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Kinematic history and tectonic implications of the Kokoweef-Slaughterhouse fault, eastern Mojave desert, California

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Kinematic history and tectonic implications of the Kokoweef-Slaughterhouse fault, eastern Mojave desert, California

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KINEMATIC HISTORY AND TECTONIC IMPLICATIONS
OF THE KOKOWEEF-SLAUGHTERHOUSE FAULT,
EASTERN MOJAVE DESERT, CALIFORNIA
Jacob Brooks Ramsdell
A Thesis Presented to the
FACULTY OF THE GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree of
MASTER OF SCIENCE
(Geological Sciences)
May 1999
Copyright 1999 Jacob Brooks Ramsdell
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UMI Number: 1395141
Copyright 1999 by
Ramsdell, Jacob Brooks
All rights reserved.
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U N IV E R S IT Y O F S O U T H E R N C A L IF O R N IA
t h e g r a d u a t e s c h o o l
U N IV ER SITY HARK
LOS A N O ELES. C A L IF O R N IA > 0 0 0 7
Thit thesis, written by
J a c o b B ro o k s Ra m sde l l _____ ___ _ __ ___
under the direction of A ia Thesis Committee,
and approved by all its members, has been pre~
seated to and accepted by the Dean of The
Graduate School, in partial fulfillment of the
requirements for the degree of
THESIS^COMMITTEE
a .
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ACKNOWLEDGEMENTS
I gratefully acknowledge the following people: my advisor, Greg
Davis, for introducing me to the perplexities of the Kokoweef-
Slaughterhouse fault, and for his patience while I grappled with them; my
other committee members, Scott Paterson and Charlie Sammis, for their
comments and support; my fellow students, Brian Darby, Cong Wang and
the entire strain lab crew, for their friendship and support. I would also like
to thank my wife, Rosa, for her love and willingness to dance in the garden
and float on a zephyr's song. I also thank my family for their love and
support.
This research was supported by monies from the Graduate Student
Research Fund and the Shackelford Fund.
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TABLE OF CONTENTS
ACKNOWLEDGEMENTS......................................................................................ii
LIST OF FIGURES....................................................................................................v
LIST OF PLATES......................................................................................................vi
ABSTRACT................................................................................................................viii
Chapter 1: INTRODUCTION................................................................................ 1
General introduction.....................................................................................1
Location and accessibility............................................................................. 1
Geologic setting.............................................................................................. 8
Previous work................................................................................................12
Purpose and methods...................................................................................13
Chapter 2: FAULT RELATED STRATIGRAPHIC RELATIONSHIPS.........15
General introduction to wall rock stratigraphy.................................... 15
Proterozoic gneiss.........................................................................................15
Wall rocks southwest of the K-S fault..................................................... 18
The South fault..............................................................................................19
Age relationships..........................................................................................20
Late movement along the K-S fault....................................................................24
Observation against normal faulting based on timing............................. 26
Chapter 3: GENERAL HELD OBSERVATIONS.............................................. 30
Mechanical nature of the fault.................................................................. 30
Fault geometry from mapped relationships..........................................34
Chapter 4: KINEMATIC INDICATORS.............................................................38
Introduction..................................................................................................38
P a rti: MESOSCOPIC INDICATORS.....................................................38
Slickenside striae............................................................................. 38
Stereonet plots of striae...................................................... 46
Plots of total striae...............................................................46
Tension gashes.................................................................................57
Fabrics in the fault gouge...............................................................57
Part 2: MACROSCOPIC INDICATORS..................................................65
Fault slivers......................................................................................... 65
Secondary and splay faults................................................................. 70
Distinct structural domain adjacent the K-S fault.................... 75
The Kokoweef syncline.................................................................. 78
Deflections within the Paleozoic units..........................................82
The Kokoweef fault and gneissic foliations..................................83
Dike in the New York Mountains.................................................. 83
iii
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Chapter 5: DISCUSSION........................................................................................85
Discussion of the kinematic evidence.......................................................85
Tectonic implications................................................................................... 88
Chapter 6: CONCLUSION.....................................................................................93
iv
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LIST OF FIGURES
Figure 1: Field area location map.......................................................................... 4
Figure 2: Schematic map showing the location of the K-S fault.....................6
Figure 3: Map showing location of the K-S fault with respect
to the magmatic arc and the thrust belt........................................11
Figure 4: Stratigraphic column of rock units in the study area.......................17
Figure 5: Schematic map showing fault age relationships...............................22
Figure 6: Photograph of intrusive contact between
Mid Hills Adamellite and Proterozic gneiss...............................25
Figure 7: Photograph of marble breccia...............................................................27
Figure 8: Photograph of contact between Mid Hills pluton
and marble breccia........................................................................... 28
Figure 9: Photograph of wide brittle shear zone in the gneiss........................31
Figure 10: Photograph of vertical fault and shear fabric in the gneiss..32
Figure 11: Photograph of vertical fault and shear fabric in the gneiss..33
Figure 12: Photograph of vertical fault surface.................................................36
Figure 13: Photograph of vertical fault surface.................................................37
Figure 14: Photograph of sub-horizontal striae................................................. 40
Figure 15: Photograph of sub-horizontal striae.................................................41
Figure 16: Photograph of sub-horizontal striae.................................................42
Figure 17: Photograph of sub-horizontal striae.................................................43
Figure 18: Photograph of sub-horizontal striae.................................................44
Figure 19: Photograph of sub-horizontal striae..........................................................45
Figure 20: Map diagram allowing alciunei. ploia of striae.............................. 48
v
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Figure 21: Map diagram showing steronet plots of striae................................50
Figure 22: Map diagram showing steronet plots of striae................................52
Figure 23: Stereonet plot of total striae................................................................ 54
Figure 24: Plot of dip of slickensided surface versus rake of striae................56
Figure 25: Photograph of vertical tension gash...................................................58
Figure 26: Photograph of vertical tension gashes...............................................59
Figure 27: Photograph and sketch of gouge fabrics........................................... 62
Figure 28: Photograph and sketch of gouge fabrics............................................64
Figure 29: Schematic map diagram of fault slivers with respect
to their probable source areas.........................................................67
Figure 30: Photograph of carbonate fault sliver...................................................69
Figure 31: Sketch map showing fault splay in the New York Mountains..74
Figure 32: Map of distinct structural..................................................................... 77
Figure 33: Simplified map of Kokoweef syncline.............................................. 81
vi
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LIST OF PLATES
Plate 1: 1:6000 scale geologic strip maps of K-S fault in the
Mescal and Ivanpah Ranges..................................... map pocket.
Plate 2: 1:6000 scale geologic strip map of K-S fault in the
New York Mountains.................................................map pocket.
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Abstract
The Kokoweef-Slaughterhouse (K-S) fault in the eastern Mojave
desert, represents a major mid-Cretaceous, intra-arc, left-lateral, strike-slip
fault. This northwest-striking fault, more than 40 km in length, juxtaposes a
northeastern wall of Proterozoic gneiss against a southwestern wall of
predominantly Paleozoic and Mesozoic units. The timing of K-S faulting is
tightly constrained by the age of the Delfonte Volcanics (100.5 ± 2 Ma, Fleck et
al 1994), the youngest unit it cuts, and the lower age limit on Keaney Pass-
Mollusk Mine thrusting across it. This latter age is provided by Teutonia
batholith plutons that intrude the upper plate of the thrust (Miller et al, 1996;
Burchfiel and Davis, 1971). Cross-cutting relationships indicate that the K-S
fault was active either concurrently with, or in between, episodes of east- to
northeast-directed thrust faulting. Sinistral displacement along the K-S fault
is attributed to strain partitioning during left-lateral oblique subduction of
the Farallon plate beneath North America.
Field work along the K-S fault included detailed mapping and the
investigation of fault-related structures, and was used to establish the nature
of faulting. The fault's nearly vertical geometry coupled with predominantly
horizontal slickenside striae indicate a strike-slip-dominated history.
Stratigraphic displacements on related second order faults as well as the
relative positions of fault slivers with respect to their probable source areas
viii
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consistently indicate sinistral displacement.
Brittle fault-related deformation was concentrated within the
Proterozoic gneiss, whereas the dominantly carbonate southwestern wall
rocks display a relative lack of deformation. Foliation in the gneiss is
subparallel to the fault and served as planes of weakness along which slip
was accommodated.
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Chapter 1: INTRODUCTION
General introduction
The Kokoweef-Slaughterhouse fault is a mid-Cretaceous, intra-arc
fault in the eastern Mojave Desert, California. This northwest-trending
fault has been interpreted as both a large normal fault (Hewett, 1956) and a
strike-slip fault (Burchfiel and Davis, 1977); however, very little evidence
for either of these interpretations has been presented. Tight age constraints
on this major structure suggest that it was active concurrently with
thrusting in the foreland fold and thrust belt. In light of this a better
understanding of Kokoweef-Slaughterhouse kinematics would provide
im portant information regarding mid-Cretaceous tectonics and plate
interactions along the western margin of North America.
Location and accessibility
The Kokoweef-Slaughterhouse (K-S) fault is located within the
northeastern portion of the East Mojave National Scenic Area, San
Bemadino County, California. The fault can be traced for almost 40 km
through, from northeast to southwest, the Mescal, Ivanpah and New York
mountain ranges (Fig. 1).
The field area for this study includes an approximately 1/2 to 3/4
kilometer-wide strip along the surface trace of the K-S fault. The
1
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northernm ost trace of the fault is located approximately 1 km southeast of
the Mountain Pass summit on U.S. Interstate 15, where it disappears
beneath the frontal thrust of the Clark Mountains fold and thrust belt (Fig.
2). The southernmost exposure of the fault trace in the Ivanpah
Mountains is located approximately 1 km northwest of the Allured Mine
in the New Trail Canyon area of the range. East of the Ivanpah Mountains
is the southern end of Ivanpah Valley, which lies between the Ivanpah
Range to the west and the New York Mountains to the east. There are no
exposures of the K-S fault within the valley. Across Ivanpah Valley the K-
S fault is offset sinistrally -12 km along the alluvium buried Nipton fault
zone, which has a roughly northeasterly trend through Ivanpah Valley
(Hewett, 1956; Swanson, 1980; Burchfiel and Davis, 1977; Wooden and
Miller, 1993). This offset is strongly supported by stratigraphic relationships
across the valley as well as gravity anomalies within Ivanpah Valley
(Hewett, 1956; Swanson, 1980; Burchfiel and Davis, 1977; Wooden and
Miller, 1993).
The Slaughterhouse (S) segment of the fault is exposed south of
Ivanpah Valley in the New York Mountains. Exposures of the fault are
quite impressive in this range, in part due to extensive excavation along
the fault in search of fault-controlled mineralization. In many cases
m ining roads run along the fault trace providing excellent opportunities to
examine the shear zone. The northwestem m ost exposure of the S segment
o
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Figure 1. Map of Southern California showing the general location of the
study area depicted by the dashed rectangle within the East Mojave
National Scenic Area. (Modified from Miller et. al. 1991)
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Lone Pine
Las Vegas
■ F ig . 2
Baker
EAST MOJAVE
NATIONAL
SCENC AFEA
LosAngeli
Bernadno
Santa Ana
Palm Springs
□ego
Centro
MEXICO
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Figure 2. Schematic map showing the location of the Kokoweef-
Slaughterhouse Fault with respect to geographic features in the
general vicinity. Dashed lines surrounding the K-S fault outline
locations shown on Plates 1 and 2, and figures 19-21.
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within the New York Mountains is approximately 2 km northwest of
Slaughterhouse Spring on the northwestern edge of the mountain front.
To the southwest the fault trace can be followed across the New York
Mountains until it is intruded out by a Mesozoic pluton and disappears
beneath alluvium approximately 1 km north-northwest of Lecyr Well.
In the Mescal and Ivanpah Mountains the K-S fault is easily
accessible via various dirt roads. These roads can be accessed by driving east
arid south from the Bailey Road exit near the summit of Mountain Pass on
Interstate 15. The southeastern segment of the K-S fault in the Ivanpah
Range is easily reached from a dirt mining road that heads west off of
Morning Star Mine road toward the New Trail Mine. The northwestern
segment of the fault in the New York Mountains can be reached via a well-
graded dirt road that branches southeast off of Ivanpah Road towards
Slaughterhouse Spring. From Slaughterhouse Spring the
northwestem most exposure of the K-S fault m ust be reached on foot. 4-
WD mining roads follow the fault toward the southeast from
Slaughterhouse Spring for over a kilometer. The southeastemmost
exposures of the fault are easily reached from a dirt road, that heads
northwest from Ivanpah road towards Trio Mines, approximately 1.5 km
southwest of Barnwell (Fig. 2).
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Geologic setting
The K-S fault lies within an area of the North American Cordillera
that has experienced a long and complex history that includes episodes of
metamorphism, orogenesis, erosion, sedimentation and arc magmatism.
Rock units in the field area range in age from early Proterozoic (-1.7 Ga) to
mid-Cretaceous. The principle rock units of the study area include
Proterozoic crystalline rocks, a Paleozoic cratonal sequence, Mesozoic arc-
related volcanic and plutonic rocks, and Mesozoic sedimentary rocks.
The Proterozoic crystalline basement comprises amphibolite grade
metasedimentary and meta-igneous rocks that include biotite-gamet-
sillimanite gneiss, granitic augen gneiss, amphibolite, hornblende gneiss,
tonalitic gneiss, and granitoid gneiss (Burchfiel and Davis, 1977; Wooden
and Miller, 1990). Gneisses are early Proterozoic and yield U /Pb ages
around 1.7 Ga (Lanphere, 1964; Wooden and Miller, 1990). Precambrian
basement is unconformably overlain by a Paleozoic cratonal sequence
(Burchfiel and Davis, 1977), basal units of which include the early
Cambrian Tapeats sandstone and the overlying Bright Angel shale. Higher
units in the sequence are predom inantly carbonate rocks of the Bonanza
King, Nopah, Sultan, Monte Cristo and Bird Springs formations. There is
no record of Paleozoic deformation in the field area.
The Mesozoic geology of the area is dominated by arc magmatism
and northeast-directed thrust faulting related to the inception of eastward
8
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subduction beneath the western edge of North America (Burchfiel and
Davis, 1977, 1981). The K-S fault occupies an area that lies near the eastern
margin of a Jura-Cretaceous arc. Although Mesozoic rocks in the field area
are dom inantly plutonic and volcanic in origin, Triassic, Jurassic and
Cretaceous sedimentary units are also present (Triassic Moenkopi and
Chinle formation, Jurassic Aztec Sandstone, and Cretaceous elastics in the
Delfonte volcanic sequence). Deformation in the Mesozoic was mostly
contractional in nature and included several episodes of folding and
northeast-directed thrust faulting that have been thoroughly documented
in the New York, Clark, Spring, Mescal and Ivanpah m ountain ranges
(Burchfiel and Davis, 1971, 1977, 1988; Dunne and others, 1978; Fleck,
1970). The K-S fault is located within the eastern edge of the Sevier fold
and thrust belt in an area near the Califomia-Nevada state line where the
strike of the belt changes southwards from northeast to northwest (Fig. 3).
This change in strike is associated with a distinct change in the nature of
deformation within the belt (Burchfiel and Davis, 1975; 1988). South of the
bend several major N- to NW-striking thrust faults cut through
supracrustal strata and involve crystalline basement. In contrast, the NE-
striking thrust faults of the belt to the north (Fig. 3) do not involve the
basement at present levels of exposure and exhibit bedding parallel controls
on their geometry of detachment (Burchfiel and Davis, 1975, 1988).
9
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Figure 3. Map showing the location of the Kokoweef-Slaughterhouse fault
with respect to the eastern limit of the 135-80 Ma magmatic arc and
major thrust faults of the Cordilleran foreland fold and thrust Belt
(modified from Burchfiel and Davis, 1981).
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Eastern limit of
magmatic arc
135-80 Ma
Las ^ gas N
N v v i K-S Fault
Baker
Barstow
Los Angeles
Mexico
100 mi
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Previous work
The earliest published geologic work in the area was done by Hewett
during the 1920's, although his USGS professional paper was not published
until 1956. Hewett (1956) mapped the present day K-S fault as part of a large
northwest-striking normal fault that he nam ed the Clark Mountain fault.
Later m apping in the area determined that what Hewett (1956) had mapped
as a single normal fault was indeed two separate faults with quite different
kinematic histories (Burchfiel and Davis, 1971). The northern segment of
Hewett's Clark Mountain fault was rem apped as the frontal thrust fault in
the Clark Mountain thrust complex that emplaced Cambrian Bonanza King
rocks over older Proterozoic gneiss, Cambrian Tapeats and Bright Angel
Shale (Burchfiel and Davis, 1971). The remaining southern section of
Hewett's Clark Mountain normal fault was remapped as a high angle fault
referred to as the Kokoweef fault in the Ivanpah and Mescal Ranges and
the Slaughterhouse fault in the New York M ountains (Burchfiel and
Davis, 1971,1977). Like Hewett (1956), Burchfiel and Davis believed that
the Kokoweef and Slaughterhouse faults represented segments of the same
fault; however, the high angle nature of the fault along with limited field
observations led Burchfiel and Davis to suggest a left-lateral strike-slip
origin for the fault. Geophysical work including both seismic refraction
and magnetic surveys determined that the K-S fault in the New Trail
Canyon area of the Ivanpah Mountains extends towards the south beneath
12
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the alluvium of Ivanpah Valley rather than curving towards a more
easterly direction as indicated by Hewett (1956; cf. Swanson et al., 1980).
This appears to support the idea that the K-S fault is left laterally offset -12
km across Ivanpah Valley (Swanson et al., 1980). Mapping in the New
York Mountains by Miller and Wooden (1993) further supports a sinistral
strike-slip interpretation for the K-S fault. Although many suggestions
have been made regarding the history of the K-S fault, convincing evidence
regarding the faults kinematics had yet to be presented at the time this
study was initiated.
Purpose and methods
The prim ary purpose of this project was to establish more clearly the
geometry and kinematic history of the K-S fault. This fault represents a
major structural feature within the eastern edge of the contemporaneous
mid-Cretaceous magmatic arc and the foreland fold and thrust belt of
western North America. Past worker's interpretations regarding the nature
of the fault have varied widely and until now no detailed study of the K-S
fault had been undertaken. This project represents the first detailed study
focusing solely on the nature of K-S faulting and its relationship to the
thrust belt and the magmatic arc. A better understanding of this fault will
undoubtedly lead to an improved conception of the eastern Mojave
region's geologic history during the Cretaceous period. It may also help
13
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further constrain widely debated North American/Farallon plate
interactions during the mid-Cretaceous.
Six weeks were spent in the field investigating and mapping exposed
lengths of the K-S fault. Brittle fabrics and structures (e.g. tension gashes,
slickensides, striae, shear fabrics, and internal gouge structures and fabrics)
were investigated within the fault zone. Detailed field mapping (1:6000)
along the exposed lengths of the fault was crucial to establishing its
geometry as well as any changes in the geometry of wall rock strata and
foliation patterns as they near the fault. Time was also spent looking for
fabrics and structures along the fault that might reveal information on
kinematics.
Topographic base maps were prepared from USGS 1:24,000 7.5
minute quad maps: 1) Ivanpah, 2) Mescal Range, and 3) Mineral Hill. Base
maps were enlarged 400% so mapping could be done at a scale of 1:6000.
Maps were scanned and digitized on Canvas for the Macintosh. Slickenside
and striae data were plotted using the Stereonet version 4.5.2 1988-1992
program by Allmendinger (Almendinger, 1988-1992).
14
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CHAPTER 2: FAULT-RELATED STRATIGRAPHIC RELATIONSHIPS
General introduction to wallrock stratigraphy
The NNW-striking K-S fault juxtaposes an eastern footwall of
Proterozoic gneiss (-1.7 Ga; Lanphere, 1964; Wooden and Miller, 1990)
against a western hanging wall of Paleozoic and Mesozoic strata (Fig. 4) and
Mesozoic plutons. The fault consistently dips steeply to the southwest (avg.
-80 degrees). This apparent hangingwall down with respect to footwall
relationship as most simply interpreted would seem to indicate that the
fault is a normal fault; however, several lines of evidence that are
discussed in later sections dispute this simple interpretation. The largest
stratigraphic throw along the fault is present just south of 1-15 at Mountain
Pass. Here, Cretaceous Delfonte Volcanic rocks are juxtaposed against
Proterozoic gneisses unconformably overlain north of 1-15 by Tapeats
Sandstone and Bright Angel Shale. Burchfiel and Davis estimate the
stratigraphic throw here as approximately 2500 meters (Burchfiel and
Davis, 1977).
Proterozoic gneiss
Proterozoic metamorphic rocks in the footwall of the fault includes
biotite-gamet-sillimanite gneiss, granitic augen gneiss, am phibolic,
hornblende gneiss, tonalitic and granitoid gneiss (Wooden and Miller,
15
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Figure 4. Stratigraphic column of rock units in study area north of Ivanpah
Valley (modified from Burchfiel and Davis, 1971).
16
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SCRLE IN METERS
1829
1737
1646
1555
1463
1372
1280
1189
1097
1006
914
823
732
640
549
457
366
274
183
91
0
DELFONTE VOLCANIC
ROCKS (100.5 ±2 Ma)
AZTEC SANDSTONE (Jurassic)
ClilNLE FORMATION (Triassic)
MOENKGPI FORMATION (Triassic)
KAIBAB FORMATION (Permian)
CONTACT NOT EXPOSED
AMOUNT OF SECTION MISSING UNKNOWN
BIRD SPRINGS FORMATION (Penn-Perm)
MONTE CRISTO LIMESTONE (Miss)
SULTAN LIMESTONE (Devonian)
NOPAH FORMATION (Cambrian)
BONANZA KING
FORMATION (Cambrian)
BRIGHT ANGEL SHALE (Cambrian)
TAPEATS SANDSTONE (Cambrain)
GNEISS (Proterozoic - 1.7 Ga)
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1990; Burchfiel and Davis, 1977). In the field area gneissic foliations have
an average orientation of about N30W 60 SW. Little time was spent
mapping in the gneiss, except in cases where foliations were mapped out in
hope of finding near-fault deflections or geometeries that might shed light
on the kinematics of faulting. A number of foliation measurements in the
gneiss were recorded in order to track foliation patterns and their
relationship w ith the fault. Because the K-S fault, for the most part, is
subparallel to foliation in the gneiss little evidence of fault-related
deflections was found.
Wall rocks southwest of the fault
Paleozoic and Mesozoic units in the study area have experienced
contractional deformation related to episodes of thrust faulting both prior
to and following K-S high angle faulting. Multiple episodes of deformation
have been documented by Burchfiel and Davis (1971, 1988), including a
thrust in the Delfonte Volcanics and folds that are truncated by the K-S
fault.
The Paleozoic cratonal sequence is dominantly carbonate. In general,
the carbonate rocks display significantly less brittle deformation along the
fault than does the Proterozoic gneiss. In only a few places along the fault
are carbonate fault breccias present with thicknesses of more than 1 meter.
The strength of the carbonate rocks, especially dolomite, appears to have
18
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been much greater than that of the gneiss with its inherent anisotropies.
No evidence for ductile deformation of carbonate rocks was found adjacent
to the fault in the Ivanpah Mountains. However, clear evidence of ductile
deformation within marbles of the Bird Springs Formation is present
adjacent to the Mid Hills Adamellite pluton along the fault, northwest of
Slaughterhouse Spring in the New York Mountains. In this location a
fault subparallel foliation in the recrystallized carbonates adjacent to the
fault indicates ductile behavior. The lack of this foliation elsewhere along
the fault suggests that heat from the intruding pluton locally raised
temperatures enough to allow the carbonates to deform in a more ductile
fashion.
The South fault
In the Mescal Range the Kokoweef fault (Strip A, Plate 1) may either
merge into or be cut by a fault called the South fault by Olson (1954).
Establishing the existence and determining the type and am ount of offset
along the South fault is difficult because the fault juxtaposes Proterozoic
gneiss against nearly identical Proterozoic gneiss. Although my field work
failed to conclusively prove the existence of the South fault, m apping done
by Olson (1954), which included detailed work in the Proterozoic gneisses,
indicated that this fault was evident from the differences in the gneisses
across the fault as well as from truncation of shonkinite and granite dikes
19
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along it. According to Olson (1954) the South fault displays a left-lateral
offset of 1920 m based on a displaced belt of rare earth and thorium
deposits. Olson interpreted that the South fault truncated the Kokoweef
fault, although the presence of fault slivers of Kaibab limestone along the
northeastern section of Olson's South fault (west of its supposed junction
with the K-S fault), similar to Kaibab slivers found along the Kokoweef
fault southwest of the junction, suggest that the Kokoweef fault is
continuous around the bend, ie. it is not cut off by the South fault.
Accordingly, I interpret the northwestern segment of the "South fault"
simply as the continuation of the K-S. W hether the South fault exists or
not, the critical age relationships in this area are not re-arranged.
Age relationships
The age of the most substantial movement along the K-S fault is
very well constrained by various crosscutting relationships (Fig. 5). For
example, the Kokoweef segment of the fault in the Mescal Range cuts the
Delfonte Volcanics and juxtaposes them against Proterozoic gneiss.
Detailed geochronologic work done on these volcanics by Fleck et al. (1994),
involving K-Ar, Rb-Sr and U-Pb techniques, firmly establishes a 100.5 ± 2
Ma age of crystallization for the Delfonte volcanics. This relationship
indicates that at least the latest major motion along the K-S fault postdates
the mid-Cretaceous eruption of the Delfonte volcanics and has a maximum
20
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Figure 5. Schematic diagram showing age relationships between the
Kokoweef-Slaughterhouse fault, Kokoweef-South fault, Keaney Pass-
Mollusk Mine thrust, Delfonte Volcanics and intrusive rocks in the
Mescal, Ivanpah and New York Mountains.
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KeaneyPass/Mollusk Mine thrust
Delfonte Volcanics
-1 0 0 5 + 2 Ma
\ 100.5 M a > K -S > 95
Teutonia batholith
U-Pb~95i2Ma
Mid Hills Adameflite
and Live Oak Granite
U-Pb -93 Ma ~~
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age of 100.5 ± 2 Ma. The three highest units of the Delfonte volcanic
sequence are duplicated by thrusting along the Groaner Spring (GS) thrust
(Burchfiel and Davis, 1971). This thrust has a small displacement (~1 km)
and was steeply folded along a west trending synclinal hinge before being
truncated by the Kokoweef fault. To the northwest the Kokoweef fault is
overridden by the Keaney Pass-Mollusk Mine (KP-MM) thrust plate
(Burchfiel and Davis, 1971). The KP-MM thrust cuts the Delfonte Volcanic
sequence, the Groaner Spring thrust and the synform in the volcanics as
well as overlapping the Kokoweef fault. This relationship indicates that
major displacement aiong the Kokoweef fault took place prior to their
being overridden by the Keaney Pass-Mollusk Mine thrust fault.
Pluton relationships establish an upper age for displacement along
the Keaney Pass-Mollusk Mine thrust fault. Plutons of the Teutonia
batholith are inferred by Burchfiel and Davis (1971) to intrude the upper
plate of the Keaney-Mollusk Mine thrust. The batholith exhibits continuity
across southward projections of the frontal thrust and its upper plate of
Paleozoic and Neoproterozoic rock units (Burchfiel and Davis, 1971, 1988).
U-Pb geochronolgy on the Teutonia intrusive suite yields ages of -95 ± 2
Ma (Miller et al., 1996). In the New York M ountains the Slaughterhouse
fault is cut by the Mid Hills Adamellite of Beckerman and others (1982)
which clearly intrudes both walls of the fault (Fig. 6). This pluton yields a
U-Pb age of about 93 Ma (Miller and Wooden, 1993). Further to the
23
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southeast the Slaughterhouse fault also appears to be cut by the Live Oak
Canyon granodiorite of Beckerman and others (1982). [A K-Ar age of 79.9 ±
2.4 Ma (biotite) from this pluton was obtained by Beckerman and others
(1982), although this age relationship does little to constrain the timing of
K-S faulting.] These various crosscutting age relationships bracket the
major activity along the K-S fault between 100.5 ± 2 Ma and -95 ± 2 Ma.
This age range defines the fault as being active within the mid-Cretaceous
magmatic arc and occurring between episodes of thrust faulting (e.g. post-
Groaner Springs thrust, pre-Keaney Pass-Mollusk Mine thrust). The very
close temporal relationships between K-S faulting, foreland fold and thrust
belt thrusting and mid-Cretaceous arc magmatism is a vital part of this
thesis that is addressed in following sections.
Late movement along the K-S fault
The KP-MM thrust fault exhibits minor offset by the Kokoweef fault
that could either have resulted from -0.5 km of sinistral horizontal
displacement or -0.35 km of southwest wall dow n vertical displacement.
Because this offset represents only a small fraction of either the dip-slip or
strike-slip displacement displayed by the Kokoweef fault, it can be explained
by modest reactivation. Along the Slaughterhouse fault, in an area - 1 km
northwest of Slaughterhouse Spring, a sliver of marble nearly 1 km long
and in some places -30 m wide, very likely part of the late Plaeozoic Bird
24
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Figure 6. Photograph of intrusive contact between the Mid Hills Adamellite
pluton (bottom half of photo) and Proterozoic gneiss northeast of the
K-S fault ~ 2 km northwest of Slaughterhouse Spring in the Mew
York Mountains. Contact is visible across the center of the photo
(roughly 5 inches above the head of the rock hammer).
25
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Springs Formation, is present between the K-S fault and the Mid Hills
Adamellite to the west. Field relationships clearly indicate that the contact
between the marble and the pluton is intrusive, although now locally
sheared. The marble displays a fault subparallel foliation adjacent to the
fault, although in some areas closer to the pluton contact the marble is
brecciated (Figs. 7 & 8). At both ends of the marble sliver the pluton is in
intrusive contact with Proterozoic gneiss and amphibolite of the fault's
northeastern wall. Along the Slaughterhouse fault adjacent the marble
sliver, plutonic rocks of the Mid Hills Adamellite display local evidence of
brittle deformation. The presence of these brittle shear zones in the
plutonic rocks indicates an episode of late stage movement or reactivation
along the Slaughterhouse fault that followed the intrusion and cooling of
the Mid Hills Adamellite; however, it does not appear that this later stage
of activity generated much offset, because there is little offset of the pluton
across the fault.
Observations against normal faulting based upon timing relationships
Along the northwestern section of the Kokoweef fault in the Mescal
Range the fault juxtaposes the southwestern wall mid-Cretaceous Delfonte
volcanics against Proterozoic gneiss (Plate 1). This juxtaposition, which is
the largest along the length of the fault, represents an approximate
stratigraphic throw of 2500 meters (Burchfiel and Davis, 1971). If this
26
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Figure 7. Photograph of Bird Springs Marble breccia close to pluton contact
-1.5 km northwest of Slaughterhouse Spring in the New York
M ountains.
27
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Figure 8. Photograph of Mid Hills Adamellite pluton (foreground) in
contact with Bird Springs marble breccia. Photo taken -1.5 km
northwest of Slaughterhouse Spring and - 15 m southwest of the K-
S fault.
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stratigraphic throw were due to normal faulting during the fault's less than
5 million year lifetime, 2500 meters of relief (northeast side up) would have
been generated, ignoring the effects of denudation. However, there is no
evidence of this in the form of sediment shed or deposited to the southwest
across the fault as one might expect. An even more puzzling scenario
develops when the presence of the Keaney Pass-Mollusk Mine thrust fault
is considered. As was previously mentioned, the thrust fault overrides the
northern end of the Kokoweef/South fault, thus providing a key piece to
the timing puzzle. North of the Kokoweef/South fault trace, the thrust
plate sits on upperm ost Precambrian basement rocks and remnants of the
basal Tapeats Sandstone, whereas south of the trace the thrust cuts mid-
Cretaceous Delfonte Volcanics. If displacement along the K-S fault was dip-
slip, prior to the KP-MM thrust fault overriding the Kokoweef/ South
fault, 2500 meters of Mesozoic and Paleozoic material would have had to be
removed. This would require the removal or erosion of 2500 meters of
relief in less than 4-5 million years (Pers. com., G. A. Davis, 1998). Davis
considers it m ore likely that the thrust plate moved across an erosional
surface with Proterozoic rocks north of the K-S fault trace and Cretaceous
rocks south of it.
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Chapter 3: GENERAL HELD OBSERVATIONS
Mechanical nature of the fault
The K-S fault generally displays characteristics consistent with brittle
faulting at relatively shallow crustal levels. In some areas of good exposure
a gouge zone up to 2-3 m in thickness is present. Also consistent with
brittle faulting are the many out-of-place slivers of southwest wall rock
units that crop out along the trace of the fault (Plate 1). Many of these
slivers have been displaced significantly from their probable sources. These
displacements shed light upon K-S fault kinematics and are discussed in
following sections. They vary from 1 to 10 meters in width and 5 to 150
meters in length. The slivers consist dominantly of carbonate material
derived from the Kaibab and Moenkopi Formations, although, slivers of
Tapeats sandstone and Bright Angel shale have also been found (Plate 1
and Fig 30).
As further evidence for the predominantly brittle nature of
Kokoweef faulting, wide brittle shear zones (< 50 meters)affect the
Proterozoic gneiss adjacent to the fault (Fig. 9). Within these shear zones
the gneiss displays a fabric that is subparallel with the nearly vertical fault
(Figs. 10 & 11).
An exploratory tunnel into the northeast side of Kokoweef Peak in
the Ivanpah M ountains crosses the fault, thus providing an excellent
30
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Figure 9. Photograph taken up through wide zone of brittlely sheared
Proterozoic gneiss below the K-S fault ~ 2 km southeast of Kokoweef
Peak in the Ivanpah Mountains. K-S fault is located at the base of
the gray carbonate rocks in the background.
31
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Figure 10. Photograph of K-S fault in the New York Mountains.
Photograph displays nearly vertical fault contact between
Proterozoic gneiss (left) and carbonate of the Bird Springs Formation
(right). Proterozoic gneiss displays well developed, vertical, brittle,
shear fabric. View is to the southeast and parallel to the fault.
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Figure 11. Photograph of K-S fault in the New York Mountains.
Photograph displays vertical fault contact between Proterozoic
gneiss (left) and carbonate of the Bird Springs Formation (right).
Proterozoic gneiss displays well developed shear fabric. View is to
the southeast parallel the fault. Standard rock ham m er for scale.
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opportunity to view a cross- section of the fault zone. The approximately 35
meter-wide fault zone is located roughly 100 meters in from the portal of
the tunnel. W ithin this extensively sheared fault zone are many large
slivers of carbonate and smaller slivers of gneiss separated by steeply
dipping (70-90°) zones of localized shear. The concentration of shear bands
roughly increases towards the center of the zone, which is defined by a ~1
meter wide gouge zone bordered on both sides by fault breccia.
Near the Mid Hills pluton in the New York Mountains, in contrast
to the brittle faulting described above more ductile fault deformation is
indicated by a sharp fault contact between gneiss and limestone as well as a
fault subparallel foliation in the limestone. It is possible that deeper levels
of the fault are exposed here, and that much of the evidence for brittle
faulting in the New York Mountains may be a consequence of overprinting
caused by late stage movement or fault reactivation.
Fault geometry from mapped relationships
A substantial portion of the field work was focused on detailed
m apping along the fault in order to determine its geometry. The entire
exposed length of the fault was mapped. Strike and dip measurements of
the exposed fault surface as well as slip surfaces in exposed portions of the
gouge zone were taken wherever possible.
34
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The 1:6000 scale m aps display a linear fault trace that shows little to
no topographic deflection with few exceptions. In the Ivanpah mountains
the Kokoweef fault has a consistent strike of around N28W. The
Slaughterhouse fault in the New York mountains has a very similar strike
of around N30W. The very consistent linear trace of the fault is consistent
with a very high angle fault and compatible with outcrop measurements of
the fault surface and shear zone; strike was consistently N20-30W, with
dips consistently very steep to the southwest and averaging -80°. The fault
surface is exposed in a few locations as a nearly vertical wall of marble or
limestone, in some cases standing over 6 meters high (Figs. 12 & 13).
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35
Figure 12. Photograph of vertical carbonate fault surface in the New York
Mountains. Rock hammer hanging on exposed fault surface for
scale (hammer located just to the right of center).
36
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Figure 13. Photograph of vertical carbonate fault surface (~6 m high) in the
New York Mountains. Left half of picture displays brittlely sheared
gneiss exposed in a road cut. Diagonal black line across photo is a
cable left over from mining operation.
37
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Chapter 4: KINEMATIC INDICATORS
Introduction
Because only two units can be matched across the fault north of Ivanpah
Valley (Proterozoic gneiss and CambrianTapeats Sandstone), and because
these offset units shed only limited light on the kinematics of faulting, one
is forced to rely on other methods in order to determine the history of K-S
faulting.
Part 1: MESOSCOPIC INDICATORS
Slickensides and striae
Close attention was paid to kinematic indicators that might be useful
in determining the history of slip along the K-S fault. Among the various
types of kinematic indicators found in the field, slickensides and striae
(slickenlines) were the most abundant and have proven to be useful. More
than one hundred striae measurements were taken and recorded in the
field. Most were taken from within the damage zone along the main fault
as well as on the fault surface itself. Important striae measurements were
also taken from two second order related faults in the Ivanpah and New
York Mountains. Both strike and dip of the slickensided fault plane and
trend and plunge of the striae were measured. In many cases the rake of
38
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striae were measured as a proxy to direct measurements of trend and
plunge.
Along much of the Kokoweef fault the most impressive exposures of
the fault surface occur in the carbonate rocks due to their relatively
resistant nature in comparison to the extremely sheared gneiss. These
exposures, which often stand out like carbonate walls along the
mountainsides, very often lacked striae. This lack of striae is most likely a
function of weathering of the exposed carbonate fault surface. When
present on these carbonate fault surfaces the striae often appeared as
parallel grooves on rough weathered planar surfaces (Fig. 14).
Many of the slickenside and striae measurements were taken from
within the zones of sheared Proterozoic gneiss adjacent to the fault. The
majority of striated fault surfaces are parallel or subparallel to the main
fault. These dominantly steep dipping fault surfaces host striae that are
mainly within 20 to 30 degrees of horizontal (Figs. 15,16,17 & 18).
Spectacular striae and slickensides are found at a few locations. One
such place is where the exploratory tunnel, discussed earlier, crosses the
fault on the east side of Kokoweef Peak. At this location, impressive striae
were identified and measured on slip surfaces within the gouge (Fig. 19).
Once again the majority of surfaces were parallel to the main fault and the
striae were dominantly within 20 to 30 degrees of horizontal.
39
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Figure 14. Photograph of nearly vertical K-S fault surface exposed on
carbonate unit in the Ivanpah Mountains. Horizontal grooves
weathered fault surface represent slickenside striae.
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Figure 15. Photograph of striae on K-S fault surface in the New York
Mountains. Pencil held horizontal. Rake of striae ~ 25°.
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Figure 16. Photograph of nearly horizontal striae on vertical slickensided
fault surface exposed in Delfonte Volcanic rocks adjacent the
Kokoweef/South fault near Groaner Spring. Slickensided surface is
parallel to, and within a few meters of the fault.
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Figure 17. Photograph of nearly vertical slickensided fault surface
containing horizontal striae exposed in Proterozoic gneiss adjacent
the K-S fault in the Ivanpah Mountains. Pencil for scale represents
horizontal.
43
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Figure 18. Photograph of nearly vertical slickensided fault surface exposed
in the Cambrian Tapeats Sandstone adjacent to the K-S fault in the
Ivanpah Mountains. Striae rake ~25° to the southwest.
44
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Figure 19. Photograph of vertical slickensided fault surface exposed within
shear zone in Crystal Cave Tunnel. Striae on surface are horizontal.
45
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Stereonet plots of striae
Slickenside and striae measurements were plotted on equal area
stereonets using the Stereonet version 4.5.2 (copyright 1988-1992) program
by R. Almendinger in order to illustrate the geometry of each slip surface.
A few different types of stereonet plots were produced in order to analyze
and display the measurements in various ways.
One of the plots displays both slickenside and striae measurements
(Figs. 20, 21 & 22). Measurements from the same area were plotted together
on the same stereonet. This consequently produced many plots that
allowed the characteristics of the slickenside and striae measurements from
different regions along the fault to be examined and interpreted separately.
Plots of total striae
All striae measured in the field are plotted on Fig. 23. From this plot
it is easy to see that the majority of striae plunge either to the southeast or
northwest and lie within 20 to 30 degrees of horizontal, indicative of strike-
slip motion. Striae and slickensides are also displayed on a diagram in
which the dip of the slickenside surface is plotted versus the rake of the
striae on that surface (Fig. 24). This plot enables one to correlate the
orientation of the striae to the geometry of the fault surface containing it.
For different types of fault motion one would expect data to cluster in
46
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Figure 20. Map diagram showing equal area stereographic projections of
striae (dots) and slickensides (great circles) from data recorded along
the northern segment of the Kokoweef segment of the fault in the
Mescal and Ivanpah Ranges (location shown on figure 2). Delfonte
Volcanics (Kdv), Jurassic Aztec Qa), Triassic Chinle (Trc), Triassic
Moenkopi (Trm), Permian Kaibab (Pk), Pennsylvanian-Permian Bird
Springs (PPbs) and Proterozoic gneiss (P£g).
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1 Km.
a,
48
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Figure 21. Map diagram showing equal area stereographic projections of
striae (dots) and slickensides (great circles) from data recorded along
the K-S fault near Kokoweef peak and in the New Trail Canyon Area
(location shown on figure 2). Pennsylvanian-Permian Bird Springs
(PPbs), Cambrian Bright Angel Shale (£ba), Cambrian Tapeats
Sandstone (£t), and Proterozoic gneiss (P£g).
49
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PPbs
peg
Kokoweef
Peak *
K ok ow eef-S lau gh terh ou se
Fault N
-6ba
-Gt
peg
Fault
Gbntact
1 Km.
50
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Figure 22. Map diagram showing equal area stereographic projections of
striae (dots) and slickensides (great circles) from data recorded along
the K-S fault in the New York Mountains (location shown on figure
2). Quaternary Alluvium (Qal), Mid Hills Adamellite (Kmh),
Mesozoic metavolcanic rocks (Mmvs), Mesozoic calcsilicate rocks
(Mcs), Pennsylvanian-Permian Bird Springs (PPbs), and Proterozoic
gneiss (P£g).
51
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peg
\ v Q a l
PPbs
Kmh
C ^ / ''Kmh
P P b s\ 7
Qal
P6g
PPbs
52
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Figure 23. Equal area stereographic projection of striae recorded along the
K-S fault and its major splays.
53
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Equal Area
n=112
54
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Figure 24. Plot of dip of slickensided surface versus the rake of the striae
upon that surface for all such data collected along the K-S fault and
its major splays. Density of data in the upper left comer of the plot is
most consistent with strike-slip faulting.
55
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particular locations on the plot. The assum ption is that vertical faults with
horizontal striae most likely represent strike-slip faults and shallower
dipping faults with striae that rake at a high angle represent dip slip faults.
Data collected from the K-S fault zone cluster in the upper left quadrant of
the plot. This is most consistent with strike-slip to slightly oblique motion
within the zone.
Tension gashes
At a few locations calcite-filled tension gashes were found on the
exposed fault surface and in the southwestern wall rocks adjacent to the
fault. In every instance they had near vertical to vertical orientations
suggestive of strike-slip motion (Figs. 25, 26). At one location, less than half
a meter from the exposed K-S fault surface in the New York Mountains,
tension gashes have an average orientation of N37°E 90°. The exposed
fault surface nearest this location has an attitude of N70°W 85° SW. Striae
measured on this fault surface rake from 4° to 16° and plunge towards the
southeast.
Fabrics in the fault gouge
Gouge zones of varying width are present at some locations along
the fault. At some locations fabrics in the gouge were found and interpreted
for sense of shear. The gouge in some locations has a composite planar
57
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Figure 25. Photograph of vertical caldte filled tension gash on exposed K-S
fault surface in the New York mountains. Pencil is being held
vertically for scale.
58
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Figure 26. Photograph of nearly vertical calcite filled tension gashes
exposed in Bird Springs Formation adjacent the K-S fault in the New
York Mountains. Look direction is straight down. Tension gashes
are oriented an average of N 37° E 90°.
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fabric defined by two major components: 1) a foliation characterized by the
preferred alignment of clay minerals, and 2) bands of high intensity
localized shear. Foliations in gouge elsewhere have been interpreted as
forming from the accumulation of finite strain. Such foliation is believed
to occur in two possible ways: 1) simply by rotation of phyllosilicate
minerals (clay), or 2) through their controlled oriented growth (Williams,
1977; Oertel, 1983; Rutter, 1986). The K-S fault gouge sometimes displays a
compositional lamination defined by changes in color. In most cases these
laminations are parallel with the foliation in the gouge fabric.
One of the best locations for observing gouge fabrics along the fault is
located in the New York Mountains less than half a kilometer southeast of
Slaughterhouse Spring. At this location the gouge zone is less than a meter
or so wide, and displays fabrics similar to the S-C fabrics of mylonitic rocks
(Lister and Snoke, 1984; Chester and Logan, 1987). All shear-sense
observations made in planes parallel to slip directions appear consistently
to indicate a dextral sense of shear along the Slaughterhouse segment of the
fault (Figs. 27 & 28).
At another location along the K-S fault in an excavation less than a
kilometer south of Kokoweef Peak in the Ivanpah Mountains (Strip B,
Plate 1), fabrics in the meter-thick fault gouge also similar to that described
above yield the opposite shear sense (sinistral) of that found in the gouge of
the New York mountains. No pictures are available due to poor lighting.
60
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Figure 27. Photograph and sketch of composite planar fabric displayed by
fault gouge along the K-S fault in the New York Mountains. View
to southwest.
61
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Figure 28. Photograph and sketch of composite planar fabric displayed by
fault gouge along the K-S fault in the New York Mountains. View
to southwest
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Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
PART 2: MACROSCOPIC INDICATORS
Fault slivers
Fault-bounded slivers of rock units exposed southwest of the fault
give indication at several locations along the main K-S fault zone of the
likely shear sense during the primary episode of fault displacement. In
many cases these lensoidal slivers of material are located in areas within
the fault zone a few kilometers or more from the nearest outcrop or
exposure of the matching formation from which they could have been
derived.
For example, along the northwestern end of the Kokoweef segment
of the fault in the Mescal Range, several large (5 to 150 m) slivers derived
from the Kaibab Formation outcrop within the fault zone on both sides of
the faults possible junction with the South fault (Fig. 29, PI. 1). They are
stratigraphically very out of place at locations where the fault juxtaposes
Jurassic Aztec Sandstone and Delfonte Volcanics against the Proterozoic
gneiss. The area from which the slivers of Kaibab were very likely derived
is buried beneath alluvium southeast of the Mescal Range, but its location
is reasonably well constrained. Slivers of Kaibab lie from 1 to nearly 4
kilometers northwest of this source area.
At another location, near where the Kokoweef segment of the fault
and South fault join, slivers derived from the Kaibab, Moenkopi and
65
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Figure 29. Schematic map diagram illustrating the location and probable
source areas for fault slivers within the K-S fault zone in the Mescal
and Ivanpah Mountains. Delfonte volcanic rocks (Kdv), Jurassic
Aztec (Ja), Triassic Chinle (Trc), Triassic Moenkopi (Trm), Permian
Kaibab (Pk), Pennsylvanian-Permian Bird Springs (PPbs),
Mississippian Monte Cristo (Mm), Devonian Sultan (Ds), Devonian-
Cambrian Bonanaza King (£bk), Cambrian Bright Angel (£ba),
CambrianTapeats (£t), Proterozoic gneiss (P£g).
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P k (Min. left lateral strike-slip displacem ent ~3.7km.)
FJk £Min. left lateral strike-slip displacement ~2.7km.)
Pk (Min. left lateral strike-slip displacem ent -2km .)
j a ^ rm (Min. left lateral strike-slip displacem ent -1.5km .)
k (Min. left lateral strike-slip displacem ent -lk m .)
Probable Source area for Kaibab and
Moenkopi fault bound slivers
Fault ■
Contact
Trm 0
(Min. left lateral strike- ‘ ^b a
slip displacem ent ~.3km.)
-€bk
( - 3.5 km left lateral _
(Min. strike-slip
displacem ent -.5km .)
_ q (Min. strike-slip
displacem ent -1.5km.)
strike-slip displacem ent) _ 0 ^(N
67
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Chinle formations are adjacent to each other in sequence. At this location
the fault juxtaposes Aztec against Proterozoic gneiss. Once again these fault
bound slivers are significantly out of place. The nearest probable location
from which they were derived lies to the southeast a few kilometers along
the strike of the fault. The presence of such an abundance of complexly
related slivers in this area may be related to either the two faults
intersecting or to the prominent fault bend.
In a few places striated fault surfaces w ere found on these slivers. In
all cases the striae were within 25 degrees of horizontal on nearly vertical
fault surfaces. Near vertical fractures in some of the carbonate slivers may
represent tension fractures further supporting strike-slip movement along
the fault.
In the New Trail Canyon area of the Ivanpah Mountains a sliver of
carbonate material confirms the existence and location of the Kokoweef
fault in a place where the fault is cryptic because it juxtaposes Proterozoic
gneiss against identical Proterozoic gneiss (Fig. 30 & Plate 1). In the same
area a small fault sliver from the basal conglomerate of the Cambrian
Tapeats Formation crops out in the fault zone about a kilometer northwest
of the southeastem m ost exposure of the K-S fault in the Ivanpah
M ountains (Fig. 29). The location of this small sliver is best interpreted as
resulting from sinistral motion along the fault (Fig. 29). Collectively, it is
my interpretation
68
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Figure 30. View to northwest of carbonate sliver along K-S fault in the
New Trail Canyon area of the Ivanpah Mountains. Sliver confirms
the existence and location of the K-S fault in an area where
Proterozoic gneiss lies on both sides of the fault. The fault extends
from the carbonate sliver to the skyline, just right (northeast) of the
dark outcrops of Tapeats Sandstone.
69
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that these slivers represent material that was detached from source areas on
the southwestern wall of the fault and left behind in the fault zone as the
walls moved left-laterally past one another.
Kinematics based on secondary and splay faults
Faults interpreted as being related to the main fault in the New Trail
Canyon and Slaughterhouse Spring areas provide convincing evidence
regarding the kinematics of the K-S fault. In both cases these subsidiary
faults provide stratigraphic information that enables their sense of
displacement to be determined. One of these subsidiary faults located in
the New Trail canyon area of the Ivanpah Mountains branches off of the K-
S fault towards the northwest subparallel to the main fault. It dips between
40 and 75 degrees to the southwest and has a fairly linear surface trace. This
fault juxtaposes a stratigraphic sequence comprising Proterozoic gneiss,
Cambrian Tapeats, Cambrian Bright Angel, Cambrian-Ordovician Bonanza
King Formation and Devonian Sultan Limestone against an extended
sequence of Devonian Sultan southwest of the fault. Restoration of
stratigraphic offsets along this secondary fault indicate an apparent left-
lateral displacement of greater than 3.5 km (Fig. 29). More than 5 km, of
dip-slip displacement would be required in order to produce the observed
offset of the steeply dipping (~70°) strata.
70
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Left-lateral strike-slip displacement along this secondary fault is
further supported by kinematic indicators and slivers of material along the
fault. Cambrian Tapeats Sandstone and lesser amounts of Cambrian Bright
Angel shale are present as fault-bounded slices. These slices lie
approximately 1 kilometer northwest of the point where the fault branches
off the K-S fault (Strip B, Plate 1) and roughly .3 kilometers southwest of
the most probable sources from which they were derived. Striae associated
with this subsidiary fault are predominantly sub-horizontal. Some of the
fault surfaces display congruous steps that are consistent with left-lateral
motion along the fault. Lending further support to this, Cambrian Tapeats
strata at one location very close to the fault are deflected in a manner
consistent with ieft-slip along it (Plate 1).
Near vertical fractures in the Paleozoic carbonates, within a meter
and a half of this fault, may possibly represent tensional features associated
with strike-slip movement along the fault. These fractures increase in
abundance near the fault and truncate into the fault gouge in the center of
the fault zone.
Another less likely interpretation is that this secondary fault
represents an older reverse fault that was then cut by the K-S fault. The
Kokoweef syndine (discussed below) could then be interpreted as a footwall
syncline assoriated with reverse movement along this fault. However, the
stratigraphic offset and the subhorizontal striae along this fault as well as
71
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the current orientation of the Kokoweef syncline with its locally near
vertical hinge are not at all consistent with this interpretation.
To the southeast in the New York M ountains Miller and Wooden
(1993) have m apped two apparent fault splays (Fig. 31). Reconnaissance
mapping by the writer of a portion of the exposed northeastern splay was
done in order to determine its geometry. This splay which branches off of
the main fault towards the northeast is exposed in several excavation pits.
Where exposed the fault zone displays nearly vertical brittle shear bands
and at a few locations yields striae that are within 15 to 20 degrees of
horizontal. The Bird Springs and Monte Cristo Formations, along with
Mesozoic calcsilicates, are offset by these two splays. Miller and Wooden
(1993) interpret these rock units as left-laterally offset by these splays and
suggest a 5-15 km separation along the northeastern splay by matching rock
units and metamorphic grades.
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Figure 31. Sketch map showing possible fault splay from the K-S fault and
metamorphosed Paleozoic and Mesozoic rock units in the New York
Mountains. Taken from Miller and Wooden (1993).
73
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Qal 'M rac
Kmh
PPbs'
2
M cs-V '.-
' •- ••
IM W M *
Mrnrfv
PPbs\
115 15 W
Qal Alluvium (Quaternary)
Live Oak Canyon
Granodiorite (Cretaceous)
Mid Hills Adamellite
(Cretaceous)
Volcanic and Sedimentary
rocks (Mesozoic)
Calc-silicate rocks
(Mesozoic)
Bird Springs Formation
(Penn-Permian)
Monte Cristo Limestone
(Mississippian)
Sultan Formation
(Devonian)
N opah Formation
(Cambrian)
Proterozoic Gneiss
Fault
Contact
1 km
1 mile
35 15 N
74
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Distinct structural domain adjacent the K-S fault
A distinct structural domain is evident in the Mescal Range in the
vicinity of the K-S fault where it takes a more westerly trend (Fig. 32). This
structural domain, which lies in both the footwall and hanging wall of the
Keaney Pass-Mollusk Mine thrust (KP-MM), is characterized by north-
vergent flexural slip folds and north trending striae on the KP-MM fault (G.
A. Davis, pers. communication, 1998). Outside of this small domain, folds
consistently display north to northwest axial trends and structures are
vergent towards the east to northeast. Also within this structural domain,
the axial trend of a major overturned synform involving the Delfonte
Volcanics changes from west to east as it approaches the K-S fault from a
southeast trend through a more westerly trend to a east-northeast trend
(Fig. 32).
This small localized domain, which displays structures that have a
sense of vergence seen nowhere outside of this small region, is best
explained as related to movement on the K-S fault. As mentioned earlier,
cross-cutting relationships indicate that K-S strike-slip faulting and east-
west contraction occurred within the same general time frame (-100-95
Ma). With this being the case, interaction between these two deformational
components would be expected in areas where they come into close
proximity. The observed structural domain, defined by north-vergent
75
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Figure 32. Map showing distinct structural domain adjacent the
K-S fault in the Mescal Range. Folds and thrusts display east-
northeast vergence in the surrounding region, but within the
mapped domain overturned folds (outlined by dashed boxes)
indicate vergence to the north. A major synform (Delfonte synform)
shows a deflection from a northwesterly strike to an easterly strike as
it approaches the fault. Modified from Fleck et al (1994), based on
m apping by Burchfiel and Davis (1971; unpublished).
76
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IMile
Mountain
—3518^
M iiiiir
kriilliji
Surficial tfcposits || | | Bonanza King Formaticn(Cambrian)
Sedimentary deposits Gneiss (Lower FVoterozoic)
Unit 4
Unit 3
Unit 2
Unit 1
m
and breccia t s s sa
Delfcnte
volcaric
rocks
(Cretacecus)
Intrusive rocks (Cretacecus)
Aztec Shndstone (Jurassic)
Chinle formation (Triassic)
Moenkopi formation (Triassic)
Kaibab Formaticn (Fterrrian)
Fault— dashed w here approximately located
Thrust fault
* * * _ __
C ontact— dashed where approximately located
Strike and dip o f beds
Overturned syncline
y Inclined
" ) * * Overturned
Strike and dip o f foliation
- *■ Inclined
Overturned
Syncline
77
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^99999999999999^1
overturned synclines, likely formed as a result of this interaction. Close to
the K-S fault, where east to northeast vergent contractional structures
encountered the northeast wall of the K-S fault, they likely experienced
sinistral drag which led to their counterclockwise rotation. This
explanation is also consistent with the observed deflection of the Delfonte
syncline to a east-northeast axial trend as it approaches the fault.
The Kokoweef syncline
In the Ivanpah Mountains basement gneiss and all overlying
Paleozoic and Mesozoic stratigraphic units southwest of the K-S fault are
involved in a locally overturned syncline with an axial trend that is
adjacent to and subparallel with the fault southeast of Kokoweef Peak (Fig.
33). Near Kokoweef Peak the axis of the syncline takes a more
northwesterly trend and diverges from the fault. The Kokoweef syncline is
typically overturned on its western limb and has a northwesterly plunge
that varies from vertical to subhorizontal along the trace of the axial plane.
The axial trend of the syncline is consistent with regional structures in the
area; however, the variable plunge makes the structure somewhat
enigmatic and difficult to interpret.
The fault-parallel axial trend of the fold, and the fold's close
proximity to the K-S fault together with its unusual geometry in
comparison with regional structures, may suggest a fault-related origin.
78
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One possible explanation is that the Kokoweef syncline represents a major
drag induced feature that formed as the southwestern wall of the fault was
displaced sinistrally with a downw ard oblique component relative to the
northeastern wall of the fault. One of the problems with this interpretation
is that the folds overturned western limb gives the syncline an asymmetric
geometry not at all consistent with a hanging wall syncline. In addition,
this interpretations fails to explain why the axis of the syncline diverges
from the fault towards the northwest.
Another possible explanation for the Kokoweef syncline is that it
represents a footwall syncline related to east-directed thrusting on a fault
just to the west of the fold. This interpretation is much more consistent
with the overturned western limb of the syncline; however, several
problems still remain. Firstly, the strange geometry of this syncline with its
widely varying axial plunge -m ost especially its localized steep to vertical
plunge- is not consistent with the geometry expected and observed in
thrust footwall synclines in the region. Furthermore, the supposed thrust
fault west of the syncline more closely resembles a splay of the K-S fault
with clear evidence for sinistral displacement. To this day the Kokoweef
Syncline remains som ewhat of a mystery and may or may not be related to
K-S faulting.
79
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Figure 33. Simplified map showing the Kokoweef Syncline in the Ivanpah
Mountains. The syncline is close and subparallel to the K-S fault.
The northwestern limb of the syncline is overturned along the
length of much of the axis. The plunge varies along strike from
nearly vertical to around 50° (from Burchfiel and Davis,
unpublished mapping).
80
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§ / q iL irts
if
ao
1 M ile
Surhcial Deposits
Penn.-Perm.
Bird Springs
Miss. M onte Cristo
Dev. Sultan
Cambrian
Bonanza King
units
Cambrian B nght Angel
Cam brian Tapeats
Proterozoic Gneiss
Fault Overturned syncline
Contact
Strike and dip of beds
y Inclined
X Overturned
/ Vertical
Strike and dip o f foliation
Inclined
Syncline
81
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Deflections w ithin the Paleozoic units
Bedding planes in the Bird Springs Formation southwest of the fault
and just northwest of Kokoweef Peak are deflected from a nearly east-west
strike to a more northwest strike as they approach the fault (Plate 1). This
deflection, if related to fault motion, would appear to indicate dextral
strike-slip motion along the fault. However, there is an alternative and
more likely explanation for the apparent fault related deflections in this
location. In this same area, a steeply northwest-plunging anticline with a
trend slightly oblique to the fault is cut by the fault. The apparent
deflection is most likely related to this fold rather than the fault (Strip B ,
Plate 1).
In another location to the southeast, just before the K-S fault is
buried beneath alluvium from Oro Wash southeast of New Trail Canyon, a
series of deflections were m apped (southern section of Strip B, Plate 1).
Beds in the Bonanza King Formation in the wallrocks southwest of the
fault have an east-southeast strike at a distance from the fault. Nearer to
the fault their strike gradually changes to a more northeasterly direction
and then very close to the fault changes very abruptly to an east-west to
east-southeast direction. This gradual large scale change in bedding
attitudes (east-southeast to northeast) is related to the Kokoweef syncline.
However the smaller scale abrupt change in strike very close to the fault
82
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may be related to K-S faulting. If so it would appear to indicate brittle
folding or buckling of bedding due to right-lateral motion on the fault
(Plate 1).
The Kokoweef fault and the gneissic foliations
Northwest of the fault bend in the Mescal Range (Strip A, Plate 1),
the K-S fault strikes west-northwest at an angle to the foliation in the
Proterozoic gneiss. Several foliation parallel traverses in the Proterozoic
gneiss northeast of the K-S fault yielded non-definitive deflection
geometries indicating both dextral and sinistral drag along the fault (Plate
1). Furthermore, the variability of foliation orientations (N45W to N-S) in
the gneiss away from the fault make it difficult to decipher true fault-
related deflections.
Dike in the New York Mountains
In the New York Mountains, about 1.5 kilometers southeast of
Slaughterhouse Spring, a dike was found that is cut and slightly offset by
the fault (Plate 2). The dike becomes altered and sheared near the fault
before terminating into the fault zone. In Bird Springs rocks the dike
appears to be deflected slightly as it approaches the fault before it is
truncated by the fault. The orientation of the dike in the west wall
carbonates changes from N55W 80SW to EW 50S as it approaches the fault.
83
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To the southeast along the fault from where the dike in the west wall is cut
by the fault, material from the dike is caught up in the fault zone where
much of it appears sheared and weathered to the point that it crumbles
away upon contact. Some intact unsheared dike material is also present
within the fault zone. Dike material is present in the fault zone for a
distance of about 75 meters and then disappears very close to where
another dike (or possibly the same offset dike) is found with a slightly
different orientation (N15W 50 SW) in the eastern wall Proterozoic gneiss.
Samples collected from the dike in both the carbonates and the gneiss are
visually identical, adding further support to the possibility that the dikes
are simply a single offset dike.
The dike displays an amount and sense of offset that is obviously
much less and opposite to the major offset on the K-S fault. For this reason
it is interpreted that the dike was emplaced after the main episode of fault
displacement and was subsequently offset by a small amount of either right
lateral or normal dip slip reactivation. The age of the dike is not known.
84
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Chapter 5: DISCUSSION
Discussion of the kinematic evidence
The Kokoweef-Slaughterhouse fault's very linear surface trace in
areas with relatively high relief coupled with exposures of the consistently
steep (avg.- 80°) southwest-dipping fault surface and bordering shear zones
indicates a nearly vertical geometry for the fault. This is also supported by
gravity data in the New York Mountains that appears to indicate a steep
and deep boundary of large lithoiogic contrast (Miller and others, 1986).
This nearly vertical geometry alone is strongly supportive of a strike-slip
origin for the fault.
Striae and slickenside data collected from the K-S fault zone are
dominated by subhorizontal to shallowly plunging (0°-30°) striae and
steeply dipping (70°-90°) slickensided surfaces. The ages of the slickensides
and striae are not well known, so they may only characterize the most
recent movement along the fault; however, the consistent subhorizontal
nature of these striae found in different locations along the entire length of
the exposed fault would seem to indicate dominantly strike-slip motion.
Also consistent with this interpretation, are near vertical tension gashes in
the fault walls at the few locations where they were found. The geometry
of the fault, the slickenside striae and, to a lesser extent, the tension gash
85
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data when taken together strongly suggest that the K-S fault has been
dom inated by strike-slip motion.
Evidence for the sense of strike-slip displacement along the K-S fault
comes from fault slivers, smaller related faults, fault-related folding,
stratigraphic deflections and gouge fabrics. Fault slivers along the K-S fault
in the Mescal and Ivanpah Ranges primarily comprise carbonate rocks
from the Permian Kaibab Formation, with lesser slivers from the Triassic
Moenkopi, Cambrian Tapeats and Cambrian Bright Angel Formations.
These slivers of material, described in the previous chapter, are interpreted
as having been sliced from the southwestern wall of the fault, and left
behind in the shear zone as the walls moved past each other. In every case,
the position of the slivers with respect to their most probable source areas
indicate minimal sinistral displacement on the K-S fault for distances up to
approximately 3.7 km (Fig. 28).
As mentioned in the previous chapter, two smaller related faults
that branch off of the K-S fault provide further evidence regarding the
main fault’ s sense of displacement. Both of these faults appear to be steep
and have surface traces that are subparallel to the main fault. Their
branching geometry along with the presence of dominantly subhorizontal
striae in the shear zones and on fault surfaces associated with these faults
appears to support the conclusion that these smaller faults are related to the
K-S fault. Stratigraphic offsets displayed by these smaller related faults in
86
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both cases aie consistent with sinistral displacement. The secondary fault
in the Ivanpah Range displays around 3.5 km of sinistral offset and
according to Miller and Wooden (1993) the splay in the New York
Mountains shows between 5 and 15 km of sinistral offset. Assuming that
the main fault has accommodated more displacement than its apparently
related splays a bare minimum displacement of 5-15 km can be assumed for
the K-S fault.
The small-localized structural domain observed adjacent to the fault
in the Mescal Range provides further evidence for the sense of shear. This
domain defined by north-vergent overturned synclines, north-trending
striae on the KP-MM thrust, and the eastward deflection of the Delfonte
syncline is interpreted as having formed as a result of interaction between
the east to northeast vergent Keaney Pass-Mollusk Mine thrust plate with
the sinistral, northwest-striking K-S fault. The synclines have a sense of
deflection and a northward vergence that appears to be most consistent
with sinistral displacement on the K-S fault during this interaction.
The locally overturned Kokoweef syncline with its fault parallel
axial trend and its variable plunge along strike may or may not provide
further evidence for the K-S faults shear sense and remains a relatively
enigmatic structure.
Geologic evidence in the New York M ountains supports an earlier
deeper phase of sinistral movement followed by an episode of smaller
87
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dextral displacement. The Mid Hill Adamellite pluton intrudes across a
sharp fault contact between Proterozoic gneiss and Bird Springs marble.
Slip along this sharp fault is responsible for juxtaposing Paleozoic and
Mesozoic rock units against Proterozoic gneiss prior to the intrusion of the
pluton. In contrast, fault gouge and a brittle shear zone that cuts across the
pluton at some localities north of Slaughterhouse Spring indicates a later
stage of more brittle deformation along the fault. The composite planar
fabric in the gouge as well as an offset dike indicate that this phase of
movement was small and dominantly dextral in nature.
It is clear that kinematic evidence exists for both dextral and sinistral
movement on the K-S fault. However, it appears that the strongest
evidence for sense of major displacement on the K-S fault comes from both
the fault slivers along it and its related secondary and splay faults. Both
types of structures provide stratigraphically related evidence that
consistently indicates sinistral displacement. Features like gouge fabrics
and small deflections along the Slaughterhouse segment of the K-S fault
are interpreted to represent only most recent activity along it.
Tectonic implications
The intra-arc location and orientation of the K-S fault and its active
displacement during Cretaceous magmatism and thrust faulting in the
foreland fold and thrust belt has important tectonic implications. Evidence
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presented in this paper indicates that the K-S fault represents a left-lateral
intra-arc strike-slip fault within a contractional arc. The K-S fault is
interpreted here as a fault related to strike-slip partitioning within the
magmatic arc. The conditions that favor strike-slip partitioning in
convergent plate margins are 1) oblique convergence, 2) a low angle of
subduction, and 3) relative thermal softening of the magmatic arc (Fitch,
1972; Beck, 1983). In these instances deformation related to convergence is
partitioned into two components: (1) contraction or extension subparallel
to the plate boundary and (2) boundary parallel shear that can be
accommodated by strike-slip faulting (Fitch, 1972; Beck, 1983; and Jarrard,
1986). According to a model proposed by Beck (1983), slip on subduction
zone parallel strike-slip faults is most favorable when the subduction angle
is around 30°, and the angle of convergence is more than 20-30° away from
perpendicular to the plate boundary. The magmatic arc is the most
favorable location for trench-linked strike-slip faulting because of the
decreased thickness of the lithosphere there as a result of heating and the
high thermal gradient (Beck, 1983; Jarrard, 1986).
Under the demands of this interpretation the left-lateral K-S fault
m ust then be related to a phase of left oblique convergence sometime
between 100.5 ± 2 Ma and -95 Ma. There is some debate regarding plate
motions during this time interval, although collective evidence from other
Cordilleran areas appears to indicate a change from either normal or
89
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sinistral convergence to dextral oblique convergence beneath western
North America at some time in the mid-Cretaceous, ca. 83 Ma (Engebretson
et al., 1985; Kelley, 1993; Kelley and Engebretson, 1994).
Evidence for sinistral oblique subduction during the 100.5 ± 2 Ma to
-95 Ma time interval is present within the North American Cordillera.
The Pine N ut fault, a major, but somewhat controversial, northwest-
striking fault active within the western Cordillera is interpreted by Oldow
et al. (1983, 1984) as a mid-Cretaceous trench-linked strike-slip fault that
decoupled deformation in the arc and back arc. In order to explain the left-
lateral Pine N ut fault, Oldow et al. (1983,1984) suggested a period of left
oblique subduction from middle or late-Jurassic to sometime around 100
Ma. Further indication of sinistral displacements during the mid-
Cretaceous along the western margin of North America is present within
the southern Coast Belt-North Cascades region and the western
Intermontane Terrane (Monger et al, 1994; Hurlow, 1993). Monger et al.
(1994) attribute the presence of a Mesozoic accretionary fore-arc complex
east of a coeval arc to pre-mid Cretaceous sinistral displacement. Structural
evidence indicates sinistral movement of mid-Cretaceous age on the
Pasayten fault in Washington as well as near the Yalakom fault in British
Colombia (Monger et al, 1994; Hurlow, 1993). S-C fabrics from a 1-km thick
mylonitic shear zone within the Pasayten fault zone consistently indicate a
sinistral sense of shear (Hurlow, 1993). The age of mylonitization within
90
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this zone is constrained between 105 ± 4 (K-Ar) and 97± 2 Ma (Rb-Sr)
(Hurlow, 1993).
The case for sinistral convergence of the North American and
Farallon plates up until ~95 Ma (or somewhat younger) is not without
problems. According to an early Farallon/N orth American plate
reconstruction model, the switch from normal or sinistral convergence to
dextral oblique convergence occurred sometime between 125 Ma and 100
Ma (Engebretson, 1985). Evidence for the presence of right-lateral intra-arc
strike-slip deformation as early as 150 Ma along the Mojave Snow Lake
fault, and as early as 105 Ma on the proto-Kern Canyon fault also appear to
support a pre-100 Ma switch to dextral oblique convergence (Busby-Spera
and Saleeby, 1990; Lahren et al, 1990 and Schweickert et al, 1990). However,
the early-Cretaceous timing (< 150 Ma) and location of the Mojave Snow
Lake fault is not at all well constrained (Lahren, 1990). Busby-Spera and
Saleeby (1990) suggest that the dextral proto-Kern Canyon fault may have
initiated as early as 105 Ma, however, the age of mylonitization along the
fault is between 85 and 83 Ma, well after the proposed sinistral episode
(Busby-Spera and Saleeby, 1990).
In support of the abundant evidence for mid-Cretaceous sinistral
displacements along the western m argin of North America, recently
derived relative motions for the Farallon and Pacific plates between 118
and 83 Ma based upon newly available relative motion parameters indicate
91
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a strong sinistral tangential component between the Farallon and North
American plates from 118 to -100 Ma (Kelley and Engebretson, 1994; Kelley,
1993). According to Kelley and Engebretson (1994) dextral displacement did
not begin until approximately 83 Ma with the interaction between the
North American and Kula plates.
The close relationship in time and space between K-S faulting and
thrust faults in the southern Cordilleran fold and thrust belt indicates that
the mid-Cretaceous arc in the eastern Mojave was in a transpressional
stress regime in which east-northeast directed thrust faulting and sinistral
arc-parallel shear were active concurrently. It appears that interactions
between these two partitioned entities in at least one location along the
fault have led to the formation of a unique local structural domain, one in
which thrusting near the K-S fault had a strong northerly component in
contrast to the regional east-northeast vergent structures.
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Chapter 6: CONCLUSION
Field m apping and the analysis of structures along the Kokoweef-
Slaughterhouse fault in the eastern Mojave Desert, California, indicate that
the dom inant episode of movement along this fault took place between
100.5 ± 2 Ma and -95 ± 2 Ma, and is best characterized as sinistral strike-
slip, possibly with a west-side down oblique component. The position of
the K-S fault within and parallel with the mid-Cretaceous arc suggests that
the fault represents an intra-arc strike-slip fault related to sinistral oblique
subduction beneath western North America. Plate reconstructions support
left lateral oblique convergence between the Farallon and North American
plates until about 100 Ma (Kelly, 1993). The nature and well constrained
timing of K-S faulting appears to suggest that this period of sinistral oblique
subduction may have persisted until at least 95 Ma. Evidence in the New
York Mountains indicates a later brittle and more shallow phase of
movement that produced a small amount of apparent dextral offset along
portions of the K-S fault. This appears to indicate later reactivation,
perhaps following the proposed switch from sinistral to dextral oblique
subduction.
93
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References Cited
Ave' Lallemant and Oldow, J.S., 1988, Early Mesozoic southward migration
of Cordilleran transpressional terranes: Tectonics, v. 7, p. 1057-1075.
Beck, Jr., M.E., 1983, On the mechanism of tectonic transport in zones of
oblique subduction: Tectonophysics, v. 93, p. 1-11.
Burchfiel, B. C., and Davis, G. A., 1971, Clark M ountain thrust complex in
the Cordillera of southeastern California: geologic summary and
field guide, p. 1-28, in Elders, W.A., ed., Geological excursions in
southern California, University of California, Riverside, Campus
Museum Contribution No. 1.
Burchfiel, B. C., and Davis, G. A., 1975, Nature and controls of Cordilleran
orogenesis, western United States: extensions on an earlier
synthesis: American Journal of Sciences, v. 275-A, p. 363-397.
Burchfiel, B. C., and Davis, G. A., 1977, Geology of the Sagamore Canyon-
Slaughterhouse Spring area, New York Mountains, California:
Geological Society of America Bulletin, v. 88, p.1623-1640
Burchfiel, B. C., and Davis, G. A., 1981, Mojave Desert and environs, in
Ernst, W. G., ed., The geotectonic development of California (Rubey
Volume 1): Englewood Cliffs, New Jersey, Prentice-Hall, p. 217-252.
Burchfiel, B. C., and Davis, G. A., 1988, Mesozoic thrust faults and Cenozoic
low-angle normal faults, eastern Spring M ountains, Nevada, and
Clark Mountains thrust complex, California, p. 87-106, in Weide, D.L.
and Faber, M.L., eds., This extended land, geological excursions in the
southern Basin and Range, Department of Geosciences, University of
Nevada, Las Vegas, 330 p.
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batholithic levels in the Southern Sierra Nevada, California:
Geology, v. 18, p. 255-259.
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the Punchbowl Fault, California: Journal of Structural Geology, v. 9,
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Fitch, T.J., 1972, Plate convergence, transcurrent faults, and internal
deformation adjacent to Southeast Asia and western Pacific: Journal
of geophysical Research, v. 77, p. 4432-4460.
94
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Fleck, R.J., Mattinson, J.M., Busby, C.J., Carr, M.D., Davis, G.A., and
Burchfiel, B.C., 1994, Isotopic Complexities and the age of the
Delfonte volcanic rocks, eastern Mescal Range, southeastern
California: Stratigraphic and tectonic implications. Geological
Society of America Bulletin, v. 106, p. 1242-1253.
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zones in the western intermontane terrane, Washington, and their
relation to the North Cascades-southeastem Coast Belt orogen:
Tectonics, v.12, p.1240-1257.
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terrane trajectories for North America and oceanic plates;
Cretaceous to present, Geological Society of America Abstracts
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plates of the Pacific basin during the last 130 million years: M.S.
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Evidence of uppermost Proterozoic to Lower Cambrian miogeoclinal
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Sierra Nevada, California: Tectonics, v. 9, p. 1585 -1608.
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Coast Belt: Their bearing on pre-mid-Cretaceous sinistral
displacements: Geology, v. 22, p. 175-178
95
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Oldow, John S., Ave' Lallemant, Hans G., and Schmidt, William J., 1984,
Kinematics of Plate Convergence deduced from Mesozoic structures
in the Western Cordillera: Tectonics, v. 3, p. 201 227.
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geological and geophysical investigation of the extension of the Clark
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California, in Fife, D.L., and Brown, A.R., eds., Geology and mineral
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Santa Ana, Calif., p. 495 404.
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and strike-slip partitioning in the Late Cretaceous sierra Nevada
magmatic arc, California: Tectonic, v. 16, p. 442-459.
96
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Strip A (Mescal Ran
Map locations shown on Fig. 2
115 ° 31 ‘ 1 5 "
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/
r n mmmmmmmmmmm
: <: TW: > 3
-> -rf! V < ^ • ♦ J 5 3 » c 5 3 » lx . '. i r
Alluvium
Delfonte Volcan
Jurassic Aztec!
Triassic Chinle
Triassic Moenk<
Permian Kaibal
Grouped Paleo|
/
Cambrian Brigl
Cambrian Tapej
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Plate 1
GEOLOGIC MAP
OF THE
KOKOWEEF-SLAUGHTERHOUSE FAULT
MESCAL AND IVANPAH MOUNTAINS
J. Brooks Ramsdell
Dept, of Earth Sciences
University of Southern California
anics (100.5 4. 2 Ma)
ec Formation
lie Formation
nkopi Formation
ab Formation
•ozoic Rocks- Bird s Prin98' Mon,e Cristo, Sultan,
Nopah and Bonanza King Formations
/
ght Angel Shale
seats Sandstone
neiss (U-Pb -1.7 Ga)
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
83
f
^ _ . Fault: arrow indicates dip
D e f i n i t e , a p p r o x i m a t e , c o n c e a l e d
— — Contacts
\
Attitudes
In e d , o v e r t u r n e d a n d v e r t i c a l b e d d i n g
n e d a n d v e r t i c a l f o lia tio n
Folds
i n c l i n e , a n t i c l i n e a n d o v e r t u r n e d , a r r o w
id i c a te s p l u n g e
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Strip B (Ivanpah
Map locations shown on
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i
Cambrian 1
Proterozoic
i Mountains)
on Fig. 2
_ ■
I
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!oic gneiss (U-Pb -1.7 Ga)
Scale 1:6000
feet
0 5 0 0 1 000 1 5 0 0 2 0 0 0 2 5 0 0
kilom eters
Portions of map taken from Burchfiel and Davis unpublished
S y n c l i n e , a n t i c l i n e a n d o v e r t u r n e d , a r r o w
i n d i c a t e s p lu n g e
lapping
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Folds
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*r
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115 °28' 45"
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NOTE TO USERS
Oversize maps and charts are microfilmed in sections in the
following manner:
LEFT TO RIGHT, TOP TO BOTTOM , W ITH SMALL
OVERLAPS
The following map or chart has been microfilmed in its entirety at
the end of this manuscript (not available on microfiche). A
xerographic reproduction has been provided for paper copies and is
inserted into the inside of the back cover.
Black and white photographic prints (17”x 23”) are available for an
additional charge.
U M I
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Plate 2
GEOLOGIC MAP OF
THE KOKOWEEF-SLAUGHTERHOUSE FAULT
NEW YORK MOUNTAINS
J. Brooks Ramsdell
Alluvium
' m j
sSx^s’ ^si-^a
Rag-phyric mafic dike
Mid Hills Adamellite
PPbs
Mesozoic metamorphosed volcanic
and sedimentary rocks
Mesozoic calc-silicates
Pennsylvanian-Permian Bird Springs
Proterozoic gneiss (U-Pb -1.7 Ga)
Fault: arrow indicates dip
D e f i n i t e , a p p r o x i m a t e , c o n c e a l e d
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Qal
PPbs
Alluvium
Plag-phyric mafic dike
Mid Hills Adamellite
Mesozoic metamorphosed volcanic
and sedimentary rocks
Mesozoic calc-silicates
Pennsylvanian-Permian Bird Springs
Proterozoic gneiss (U-Pb -1.7 Ga)
83
i
D e f i n i t e , a p p r o x i m a t e , c o n c e a l e d
Fault: arrow indicates dip
Contacts
Attitudes
I n c l in e d , o v e r t u r n e d a n d v e r t ic a l b e d d i n g
V
I n c lin e d a n d v e r t ic a l f o lia tio n
Portions of map taken from Burchfiel and Davis, 1 9 7 7
.v n ; v .Tv
as
|pisl
m l,
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/
4?
/
Scale 1 :60
1000
m iles
kilomet
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00
1 5 0 0 2 0 0 0 2 5 0 0
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(Mil!
h 111 i i i f
! i ( 1 ! ; I ! 1
’s i ; . '1;
t I s !
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; • i i i i i i q
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Asset Metadata

Creator Ramsdell, Jacob Brooks (author)

Core Title Kinematic history and tectonic implications of the Kokoweef-Slaughterhouse fault, eastern Mojave desert, California

Degree Master of Science

Degree Program Geological Sciences

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

Tag Geology,OAI-PMH Harvest

Language English

Contributor Digitized by ProQuest (provenance)

Advisor Davis, Gregory (committee chair), Paterson, Scott (committee member), Sammis, Charles G. (committee member)

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c16-31172

Unique identifier UC11337010

Identifier 1395141.pdf (filename),usctheses-c16-31172 (legacy record id)

Legacy Identifier 1395141.pdf

Dmrecord 31172

Document Type Thesis

Rights Ramsdell, Jacob Brooks

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 au...

Repository Name University of Southern California Digital Library

Repository Location USC Digital Library, University of Southern California, University Park Campus, Los Angeles, California 90089, USA