700498 0.0080594 2 7.93 10.4
20.25 E75 128.4 1 11.80 10.9
21 E77 34.9 1 3.17 11.0
21.2 E78 39.2 37.679044 38.426166 0.747121 0.019443 2 4.91 8.0
21.9 E80 98.5 1 10.24 9.6
22.2 E81 51.1 1 4.93 10.4
22.8 E83 63.8 73.675248 68.732606 4.9426424 0.0719112 2 6.70 9.5
23.2 E84 14.4 14.372849 14.37656 0.0037117 0.0002582 2 0.38 37.4
23.7 E86 11.2 1 0.13 86.4
24 E87 41.9 41.873983 41.910027 0.0360441 0.00086 2 0.60 69.5
24.5 E89 11.5 0.16 70.5
298
I.1.3. New York Canyon, Nevada
Meters Sample Hg %TOC Hg/TOC
16.7 NYCU1 21.92 0.43 51.53
16.95 NYCU2 10.08 0.13 79.96
17.05 NYCU3 8.09 0.16 50.78
17.3 NYCU4 13.33 0.25 54.40
17.6 NYCU5 19.18 0.41 46.88
17.95 NYCU6 13.16 0.27 48.80
18.85 NYCU8 13.74 0.37 37.35
19.2 NYCU9 5.96 0.13 46.53
19.4 NYCU10 9.50 0.23 40.97
19.6 NYCU11 6.79 0.11 61.64
19.95 NYCU12 34.65 0.30 114.61
20.2 NYCU13 15.85 0.26 60.82
20.5 NYCU14 9.33 0.11 84.43
20.8 NYCU15 10.96 0.35 31.61
21.1 NYCU16 6.43 0.23 27.81
21.35 NYCU17 3.64 0.09 40.49
21.5 NYCU18 2.89 0.20 14.35
21.7 NYCU19 4.61 0.09 53.00
22 NYCU20 43.01 0.27 157.64
22.15 NYCU21 5.91 0.08 72.27
22.4 NYCU22 6.64 0.21 32.08
22.6 NYCU23 5.05 0.09 58.28
22.8 NYCU24 15.99 0.18 88.83
23.05 NYCU25 4.39 0.08 54.23
23.3 NYCU26 6.22 0.12 52.43
23.7 NYCU27 6.03 0.12 50.53
23.9 NYCU28 16.45 0.09 182.47
299
Meters Sample Hg %TOC Hg/TOC
24.1 NYCU29 11.44 0.08 140.43
24.4 NYCU30 4.46 0.10 45.87
24.7 NYCU31 4.52 0.09 50.60
24.71 NYCU32 19.53 0.08 251.09
24.95 NYCU32B 7.27 0.10 73.29
25.25 NYCU33 15.89 0.09 168.59
25.6 NYCU34 10.85 0.07 159.78
25.95 NYCU35 5.46 0.10 53.22
26.2 NYCU36 6.46 0.11 59.62
27.1 NYCU37 6.98 0.13 55.25
27.35 NYCU38 6.50 0.07 98.63
27.45 NYCU39 3.69 0.06 63.28
27.7 NYCU40 7.14 0.08 85.67
27.95 NYCU41 8.12 0.07 119.35
28.1 NYCU42 8.46 0.07 125.77
28.3 NYCU43 5.69 0.09 66.66
28.5 NYCU44 7.38 0.07 110.19
28.6 NYCU45 8.83 0.07 133.84
28.95 NYCU46 13.27 0.21 61.79
29 NYCU47 5.55 0.07 79.67
29.3 NYCU48 10.24 0.14 72.58
29.5 NYCU49 9.46 0.05 172.78
29.7 NYCU50 5.13 0.04 120.95
30 NYCU51 4.14 0.04 95.04
30.3 NYCU52 7.71 0.06 128.02
30.6 NYCU53 5.54 0.05 113.86
30.8 NYCU54 7.79 0.04 194.56
31.2 NYCU55 4.67 0.04 133.22
31.5 NYCU56 4.86 0.06 86.77
300
Meters Sample Hg %TOC Hg/TOC
31.6 NYCU57 6.00 0.20 30.50
31.95 NYCU58 2.19 0.03 63.82
32.2 NYCU59 15.96 0.24 66.40
32.5 NYCU60 11.27 0.27 41.38
33 NYCU61 14.27 0.20 71.85
33.3 NYCU62 5.14 0.05 108.93
33.5 NYCU63 5.33 0.07 76.92
33.8 NYCU64 4.79 0.10 47.66
33.95 NYCU65 6.12 0.09 65.89
34.25 NYCU66 7.67 0.09 85.90
34.4 NYCU67 5.87 0.07 89.53
34.6 NYCU68 3.97 0.05 76.60
34.83 NYCU69 4.81 0.03 141.91
35 NYCU70 5.59 0.05 113.58
35.35 NYCU71 7.85 0.04 176.70
35.7 NYCU72 4.33 0.05 83.88
36 NYCU73 4.74 0.08 61.51
36.25 NYCU74 5.29 0.07 79.56
36.5 NYCU75 9.95 0.06 164.69
36.9 NYCU76 6.81 0.05 129.88
37.2 NYCU77 10.84 0.04 243.87
37.5 NYCU78 6.20 0.04 144.70
37.7 NYCU79 2.84 0.02 121.03
38 NYCU80 2.86 0.03 85.79
38.2 NYCU81 5.61 0.05 121.68
38.4 NYCU82 3.16 0.03 92.62
301
I.2. MERCURY ISOTOPE MEASUREMENTS
I.2.1. Levanto, Peru
Sample n
δ
204
Hg
2SE
δ
202
Hg
2SE
δ
201
Hg
2SE
δ
200
Hg
2SE
δ
199
Hg
2SE
Δ
204
Hg
2SE
Δ
201
Hg
2SE
LV11 2 -0.85 0.01 -0.56 0.01 -0.40 0.00 -0.27 0.03 -0.05 0.01 -0.01 0.03 0.03 0.01
LV39 2 -0.82 0.12 -0.51 0.02 -0.34 0.02 -0.23 0.03 -0.02 0.04 -0.05 0.09 0.04 0.03
LV55 2 -0.93 0.12 -0.59 0.10 -0.40 0.04 -0.27 0.03 -0.03 0.06 -0.05 0.02 0.04 0.03
LV70 2 -1.82 0.25 -1.19 0.10 -0.87 0.02 -0.60 0.05 -0.23 0.00 -0.05 0.10 0.02 0.05
LV88 2 -0.99 0.02 -0.62 0.03 -0.48 0.03 -0.30 0.03 -0.10 0.02 -0.06 0.01 -0.01 0.02
LV93 2 -0.44 0.07 -0.30 0.06 -0.17 0.06 -0.14 0.04 0.02 0.04 0.00 0.02 0.05 0.01
LV108 2 -0.50 0.03 -0.32 0.04 -0.22 0.03 -0.15 0.02 -0.02 0.02 -0.02 0.03 0.02 0.00
LV111 2 -0.67 0.24 -0.44 0.18 -0.34 0.09 -0.19 0.07 -0.07 0.00 -0.02 0.03 -0.02 0.04
LV113 2 -1.29 0.04 -0.84 0.01 -0.62 0.01 -0.39 0.03 -0.15 0.01 -0.03 0.04 0.01 0.00
LV117 2 -0.80 0.37 -0.52 0.22 -0.43 0.17 -0.25 0.12 -0.13 0.05 -0.02 0.04 -0.03 0.01
LV122 2 -1.72 0.35 -1.14 0.20 -0.91 0.14 -0.55 0.11 -0.31 0.04 -0.02 0.05 -0.05 0.02
LV123 2 -2.15 0.18 -1.43 0.08 -1.08 0.04 -0.69 0.03 -0.32 0.00 -0.02 0.06 -0.01 0.03
LV127 2 -1.42 0.01 -0.93 0.00 -0.76 0.01 -0.45 0.01 -0.28 0.03 -0.02 0.01 -0.06 0.01
LV135 2 -1.63 0.03 -1.09 0.00 -0.88 0.00 -0.52 0.00 -0.29 0.00 0.00 0.02 -0.06 0.00
LV139 2 -1.40 0.06 -0.93 0.03 -0.78 0.04 -0.46 0.01 -0.29 0.01 -0.01 0.02 -0.08 0.02
LV168 2 -1.23 0.05 -0.83 0.00 -0.69 0.02 -0.41 0.00 -0.22 0.01 0.01 0.06 -0.07 0.02
LV182 2 -1.36 0.16 -0.92 0.09 -0.71 0.08 -0.45 0.04 -0.24 0.00 0.01 0.02 -0.02 0.01
LV182 dup 2 -1.53 0.13 -1.03 0.02 -0.82 0.00 -0.52 0.03 -0.25 0.01 0.00 0.10 -0.05 0.01
LV183 2 -1.23 0.25 -0.84 0.16 -0.65 0.11 -0.41 0.08 -0.20 0.01 0.03 0.00 -0.02 0.01
LV183 dup 2 -1.14 0.59 -0.75 0.38 -0.61 0.24 -0.39 0.19 -0.19 0.04 -0.02 0.03 -0.05 0.04
LV205 2 -0.88 0.07 -0.59 0.02 -0.47 0.02 -0.30 0.02 -0.11 0.00 0.01 0.03 -0.02 0.01
302
Sample n
Δ
200
Hg
2SE
Δ
199
Hg
2SE
LV11 2 0.01 0.02 0.09 0.01
LV39 2 0.02 0.04 0.11 0.05
LV55 2 0.02 0.02 0.12 0.04
LV70 2 -0.01 0.00 0.07 0.03
LV88 2 0.01 0.02 0.05 0.02
LV93 2 0.01 0.01 0.10 0.02
LV108 2 0.02 0.00 0.06 0.01
LV111 2 0.03 0.02 0.04 0.04
LV113 2 0.03 0.02 0.06 0.01
LV117 2 0.01 0.02 0.00 0.01
LV122 2 0.02 0.01 -0.02 0.01
LV123 2 0.02 0.02 0.04 0.02
LV127 2 0.02 0.01 -0.04 0.03
LV135 2 0.03 0.00 -0.01 0.00
LV139 2 0.00 0.01 -0.06 0.01
LV168 2 0.01 0.00 -0.01 0.01
LV182 2 0.01 0.01 -0.01 0.02
LV182 dup 2 0.00 0.02 0.01 0.01
LV183 2 0.01 0.01 0.02 0.03
LV183 dup 2 -0.01 0.00 0.00 0.06
LV205 2 0.00 0.00 0.04 0.01
303
I.2.2. St. Audrie's Bay, UK
Sample ID n
δ
204
Hg
2SE
δ
202
Hg
2SE
δ
201
Hg
2SE
δ
200
Hg
2SE
δ
199
Hg
2SE
Δ
204
Hg
2SE
Δ
201
Hg
2SE
E4 2 -1.89 0.13 -1.23 0.07 -1.28 0.05 -0.60 0.05 -0.55 0.01 -0.06 0.03 -0.36 0.00
E10 2 -1.54 0.63 -1.01 0.38 -1.13 0.23 -0.50 0.12 -0.52 0.03 -0.03 0.07 -0.37 0.05
E14 2 -1.89 0.56 -1.22 0.37 -1.32 0.22 -0.56 0.16 -0.61 0.00 -0.08 0.02 -0.40 0.05
E20 2 -1.65 0.21 -1.08 0.14 -1.22 0.08 -0.53 0.08 -0.57 0.03 -0.04 0.01 -0.41 0.03
E34 2 -1.57 0.36 -1.03 0.20 -1.25 0.10 -0.50 0.06 -0.72 0.00 -0.03 0.07 -0.47 0.04
ESA3B 2 -2.41 0.03 -1.62 0.05 -1.42 0.01 -0.82 0.01 -0.56 0.04 0.01 0.04 -0.20 0.04
ESA18 2 -1.21 0.54 -0.81 0.38 -0.73 0.29 -0.43 0.19 -0.27 0.04 0.00 0.03 -0.12 0.00
ESA19 2 -1.25 0.09 -0.85 0.09 -0.80 0.08 -0.45 0.05 -0.38 0.01 0.02 0.04 -0.16 0.01
E45 2 -1.98 0.04 -1.34 0.02 -1.15 0.02 -0.69 0.01 -0.41 0.02 0.02 0.02 -0.14 0.03
E59 2 -1.08 0.53 -0.74 0.38 -0.87 0.23 -0.41 0.18 -0.55 0.04 0.03 0.04 -0.32 0.06
E65 2 -1.34 0.23 -0.89 0.15 -0.99 0.07 -0.47 0.07 -0.54 0.00 -0.01 0.00 -0.33 0.04
E75 2 -1.15 0.02 -0.78 0.04 -0.89 0.01 -0.40 0.01 -0.50 0.02 0.02 0.04 -0.30 0.02
E83 2 -1.47 0.42 -1.00 0.26 -1.03 0.19 -0.51 0.12 -0.55 0.00 0.01 0.03 -0.28 0.00
E87 2 -1.68 0.20 -1.15 0.11 -1.23 0.01 -0.61 0.03 -0.65 0.04 0.03 0.04 -0.37 0.07
304
Sample ID n
Δ
200
Hg
2SE
Δ
199
Hg
2SE
E4 2 0.02 0.02 -0.24 0.00
E10 2 0.01 0.07 -0.27 0.13
E14 2 0.05 0.03 -0.30 0.09
E20 2 0.01 0.00 -0.30 0.01
E34 2 0.02 0.04 -0.46 0.05
ESA3B 2 0.00 0.03 -0.16 0.05
ESA18 2 -0.02 0.00 -0.07 0.06
ESA19 2 -0.02 0.01 -0.17 0.01
E45 2 -0.02 0.01 -0.08 0.02
E59 2 -0.04 0.01 -0.36 0.06
E65 2 -0.02 0.00 -0.32 0.04
E75 2 -0.01 0.03 -0.30 0.03
E83 2 -0.01 0.01 -0.30 0.06
E87 2 -0.03 0.02 -0.36 0.07
305
I.3. MERCURY ISOTOPE STANDARDS
Sample ID n
δ
204
Hg
2σ
δ
202
Hg
2σ
δ
201
Hg
2σ
δ
200
Hg
2σ
NIST 3133 Session 0 (Nov 2015) 2 -0.02 0.09 -0.03 0.06 -0.02 0.04 -0.02 0.04
Average NIST 3133 (sessions 1-6) 11 -0.05 0.11 -0.04 0.08 -0.03 0.09 -0.02 0.06
NIST 1646A Session 0 (Nov 2015) 2 -1.42 0.01 -0.95 0.03 -0.67 0.02 -0.44 0.01
Average NIST 1646a (sessions 1-6) 3 -1.48 0.11 -0.98 0.08 -0.71 0.09 -0.46 0.06
JTBaker Session 0 (Nov 2015) 7 -0.86 0.12 -0.58 0.10 -0.44 0.05 -0.29 0.04
JTBaker Session 1 (Aug 24 2016) 7 -0.83 0.42 -0.53 0.29 -0.42 0.21 -0.26 0.15
JTBaker Session 2 (Oct 20 2016) 5 -0.97 0.31 -0.65 0.20 -0.48 0.14 -0.32 0.12
JTBaker Session 3 (Oct 21 2016) 4 -0.89 0.37 -0.63 0.31 -0.48 0.19 -0.38 0.19
JTBaker Session 4 (Jan 18 2017) 9 -0.77 0.29 -0.52 0.20 -0.41 0.12 -0.27 0.09
JTBaker Session 5 (Jan 19 2017a) 7 -0.88 0.13 -0.64 0.19 -0.43 0.04 -0.26 0.05
JTBaker Session 6 (Jan 19 2017b) 3 -1.05 0.20 -0.69 0.09 -0.52 0.07 -0.34 0.04
NIST 1944 (sessions 1-6) 9 -0.7 0.11 -0.46 0.08 -0.36 0.09 -0.22 0.06
NIST 1575a (sessions 1-6) 3 -1.74 0.12 -1.13 0.08 -1.27 0.09 -0.55 0.06
CCRMP TILL-1 (sessions 1-6) 4 -1.52 0.2 -1 0.14 -0.89 0.1 -0.49 0.06
306
Sample ID n
δ
199
Hg
2σ
Δ
204
Hg
2σ
Δ
201
Hg
2σ
Δ
200
Hg
2σ
Δ
199
Hg
2σ
NIST 3133 Session 0 (Nov 2015) 2 0.00 0.00 0.02 0.00 0.00 0.01 -0.01 0.01 0.00 0.01
Average NIST 3133 (sessions 1-6) 11 0.00 0.05 0.00 0.06 0.00 0.05 0.00 0.03 0.01 0.04
NIST 1646A Session 0 (Nov 2015) 2 -0.15 0.02 -0.01 0.02 0.04 0.00 0.03 0.01 0.08 0.02
Average NIST 1646a (sessions 1-6) 3 -0.17 0.05 -0.03 0.06 0.03 0.05 0.03 0.03 0.08 0.04
JTBaker Session 0 (Nov 2015) 7 -0.14 0.05 0.00 0.02 -0.01 0.02 0.01 0.01 0.01 0.02
JTBaker Session 1 (Aug 24 2016) 7 -0.12 0.05 -0.03 0.07 -0.02 0.04 0.00 0.03 0.01 0.06
JTBaker Session 2 (Oct 20 2016) 5 -0.14 0.09 0.00 0.09 0.00 0.04 0.01 0.04 0.02 0.06
JTBaker Session 3 (Oct 21 2016) 4 -0.16 0.08 0.05 0.18 -0.01 0.12 -0.06 0.09 0.00 0.07
JTBaker Session 4 (Jan 18 2017) 9 -0.13 0.04 0.01 0.02 -0.02 0.04 -0.01 0.01 0.00 0.02
JTBaker Session 5 (Jan 19 2017a) 7 -0.12 0.05 -0.02 0.04 0.00 0.03 0.03 0.03 0.03 0.03
JTBaker Session 6 (Jan 19 2017b) 3 -0.16 0.02 -0.02 0.08 0.00 0.01 0.01 0.01 0.02 0.00
NIST 1944 (sessions 1-6) 9 -0.11 0.05 -0.02 0.06 -0.02 0.05 0.01 0.03 0.01 0.04
NIST 1575a (sessions 1-6) 3 -0.63 0.05 -0.05 0.06 -0.42 0.05 0.02 0.03 -0.34 0.04
CCRMP TILL-1 (sessions 1-6) 4 -0.37 0.05 -0.02 0.06 -0.14 0.05 0.01 0.03 -0.12 0.04
307
Appendix J. Sponge spicule silicon isotope data (dataset from Chapter 5)
note: Preservation includes: small brown, large brown, clear spicules, red rind; see SI figures for example of preservation types and analysis notes
note: SD(S) refers to the standard deviation of the bracketing standard of this analysis; SD(A) refers to standard deviation of the analysis.
note:analyses with SD(A)>0.25 have been removed
J.1. LEV ANTO, PERU
Sample Spicule # δ30Si SD(S) SD(A) Preservation Note 1 Note 2 (if need be) Note 3 (if need be)
LV17 2 -3.49 0.96 0.15 clear partially intersects matrix
LV17 2 -1.11 0.96 0.15 clear partially intersects matrix
LV17 2 -1.29 0.96 0.16 clear partially intersects matrix
LV17 3 -1.49 0.96 0.12 clear centered on spicule intersects axial filament partially intersects matrix
LV17 3 -1.95 0.96 0.12 clear centered on spicule intersects axial filament partially intersects matrix
LV17 4 -1.72 0.96 0.12 clear centered on spicule intersects axial filament partially intersects matrix
LV17 4 -1.93 0.96 0.14 clear centered on spicule partially intersects matrix
LV17 5 -1.87 0.96 0.16 unclear
LV17 5 -1.04 0.96 0.25 clear centered on spicule intersects axial filament
LV17 6 -1.05 0.63 0.15 small brown centered on spicule
LV17 6 -1.17 0.63 0.18 small brown centered on spicule
LV17 6 -0.91 0.63 0.18 small brown centered on spicule
LV17 6 -0.22 0.63 0.21 small brown partially intersects matrix
LV17 8 -0.16 0.63 0.12 clear centered on spicule
LV17 8 -0.08 0.63 0.13 clear centered on spicule
LV17 8 -0.24 0.63 0.19 clear centered on spicule
LV17 8 0.08 0.63 0.24 clear centered on spicule intersects axial filament
LV17 8 -1.65 0.63 0.25 clear centered on spicule intersects axial filament
LV17 10 -1.81 0.63 0.10 small brown centered on spicule partially intersects matrix intersects axial filament
308
Sample Spicule # δ30Si SD(S) SD(A) Preservation Note 1 Note 2 (if need be) Note 3 (if need be)
LV17 10 -2.53 0.63 0.16 small brown centered on spicule partially intersects matrix intersects axial filament
LV17 10 -0.01 0.63 0.16 small brown centered on spicule partially intersects matrix
LV17 11 -2.83 0.63 0.11
LV17 11 -2.20 0.63 0.13 clear partially intersects matrix
LV17 11 -2.63 0.63 0.13 clear partially intersects matrix intersects axial filament
LV17 11 -2.19 0.63 0.22 clear centered on spicule partially intersects matrix
LV17 12 -0.21 0.29 0.18 small brown centered on spicule intersects axial filament
LV17 12 -0.34 0.29 0.20 small brown centered on spicule intersects axial filament
LV17 12 1.38 0.29 0.22 small brown centered on spicule intersects axial filament
LV17 12 -0.68 0.29 0.24 small brown centered on spicule intersects axial filament
LV17 13 0.02 0.29 0.14 small brown centered on spicule intersects axial filament
LV17 13 -0.41 0.29 0.17 small brown centered on spicule intersects axial filament
LV17 13 -0.19 0.29 0.20 small brown centered on spicule intersects axial filament
LV17 13 0.72 0.29 0.22 small brown centered on spicule intersects axial filament
LV17 13 0.83 0.29 0.24 small brown centered on spicule intersects axial filament
LV17 14 1.00 0.29 0.18 clear centered on spicule
LV17 14 -0.66 0.29 0.19 clear centered on spicule
LV17 15 -1.44 0.29 0.16 small brown centered on spicule
LV17 15 -0.68 0.29 0.20 small brown centered on spicule
LV17 15 -0.71 0.29 0.22 small brown centered on spicule
LV17 15 -0.71 0.29 0.22 small brown centered on spicule
LV17 15 -0.68 0.29 0.23 small brown centered on spicule
LV17 16 -2.02 0.27 0.13 clear centered on spicule
LV17 16 -1.63 0.27 0.13 clear centered on spicule intersects axial filament
LV17 16 -2.35 0.27 0.14 clear centered on spicule intersects axial filament
LV17 16 -1.79 0.27 0.16 clear centered on spicule intersects axial filament
LV17 17 0.07 0.27 0.13 small brown centered on spicule
LV17 17 -0.89 0.27 0.14 small brown centered on spicule
LV17 17 0.33 0.27 0.17 small brown centered on spicule
309
Sample Spicule # δ30Si SD(S) SD(A) Preservation Note 1 Note 2 (if need be) Note 3 (if need be)
LV17 17 0.27 0.27 0.21 small brown centered on spicule
LV17 17 0.89 0.27 0.25 small brown centered on spicule
LV17 18 -0.56 0.27 0.23 small brown centered on spicule intersects axial filament
LV17 sp18 -0.47 0.27 0.10 small brown centered on spicule intersects axial filament
LV17 sp18 0.12 0.27 0.14 unclear
LV49 1 -1.54 0.53 0.11 small brown centered on spicule intersects axial filament
LV49 1 -1.26 0.53 0.12 clear centered on spicule intersects axial filament
LV49 1 -0.38 0.53 0.13 clear centered on spicule intersects axial filament
LV49 1 -1.44 0.53 0.14 clear centered on spicule intersects axial filament
LV49 1 -1.79 0.53 0.14 small brown unclear
LV49 1 -0.91 0.53 0.14 clear centered on spicule intersects axial filament
LV49 1 -0.86 0.53 0.14 clear centered on spicule intersects axial filament
LV49 1 -0.91 0.53 0.15 small brown centered on spicule intersects axial filament
LV49 1 -1.35 0.53 0.15 clear centered on spicule intersects axial filament
LV49 1 -1.69 0.53 0.17 small brown unclear
LV49 1 -1.11 0.53 0.17 clear centered on spicule intersects axial filament
LV49 1 -1.42 0.53 0.19 unclear
LV49 1 -1.64 0.53 0.20 clear centered on spicule intersects axial filament
LV49 1 -0.64 0.53 0.20 small brown centered on spicule intersects axial filament
LV49 1 -0.52 0.53 0.21 clear centered on spicule intersects axial filament
LV49 1 -1.36 0.53 0.21 clear centered on spicule intersects axial filament
LV49 1 -2.31 0.53 0.22 small brown unclear
LV49 1 -1.96 0.53 0.24 clear centered on spicule intersects axial filament
LV49 1 -1.00 0.53 0.25 clear centered on spicule intersects axial filament
LV49 2 -1.91 0.50 0.15 unclear
LV49 2 -0.98 0.50 0.17 unclear
LV49 2 -1.59 0.50 0.17 unclear
LV49 2 -2.28 0.50 0.18 unclear
LV49 2 -1.92 0.50 0.21 unclear
310
Sample Spicule # δ30Si SD(S) SD(A) Preservation Note 1 Note 2 (if need be) Note 3 (if need be)
LV49 3 -1.19 0.50 0.16 clear centered on spicule partially intersects matrix
LV49 3 -1.91 0.50 0.17 clear centered on spicule intersects axial filament
LV49 3 -0.92 0.50 0.18 clear centered on spicule intersects axial filament
LV49 4 -0.64 0.50 0.14 clear centered on spicule intersects axial filament
LV49 4 -0.83 0.50 0.14 clear centered on spicule intersects axial filament
LV49 5 -1.08 0.50 0.13 small brown centered on spicule intersects axial filament
LV49 5 -1.83 0.50 0.15 small brown centered on spicule
LV49 5 -1.63 0.50 0.18 small brown centered on spicule
LV49 6 -1.67 0.50 0.15 large brown centered on spicule intersects axial filament
LV49 6 -0.09 0.50 0.15 large brown centered on spicule intersects axial filament
LV49 6 -1.54 0.50 0.17 large brown centered on spicule intersects axial filament
LV78 1 -0.10 0.29 0.11 small brown centered on spicule
LV78 1 -0.53 0.29 0.13 small brown centered on spicule intersects axial filament
LV78 1 0.00 0.29 0.14 small brown centered on spicule
LV78 1 -0.22 0.29 0.15 unclear unclear
LV78 1 0.06 0.29 0.15 small brown centered on spicule
LV78 1 1.01 0.29 0.16 small brown centered on spicule intersects axial filament
LV78 1 0.06 0.29 0.17 unclear unclear
LV78 1 -0.09 0.29 0.17 small brown centered on spicule
LV78 1 -0.75 0.29 0.17 small brown unclear
LV78 1 -0.12 0.29 0.19 small brown unclear
LV78 1 -0.09 0.29 0.22 small brown centered on spicule
LV78 1 -0.01 0.29 0.23 small brown centered on spicule partially intersects matrix partially intersects matrix
LV78 2 -1.60 0.07 0.09 clear centered on spicule intersects axial filament
LV78 2 -0.22 0.07 0.12 clear centered on spicule partially intersects matrix partially intersects matrix
LV78 2 -1.95 0.07 0.13 clear centered on spicule intersects axial filament partially intersects matrix
LV78 2 -0.42 0.32 0.14 clear centered on spicule intersects axial filament
LV78 2 -1.67 0.07 0.19 clear centered on spicule intersects axial filament partially intersects matrix
LV78 2 -0.74 0.07 0.21 clear centered on spicule intersects axial filament
311
Sample Spicule # δ30Si SD(S) SD(A) Preservation Note 1 Note 2 (if need be) Note 3 (if need be)
LV78 2 -0.89 0.07 0.21 clear centered on spicule intersects axial filament
LV78 2 -1.36 0.07 0.25 clear centered on spicule intersects axial filament
LV78 3 0.59 0.07 0.17 small brown centered on spicule intersects axial filament
LV78 3 0.31 0.07 0.17 small brown centered on spicule intersects axial filament
LV78 3 0.42 0.07 0.22 small brown centered on spicule intersects axial filament
LV78 4 -0.82 0.55 0.11 clear centered on spicule
LV78 4 -0.77 0.55 0.13 clear centered on spicule
LV78 4 -0.81 0.55 0.15 clear centered on spicule partially intersects matrix
LV78 4 -0.34 0.55 0.15 clear centered on spicule
LV78 4 -1.20 0.55 0.15 clear centered on spicule
LV78 4 -1.23 0.55 0.15 clear centered on spicule
LV78 4 -0.69 0.55 0.16 clear centered on spicule
LV78 4 -1.70 0.55 0.17 clear centered on spicule
LV78 4 -1.11 0.55 0.17 clear centered on spicule
LV78 4 -0.73 0.55 0.21 clear centered on spicule partially intersects matrix
LV78 4 -0.75 0.55 0.22 clear centered on spicule
LV78 4 -0.68 0.55 0.23 clear centered on spicule partially intersects matrix
LV78 4 -0.86 0.55 0.23 clear centered on spicule
LV78 6 0.09 0.30 0.12 clear centered on spicule intersects axial filament
LV78 6 0.13 0.30 0.16 clear centered on spicule
LV78 6 0.40 0.30 0.16 clear centered on spicule
LV78 6 -0.11 0.30 0.18 clear centered on spicule
LV78 6 -0.09 0.30 0.19 clear unclear
LV78 6 -0.56 0.30 0.20 clear unclear
LV78 6 0.03 0.30 0.24 clear centered on spicule
LV78 6 0.43 0.30 0.24 clear unclear
LV78 8 0.04 0.33 0.11 clear centered on spicule intersects axial filament
LV78 8 -0.23 0.33 0.12 unclear unclear
LV78 8 0.43 0.33 0.14 unclear unclear
312
Sample Spicule # δ30Si SD(S) SD(A) Preservation Note 1 Note 2 (if need be) Note 3 (if need be)
LV78 8 0.33 0.33 0.15 clear centered on spicule
LV78 8 0.35 0.33 0.16 unclear unclear
LV78 8 0.11 0.33 0.19 unclear centered on spicule partially intersects matrix
LV78 8 -0.65 0.33 0.20 clear centered on spicule intersects axial filament
LV78 5a -1.63 0.55 0.13 clear centered on spicule intersects axial filament
LV78 5a -0.52 0.55 0.15 clear centered on spicule
LV78 5a -1.56 0.55 0.15 clear centered on spicule intersects axial filament
LV78 5b -0.06 0.55 0.12 clear centered on spicule
LV78 5b -0.38 0.55 0.16 clear centered on spicule
LV78 5b 0.52 0.55 0.16 clear centered on spicule
LV78 5b 0.12 0.55 0.17 clear centered on spicule intersects axial filament
LV78 5b 0.63 0.55 0.17 clear centered on spicule
LV78 5b 0.03 0.55 0.18 clear centered on spicule
LV78 5b 0.69 0.55 0.19 clear centered on spicule partially intersects matrix
LV78 5b 0.18 0.55 0.19 clear centered on spicule
LV149 1 1.64 0.83 0.14 small brown intersects axial filament
LV149 1 1.62 0.83 0.14 small brown centered on spicule
LV149 1 2.83 0.83 0.16 small brown centered on spicule
LV149 1 3.09 0.83 0.20 small brown intersects axial filament
LV149 2 0.57 0.83 0.21 small brown centered on spicule
LV149 2 0.86 0.83 0.22 small brown centered on spicule
LV149 2 0.65 0.83 0.22 small brown centered on spicule
LV149 2 0.45 0.83 0.23 small brown intersects axial filament
LV149 3 -0.06 0.83 0.18 small brown centered on spicule
LV149 3 -0.35 0.83 0.21 small brown centered on spicule
LV149 3 1.48 0.83 0.24 small brown centered on spicule
LV149 3 0.35 0.83 0.25 small brown centered on spicule
LV149 4 0.04 0.83 0.19 small brown? centered on spicule
LV149 4 -0.26 0.83 0.21 unclear unclear
313
Sample Spicule # δ30Si SD(S) SD(A) Preservation Note 1 Note 2 (if need be) Note 3 (if need be)
LV149 4 0.34 0.83 0.21 small brown centered on spicule
LV149 4 -0.60 0.83 0.23 unclear unclear
LV149 5 0.36 0.63 0.11 small brown centered on spicule
LV149 5 0.24 0.63 0.12 small brown centered on spicule
LV149 5 1.13 0.63 0.14 small brown centered on spicule
LV149 5 0.25 0.63 0.16 small brown centered on spicule
LV149 5 0.33 0.63 0.17 small brown centered on spicule
LV149 7 -0.24 0.63 0.13 small brown intersects axial filament partially intersects matrix
LV149 7 -1.18 0.63 0.20 small brown unclear
LV149 8 0.96 0.63 0.19 large brown centered on spicule
LV149 8 2.08 0.63 0.20 large brown centered on spicule
LV149 9 -0.12 0.63 0.15 small brown centered on spicule
LV149 9 0.67 0.63 0.19 small brown centered on spicule
LV149 9 0.26 0.63 0.20 small brown centered on spicule
LV149 11 0.72 0.63 0.14 small brown centered on spicule
LV149 11 0.26 0.63 0.15 small brown centered on spicule
LV149 11 0.66 0.63 0.15 small brown centered on spicule partially intersects matrix
LV149 11 0.21 0.63 0.20 small brown? unclear
LV149 13 -0.01 0.70 0.13 small brown centered on spicule
LV149 13 0.62 0.70 0.14 small brown centered on spicule
LV149 13 0.01 0.70 0.16 small brown centered on spicule
LV149 13 -0.76 0.70 0.17 small brown centered on spicule
LV149 13 -0.52 0.70 0.18 small brown centered on spicule
LV149 13 -0.36 0.70 0.19 small brown centered on spicule
LV149 13 0.44 0.70 0.19 small brown centered on spicule
LV149 13 -0.43 0.70 0.20 small brown centered on spicule
LV149 13 -0.64 0.70 0.23 small brown centered on spicule
LV149 13 0.15 0.70 0.24 small brown centered on spicule
LV149 14 0.68 0.70 0.14 small brown centered on spicule
314
Sample Spicule # δ30Si SD(S) SD(A) Preservation Note 1 Note 2 (if need be) Note 3 (if need be)
LV149 14 0.26 0.70 0.17 small brown centered on spicule
LV149 14 0.30 0.70 0.17 small brown centered on spicule
LV149 15 -1.63 0.70 0.19 unclear unclear
LV149 15 -0.83 0.70 0.21 unclear unclear
LV149 15 -0.23 0.70 0.22 small brown partially intersects matrix
LV149 16 1.00 0.55 0.13 small brown centered on spicule
LV149 16 0.94 0.55 0.15 unclear partially intersects matrix
LV149 16 0.39 0.55 0.18 unclear unclear
LV149 16 0.54 0.55 0.19 small brown centered on spicule
LV149 16 1.06 0.55 0.19 small brown centered on spicule
LV149 18 0.57 0.48 0.12 small brown centered on spicule intersects axial filament
LV149 18 0.50 0.48 0.14 small brown centered on spicule
LV149 18 1.48 0.48 0.18 small brown centered on spicule intersects axial filament
LV149 18 1.02 0.48 0.19 small brown centered on spicule intersects axial filament
LV149 18 0.51 0.48 0.20 small brown centered on spicule intersects axial filament
LV149 18 0.00 0.48 0.21 small brown centered on spicule
LV149 19 0.53 0.48 0.13 small brown centered on spicule
LV149 19 1.31 0.48 0.14 small brown centered on spicule
LV149 19 0.04 0.48 0.17 small brown centered on spicule intersects axial filament
LV149 19 0.50 0.48 0.19 small brown centered on spicule
LV149 19 0.35 0.48 0.19 small brown centered on spicule
LV149 20 0.55 0.48 0.13 small brown centered on spicule
LV149 20 0.36 0.48 0.14 small brown centered on spicule
LV149 20 0.33 0.48 0.14 small brown centered on spicule intersects axial filament
LV149 20 1.24 0.48 0.17 small brown centered on spicule
LV149 20 0.28 0.48 0.17 small brown centered on spicule
LV149 20 0.21 0.48 0.20 small brown centered on spicule
LV149 21 0.59 0.60 0.13 small brown centered on spicule
LV149 21 0.44 0.60 0.13 small brown centered on spicule
315
Sample Spicule # δ30Si SD(S) SD(A) Preservation Note 1 Note 2 (if need be) Note 3 (if need be)
LV149 21 0.23 0.60 0.17 unclear unclear
LV149 22 0.47 0.60 0.09 small brown intersects axial filament partially intersects matrix
LV149 22 0.61 0.60 0.21 small brown intersects axial filament partially intersects matrix
LV149 23 0.54 0.60 0.15 small brown centered on spicule
LV149 23 0.11 0.60 0.16 small brown centered on spicule
LV149 23 -0.20 0.60 0.17 small brown centered on spicule
LV149 17a 1.20 0.55 0.13 small brown centered on spicule
LV149 17a 1.27 0.55 0.14 small brown centered on spicule intersects axial filament
LV149 17a 0.17 0.55 0.19 small brown centered on spicule
LV149 17b 0.21 0.55 0.12 small brown centered on spicule
LV149 17b 0.43 0.55 0.13 small brown centered on spicule
LV149 17b 0.92 0.55 0.15 small brown centered on spicule
LV149 17b 0.17 0.55 0.15 small brown centered on spicule
LV149 17b 0.72 0.55 0.22 small brown centered on spicule
LV149 17b 0.16 0.55 0.22 small brown centered on spicule
LV149 17c 0.94 0.55 0.19 large brown centered on spicule intersects axial filament
316
J.2. MALPASO, PERU
Sample δ30Si SD(S) SD(A)
M06 1.32 0.76 0.16
M06 -0.52 0.76 0.19
M06 0.27 0.76 0.18
M06 0.04 0.76 0.20
M06 -0.70 0.76 0.31
M06 -0.78 0.76 0.15
M06 -1.24 0.76 0.14
M06 -1.20 0.76 0.13
M06 -1.54 0.76 0.15
M06 -0.85 0.76 0.19
M06 -1.47 0.76 0.13
M06 -1.20 0.76 0.16
M06 -0.83 0.76 0.13
M06 -1.97 0.76 0.21
M06 -1.68 0.76 0.16
M06 -0.05 0.76 0.16
M06 -1.85 0.76 0.18
M06 -1.83 0.76 0.23
M06 -1.62 0.76 0.17
M06 -1.75 0.76 0.20
M06 -0.98 0.76 0.20
M06 -1.42 0.76 0.16
M06 -1.62 0.76 0.14
M06 -0.94 0.76 0.16
M06 -0.91 0.76 0.17
M06 -1.35 0.76 0.16
M06 -1.50 0.76 0.17
M06 -1.62 0.76 0.21
M06 -1.59 0.76 0.16
M06 -1.21 0.76 0.15
M06 -0.49 0.76 0.20
M06 -0.42 0.76 0.19
M06 -0.98 0.76 0.20
M06 -1.64 0.75 0.25
M06 -1.53 0.75 0.16
M06 -1.68 0.75 0.17
M06 -1.44 0.75 0.13
M06 -1.56 0.75 0.17
M06 -1.07 0.75 0.22
M06 -1.62 0.75 0.12
M06 -2.03 0.75 0.16
M06 -1.20 0.75 0.13
M06 -1.94 0.75 0.14
MP4 -0.92 0.40 0.21
MP4 0.07 0.40 0.16
MP4 0.18 0.40 0.23
MP4 -0.81 0.40 0.21
MP4 0.06 0.40 0.21
MP4 0.73 0.40 0.20
MP4 -0.57 0.40 0.13
MP4 0.16 0.40 0.18
MP4 -0.47 0.40 0.20
MP4 -0.25 0.40 0.17
MP4 -0.24 0.40 0.19
MP4 -0.05 0.40 0.20
317

Abstract (if available)

Abstract The end-Triassic mass extinction (ETE

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University of Southern California Dissertations and Theses

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Asset Metadata

Creator Yager, Joyce Ann (author)

Core Title Sedimentary geochemistry associated with the end-Triassic mass extinction: changes to the marine environment from an age constrained sedimentary section

School College of Letters, Arts and Sciences

Degree Doctor of Philosophy

Degree Program Geological Sciences

Publication Date 12/21/2020

Defense Date 03/06/2019

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag anoxia,carbon isotopes,Central Atlantic magmatic province,End-Triassic extinction,mercury concentrations,mercury isotopes,nitrogen isotopes,OAI-PMH Harvest,redox,silicon isotopes,trace metals,Triassic-Jurassic boundary

Format application/pdf (imt)

Language English

Contributor Electronically uploaded by the author (provenance)

Advisor Bottjer, David J. (committee chair), Berelson, William M. (committee member), Corsetti, Frank A. (committee member), Levine, Naomi M. (committee member), West, A. Joshua (committee member)

Creator Email joyceannyager@gmail.com,joyceyag@usc.edu

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c89-177800

Unique identifier UC11662231

Identifier etd-YagerJoyce-7508.pdf (filename),usctheses-c89-177800 (legacy record id)

Legacy Identifier etd-YagerJoyce-7508.pdf

Dmrecord 177800

Document Type Dissertation

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Rights Yager, Joyce Ann

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the a...

Repository Name University of Southern California Digital Library

Repository Location USC Digital Library, University of Southern California, University Park Campus MC 2810, 3434 South Grand Avenue, 2nd Floor, Los Angeles, California 90089-2810, USA