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Carbonate microfacies of the Upper Monte Cristo Limestone and the Lower Bird Spring Group at Mountain Springs, Clark County, Nevada

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Carbonate microfacies of the Upper Monte Cristo Limestone and the Lower Bird Spring Group at Mountain Springs, Clark County, Nevada

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Content CARBONATE MICR0FACIE3 OP THE UPPER
MONTE CRISTO LIMESTONE AND THE
LOWER BIRD SPRING GROUP AT
MOUNTAIN SPRINGS, CLARK COUNTY, NEVADA
by
Donald Stewart McDougall
A Thesis Presented to the
PACULTY OP THE GRADUATE SCHOOL
UNIVERSITY OP SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
MASTER OP SCIENCE
(Geological Sciences)
June 1970
UMI Number: EP58571
All rights reserved
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UMI EP58571
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789 East Eisenhower Parkway
P.O. Box 1346
Ann Arbor, Ml 48106- 1346
UNIVERSITY PARK
LOS ANGELES, CALIFORNIA 90 0 0 7
c
70
This thesis, w ritte n by
DonaId Stewart _ _M c Do ugall.......
under the direction of h..%S..Thesis Committee,
and approved by a ll its members, has been p re
sented to and accepted by the Dean of The
Graduate School, in p a rtia l fu lfillm e n t of the
requirements fo r the degree of
Master ..of. _Sc.ieja.ee................
(GeAlogJical Sciences)
'Tnx^fO
Dean
D a te MAY.2.S...197Q.
THESIS COMMITTEE
S ? s Chairman
....
f C \ 6 i t _ . \ t L _ A -
CONTENTS
Page
ABSTRACT........................................... vi
INTRODUCTION ...................................... 1
Previous w o r k ................................ 1
Purpose ...................................... 4
Location ...................................... 4
Acknowledgments .............................. 9
Generalized stratigraphy ..................... 9
PROCEDURE......................................... 14
Field procedure................. 14
Description of measured section ............. 14
elasticity................. 14
Sampling procedure ....................... 17
Petrographic procedure ....................... 20
Thin section examination ................. 20
Point Count data.......................... 21
Microfacies.................................. 22
Microfacies 0: Micrite ...................... 24
Microfacies 1: Biomicrite .................... 29
Microfacies 2: Biomicrite ............. 29
Microfacies 3: Biosparite .................... 32
Microfacies Oa: Quartz-rich micrite ......... 35
ii
Page
Microfacies la: Quartz-rich biomicrite . . • 38
Insoluble residue analysis 43 i
QUANTITATIVE ANALYTICAL TECHNIQUES 44 j
Cluster Analysis .............................. 44
Time-Trend Analysis .......................... 48
DISCUSSION OP RESULTS ............................ 56
Cluster I 56 |
i
Cluster I I 57 !
Cluster III .............................. 58
Cluster I V ......................... 59
Cluster V .................................... 60
t
Cluster V I 61 |
!
Cluster V I I .................................. 62
Time-Trend Analysis .......................... 66
BATHYMETRIC MODEL ................................ 77
Carbonate microfacies ............. ••••• 77
Quartz-rich microfacies ..................... 80
j
Succession of microfacies 81 !
i
COMPARISON WITH OTHER AREAS ..................... 83
SUMMARY AND CONCLUSIONS .......................... 86
!
REFERENCES 88 !
I
APPENDICES 93 j
APPENDIX A: Description of Stratigraphic
Column.......................... 94
iii
Page
APPENDIX B: Point Count Data Matrix 122
iv
ILLUSTRATIONS
Figure
1. Index map ..............................
2. Location of stratigraphic section . . .
3. Stratigraphic column ...................
4. Clastic log ............................
5. Relative abundance of microfacies . . .
6. Microfacies 0..... .............................................................
7. Microfacies 1 ..........................
8. Microfacies 2 ..........................
9* Microfacies 3 ..........................
10. Microfacies Oa ..........................
11. Microfacies la ..........................
12. Relative abundance of variables • • • •
13. Dendrogram ..............................
14. Time-trend curves .....................
15* Time-trend curves .....................
16. Bathymetric model .....................
Table
1. Cosine-theta similarity coefficient
matrix ..................................
Page
5
7
15
18
25
27
30
33
36
59
41
45
49
51
53
78
47
v
ABSTRACT
A detailed quantitative petrographic study was
I made of a stratigraphic section 2,260 feet (688 m) thick
[including the upper Monte Cristo Limestone and the Bird
(Spring Group to determine the depositional environment. |
The stratigraphic section includes miogeosynclinal sedi- '
ments, both carbonates and terrigenous sandstones. [
Ninety-four thin sections were point counted and I
assigned to six microfacies using a previously established |
classification. Microfacies 0 is an almost pure micrite !
with less than 3 percent biogenic grains. The abundance
of biogenic grains ranges from 3 to 30 percent in micro
facies 1 and from 30 to 50 percent in microfacies 2.
Microfacies 1 has a micrite matrix whereas microfacies 2
may have a matrix of both micrite and sparry calcite.
Microfacies 3 is a biosparite that contains more than 50
percent biogenic grains and a matrix of both sparry cal
cite and micrite. Microfacies Oa is a quartzose sand
stone whereas microfacies la is the quartz-rich equivalent j
(of microfacies 1. I
I
R-mode cluster analysis grouped 17 observed |
variables into seven clusters; five were composed of !
various organic and inorganic grains and alteration j
products, one was composed of acid insoluble variables, j
and one of carbonate matrix variables. Many of the !
organic and inorganic grains were formed in a high energy
environment and were transported to the site of deposi
tion where they occur in association with abundant
micrite. Acid insoluble variables are abundant in quart
zose sandstones and are not obviously related to the
various organic and inorganic grains. Detrital quartz,
the most abundant acid insoluble variable, is not
I related to the other organic and inorganic grains because
:it is derived from a terrigenous source whereas the other
(grains are derived from a local, intrabasinal source.
I Carbonate matrix variables sparry calcite and micrite
are not related to the other variables. Sparry calcite
was precipitated directly from sea water. Although part
of the micrite may be biogenic as suggested by studies
of Recent carbonates, the statistical results suggest
that the observed micrite is probably authigenic.
The distribution of the lithologic units with time
vi
suggests that the rocks were deposited in a miogeosyncline j
under stable and unstable conditions. The upper Monte [
Cristo Limestone was deposited under relatively stable j
conditions that produced massive, low energy micrites i
with very rare biogenic grains. After an erosional inter
val, the alternating quartzose sandstones and biomicrites
of the lower Bird Spring Group were deposited in an un
stable environment. Instability later gave way to stab
ility and energy level fluctuations diminished, resulting
in deposition of an almost unbroken sequence of micrites j
and biomicrites. i
vii
INTRODUCTION
Two units of resistant limestone exposed at j
iMountain Springs, Nevada are assigned to the Upper Monte
Cristo Limestone (Hewett, 1931). The alternating sequence j
!
of resistant limestones and non-resistant sandstones over
living the Monte Cristo Limestone is assigned to the Bird
!
iSpring Group (Hewett, 1931)* Rocks of the Monte Cristo |
Limestone are Mississippian in age, and those of the Bird
I
Spring Group are Pennsylvanian (Reade, 1962). This paper
is a detailed study of the sedimentary petrology of the
carbonates included in this sequence.
j
Previous Work j
j
| Hewett (1931) described the Monte Cristo Lime- j
stone from excellent exposures at the Monte Cristo Mine j
near Goodsprings, Nevada. Reade (1962) discussed the
stratigraphy and paleontology of the same formation at
jMountain Springs, Nevada. Hewett (1931) first described
i
and named the Bird Spring Formation from outcrops in the
iBird Spring Range, Clark County, Nevada. In a later
|
paper, Hewett (1956) investigated the Bird Spring Formation j
I in the Ivanpah Quadrangle, California and Nevada. Rich
(1961) reported on the fusulinid biostratigraphy of the
Bird Spring Formation near Lee Canyon, Clark County,
Nevada where he studied a single stratigraphic section more
2
than 7>000 feet (2,136 m) thick that ranged in age from
Chesterian to Leonardian. langenheim e_t aJL. (1962) des
cribed a section in the Arrow Canyon Range that ranged in
age from Cambrian to Permian and is about 10,000 feet
(3>045 m) thick. In this paper (Langenheim et a JL _ ., 1962),
the Bird Spring Formation, which is 3>409 feet (1,040 m)
thick, was subdivided into five units: BSa, BSb, BSc, BSd,
and BSe. Rich (1 9 6 3) published a petrographic description
of the Bird Spring Formation at Lee Canyon. He estimated
the range of percent of the various organic and in
organic components. The components were grouped as
follows: fossil groups, total skeletal grains, total
grains, autochthonous organic structures, matrix, other
allochems, and quartz. Ranges used for corals, bryozoans,
brachiopods, foraminifers, pelecypods, and echinoderms
were: less than 5> 5 to 10, 10 to 25> 25 to 50, and
greater than 50 percent of the area of the thin section.
Other biogenic grains such as sponge spicules, ostracodes,
and algal remains were estimated as greater or less than
10 percent. Autochthonous organic structures, matrix,
other allochems, and quartz were estimated as: 1 to 10,
10 to 2 5, 25 to 50, and greater than 50 percent of the
area of the thin section. Rich (1963) divided the Bird
Spring Formation into four subdivisions and recommended
that it be elevated to group status. He later published
a descriptive petrographic classification that evolved
from the study of Bird Spring carbonates (Rich, 1964).
Heath (1 9 6 5) and Lumsden (1 9 6 5) studied the lower and
middle portions, respectively, of the Bird Spring Group in j
i
the Arrow Canyon Range, Clark County, Nevada. As the work
j
done by Heath (1 9 6 5) and Lumsden (1965) was not published,
their results were later published in a paper co-authored
with Carozzi (Heath, Lumsden, and Carozzi, 196?)• The
stratigraphic section is 1,846 feet (563 m) thick and
2,095 hand specimens were collected at an average sample
interval of 10 inches (3*9 cm). Thin sections were
studied by determining the indices of elasticity and fre- j
quency of all detrital components and determining the j
frequency index of the organic components (Heath e_t al., j
1967). The thin sections were then grouped into eleven
microfacies; six normal and five quartz-rich microfacies.
The microfacies were interpreted in terms of relative
energy level and plotted alongside the stratigraphic
column* The energy level changes indicated that the Bird
i
!
Spring Group in the Arrow Canyon Range represented a |
j
transgressive-regressive sequence. Rich (1 9 6 9) published j
a detailed petrographic analysis of Atokan carbonate rocks
in the central and southern Great Basin. Several strati- j
i
graphic sections were studied and 2,300 thin sections
examined. Using the carbonate classification evolved
earlier Rich (1964) recognized nine limestone types and
related them in a hypothetical model considering environ
mental energy, relative depth, and biologic distribution.
Purpose
This study includes a detailed quantitative petro
graphic study of thin sections from the uppermost units
of the Monte Cristo Formation and the lower Bird Spring
Group. Data obtained by point counting were examined by
cluster analysis utilizing a Honeywell 800 digital com
puter. The cluster analysis performed on these data groups
the variables and relates the groups to each other to form
a hierarchy or dendrogram. Systematic variations of each
variable through the stratigraphic interval examined is
obtained by time-trend analysis. Detailed petrographic
analysis and the application of suitable statistical
techniques will contribute significantly to knowledge of
the depositional environment of the Bird Spring Group.
Location
The area is in the central part of the Spring
Mountains, Clark County, Nevada and is approximately 30
miles (48 km) southwest of Las Vegas, Nevada and may be
reached from Interstate Highway 15 by traveling west to
ward Pahrump (Pig. 1).
The stratigraphic section measured begins on a
ridge about one-half mile northwest of the community of
Mountain Springs (Pig. 2), and follows the ridge from east
Figure 1. Index map
LOCATION OF MOUNTAIN
SPRINGS AREA, NEVADA
NEVADA
LAS VEGAS
STUDY AREA
MOUNTAIN
SPRINGS
SCALE
MILES
ON
FIG. I . - INDEX MAP
Figure 2. Location of section
7
8
5 6 0 0
3 6 5 6 0 0
MOUNTAIN
SPRINGS
25
MILES TO
N
STRIKE = DUE NORTH
DIP = 36° WEST
CONTOUR INTERVAL 4 0 0 FEET
SCALE
0 I 2
MILES
FIG. 2 . - LOCATION OF SECTION
9
to west. The base of the section is in the NW l/4, SW
1/4, SE 1/4 of Sec. 18, T. 22 S., R. 58 E., San Bernardino
Base and Meridian; the top is in the NE 1/4, NW 1/4, NE 1/4
of Sec, 24, T. 22 S., R. 57 E., San Bernardino Base and j
Meridian•
: Acknowledgments |
The author thanks the following people for as
sistance in this study: Dr. R. H. Osborne, for guidance
and advice on all phases of the project; Dr. W. H. Easton,
for suggesting the topic; and Dr. R. 0. Stone for much
helpful advice in the preparation of the manuscript. j
i
Gratitude and acknowledgment is extended to R. Rodriguez
for typing the manuscript and to Alan Crawford for draft
ing of the plates. !
Generalized Stratigraphy
j
j
The strata examined are well exposed in a homocline j
that strikes due north and dips 36° W. Only 25 percent of j
the stratigraphic section is obscured by weathering. Al- j
though the section is located between large thrust faults, j
it is not faulted. The total thickness of the measured
section, 2,360 feet (720 m), begins at the top of the j
Bullion Dolomite Member of the Mississippian Monte Cristo |
j
Limestone (Reade, 1962). The lower 142 feet (43.3 m) con- |
I
sists of the Arrowhead Limestone Member, 18 feet (5.5 m) I
10 !
thick, and the Yellow Pine Limestone Member, 124 feet
i !
(37*8 m) thick, of the Monte Cristo Limestone. The Arrow- j
head Limestone Member is resistant, massive, and slightly j
fossiliferous. On fresh surfaces it is grayish-blue, I
5PB 5/2 and dark gray, N3 on weathered surfaces. All j
colors described and symbols listed in this paper refer to j
those of the Geological Society of America rock color j
|
chart (1963). The Yellow Pine Limestone Member is mas-
i
sive to thick bedded and slightly fossiliferous. On fresh I
surfaces it is medium dark gray, N4 and medium gray, N5 |
on weathered surfaces. The Monte Cristo Limestone is dis-
| i
conformably overlain by the Pennsylvanian Bird Spring j
Group (Reade, 1962). j
|
The lowermost 1,458 feet (445 m) of the Bird Spring j
Group is composed of an alternating series of fine- !
1
i
grained, resistant limestones and fine-grained, relatively
j
non-resistant quartzose sandstones. In this stratigraphic
interval the limestones range in color from dark gray, N3, !
to very light gray, N8; whereas the sandstones range from
moderate orange pink, 5YR 8/4, to grayish orange pink,
; 5YR 7/2. The limestones contain rare to abundant fossils
and the unweathered sandstones are laminated and cross
i
bedded. Immediately above the alternating limestones and
1 sandstones is a stratigraphic interval, 650 feet (198 m)
thick, composed of slightly fossiliferous, resistant
limestones that range in color from medium dark gray, N4,
to medium light gray, N6. The uppermost part of the Bird
Spring Group is a medium gray, N5> limestone that weathers
to very light gray, N8, is 110 feet (33*7 m) thick and is
very fine grained and non-resistant. The measured thick
ness of the Bird Spring Group (incomplete) is 2,218 feet
(675 m). Although the upper portion of the section at
Mountain Springs is covered by alluvium, the total thick
ness of the Bird Spring Group as calculated from the base
to the closest outcrop of the overlying Supai Sandstone
could be in excess of 7>000 feet (2,135 m).
Hewett (1931) first described and named the Bird
Spring Group from exposures in the Bird Spring Range. In
an unpublished report Girty referred the group to the
Pennsylvanian system on macrofauna collected by Hewett
(1931). In the same report Girty also mentioned the
stratigraphic section exposed at Indian Springs, approxi
mately 50 miles (80.3 km) northwest of Las Vegas. At
Indian Springs the lowermost 700 feet (214 m) is a dis
tinct lithologic unit, the Indian Springs Formation, com
posed of yellow, orange, and reddish shales interbedded
with limestone and sandstone all of which Girty (fide
Longwell and Dunbar, 1936) states is ChesterIan. The
upper boundary of this unit is gradational and is placed
arbitrarily beneath the lowest Fusulinella sp. (Longwell
and Dunbar, 1936).
In a fusulinid study of the Bird Spring Group at
12
Lee Canyon, Rich (1961) reported that the Monte Cristo
Limestone is disconformably overlain by a unit of 100 feet
(30.5 m) of quartzitic sandstone interbedded with fossili
ferous limestone and silty limestone. This unit is in
turn overlain by a sequence made up of 2,200 feet (671 m)
of fossiliferous limestone interbedded with arenaceous,
silty, and shaly limestone and calcareous shale (Rich,
1961). As microfauna are absent from the lower 515 feet
(157 m) of the section, the macrofauna was studied by
W. H. Easton (Rich, 1961). On the basis of Easton's
identifications, Rich (1961) placed the Chesterian-
Morrowan boundary at 125 1 50 feet (38.1 t 1 5.2 m) above
the base of the Bird Spring Group.
Rich (1961) further reported that Fusulinella sp.
first appears at 1,220 feet (372 m) above the base of the
Bird Spring Group. As Fusulinella sp. occurs well above
the top of the Indian Springs Formation at Lee Canyon,
future studies could demonstrate that the Indian Springs
Formation was erroneously founded on paleontologic data
and should be restricted to the lowermost quartzose sand
unit.
The lowermost portion of the Bird Spring Group at
Mountain Springs is composed of 40 feet (12.2 m) of non-
resistant quartzose sandstone overlain by 1,418 feet (432
m) of alternating quartzose sandstones and fine-grained
carbonates. As no paleontologic work: was done at Mountain
Springs, no time-stratigraphic significance may be as
cribed to the section described in this paper.
According to Longwell and Dunbar (1936) the Bird
Spring Group thickens to the .northwest in the Spring
Mountains. If the relationship of the basal units is con
sistent with the thickness of the entire Bird Spring
Group, then the lowermost 40 feet (12.2 m) of quartzose
sandstone described in Mountain Springs can be correlated
on the basis of lithology and position in the section with
the 100 feet (30.5 m) of quartzitic sandstone referred to
the Chesterian by Easton (fide Rich, 1961) at Lee Canyon.
Furthermore, it may be correlated with the Indian Springs
Formation at Indian Springs which was assigned to the
Chesterian by Girty (fide Longwell and Dunbar, 1936).
! PROCEDURE I
i I
i
Field Procedure |
; j
j
Approximately two weeks were spent in the field j
i
during the spring of 1967* In addition, several week ends !
; I
; i
during 1967 and 1968 were also required to accomplish the
field research. The stratigraphic section was measured by i
the clinometer method using a Jacob*s staff subdivided in |
feet and tenths of feet. Samples were examined in the j
i
field with a hand lens and observations were recorded con- |
cerning lithology, color, grain size, stratification,
fossil content, and secondary structures. Limestone was |
differentiated from dolomite with dilute hydrochloric j
:acid.
Description of Measured Section
The stratigraphic section is subdivided into 182
lithologic units. A complete, detailed description ap
pears in Appendix A. Figure 3 illustrates the field
!relationships in a schematic manner.
!
elasticity j
i
1
elasticity, or the amount of terrigenous sediment,
is an important part of any carbonate study. There is
little or no terrigenous sediment present in the upper
Figure 3. Stratigraphic column
15
L IT H 0 LOGY DESCRIPTION LITHOLOGY DESC R IPTIO N
Q U A T E R N A R Y
P E L L E T BIOS PARITE
BIOPE LM ICR I TE M ICRITE
BIOMICRITE
MICRITE
BIOMICRITE
MICRITE 45
MICRITE
QUARTZ BIOPELMICRITE
COVERED
BIO P E LM IC R ITE MICRITE
B IO M IC R IT E
BIOPELM ICRITE
MICRITE
BIOPELM ICRITE
37
Q UARTZ MICRITE
BIOMICRITE
BIOMICRITE
BIOPELM ICRITE
BIOS PAR ITE
MICRITE
28 MICRITE
PELMICR1T E
BIO P E LM IC R ITE
QUARTZOSE SANDSTONE
26 OA QUARTZ
B IO P E LM IC R IT E
24
0 MICRITE
'•£] Q U A T E R N A R Y A L L U V IU M “ C A LC IS ILT IT E Q U AR TZO SE SANDSTONE
FIG. 3. - S T R A T I G R A P H I C CO LUM N
part of the Monte Cristo Limestone. In the stratigraphic
j
interval from 142 feet (43 m) to 1,600 feet (488 m) the
Bird Spring Group at Mountain Springs is composed of an
;alternating sequence of carbonate and quartzose sandstone
units. In this interval there are 77 units of quartzose
sandstone that represent an aggregate thickness of 766.5
feet (234 m). These units range in thickness from 0.5
feet (0.15 m) to 48 feet (l4.6 m) and average 9.9 feet
(3.0 m). There are no terrigenous quartz units in the
stratigraphic interval above 1,600 feet (488 m). Contacts
between the resistant carbonate units and the non-
resistant quartzose sand units are often obscured by
weathering. Figure 4 illustrates the percent of terri
genous sediment in each 10 feet of the stratigraphic
section. In the stratigraphic interval from 142 feet
(43.4 m) to 1,600 feet (488 m) the quantity of terrigenous
quartz fluctuates often from zero to 100 percent of each
10 feet of stratigraphic section (Fig. 4).
Sampling Procedure
Oriented hand samples were collected at intervals
of 10 feet (3 m) and at distinct changes in lithology ex
cept where the outcrop was obscured by weathering. All
183 samples were examined in the laboratory with a stereo-
graphic microscope. Visual estimates were made of the
abundance of the various components. Upon completion of
Figure 4. Clastic log
18
THICKNESS
2200-
2000 -
1800 -
1600
----------1 -------------1 ------------ 1 -------------I ------------ 1
20 40 60 80 100
P E R C E N T C L A S T IC S / EACH 10 FE E T OF SECTION
T E R R IG E N O U S Q U A R T Z FACIES
□ CA R B O N A T E FACIES
DISCON FORMITY B ET W E EN MONTE CRISTO LIMESTONE AND BIRD SPRING GROUP
FIG. 4 - CLASTIC LOG
I this phase of the work, 50 samples were chosen for thin
section analysis. Of these, four were from the Monte
Cristo Limestone and the remainder from the Bird Spring
Group. These samples were chosen to be as evenly spaced
I
as possible in order to eliminate bias from the sampling
i procedure and to facilitate a time-trend study. The
;interval between thin section samples ranged from 30 feet
(9.1 m) to 120 feet (36.8 m) and averaged 40 feet (12.2 m).
Petrographic Procedure
Thin Section Examination
After the samples were chosen, two standard petro
graphic thin sections (25 x 45 mm) were made for each of
i
the 50 samples. Two thin sections were made from each
!sample so that the intrasample variation could be
examined. Thin sections were oriented with the long
dimension normal to the bedding. They were ground to a
thickness slightly greater than the normal 0.03 mm to
allow better contrast among components.
The thin sections were analyzed by point-counting,
which quantitatively samples the area percent of the
variables included in the thin section. It was assumed
that the area percent approximated the actual volume per
cent of the variables in the sample (Chayes, 1956). It
was found that 350 points had to be counted on each thin
21
section to insure a 5 percent reliability and a 95 percent
i 1
confidence level (Van der Plas and Tobi, 1965)* A 1 mm-
square grid was used so that the point-distance was nearly
always greater than the largest particle diameter included
in the thin section* In order to reduce bias in the j
point-counting procedure, the starting point on the grid
was determined using a random numbers table (Fisher and
Yates, 1963).
j
Point-counting Results |
The point-counting results are tabulated in Ap
pendix B. These data are the number of points counted for
I
each variable. For each variable measured the value was
jthen converted to a weighted percent score. The highest
i i
i
value obtained for each variable was made equal to 100 |
percent. This was done so that each variable would be
given equal weight in the quantitative analysis. The
weighted percent scores for each variable were then
averaged for the A and B thin sections obtained from each j
I
hand specimen. These data were termed the weighted average j
percent scores. j
i
The primary objective of this study is to deter
mine the depositional environment of the Bird Spring Group |
in the study area. Many thin sections, however, show |
evidence of secondary alteration. In all but two thin
sections micrite is, in part, altered to sparry calcite,
dolomite, or chert. In some cases sparry calcite and
crinoid columnals are altered to dolomite and the centers
of a few faecal pellets are altered to quartz. Where pos
sible, the altered components are treated as the inferred
primary component in the quantitative analysis. Primary
'components cannot he inferred due to intense alteration
in six thin sections.
Microfacies
Many researchers in the field of carbonate
petrology have erected their own classifications, and some
have introduced descriptive terms that may or may not have
meaning to other researchers. As a result, the literature
is replete with classifications and descriptive terms of
|questionable value. Previous investigators have published
i
:classifications based on the carbonates of the Bird Spring
Group. Rich (1964) published a descriptive classification
that evolved from a study of Bird Spring carbonates at
Lee Canyon, Nevada. Although adequate for his purpose,
;Richfs (1964) classification was based on visual estimates
of the abundance of variables and does not lend itself to
a quantitative study.
Heath ejt al. (1 9 6 7) made an exhaustive, quantitative
study of the Bird Spring Group in the Arrow Canyon Range
approximately 70 miles northeast of Mountain Springs. The
classification of Heath et al. (1 9 6 7) was used in this
23
study because of its quantitative nature, proximity to
Mountain Springs, and a desire on the part of the writer
not to contribute another classification to an already
complex literature.
The portion of the Monte Cristo Limestone examined
for this study is composed primarily of calcilutite with
minor amounts (less than 3 percent) of scattered biogenic
grains including brachiopods, crinoids, algae, and faecal
pellets. The calcilutite contains less than 3 percent
insoluble residue. The lower part of the Bird Spring
Group is an alternating sequence of calcilutites and
!
quartzose sandstones. Disseminated biogenic grains and up
to 10 percent detrital quartz are present in the calcilu- j
tites. Quartz grains in the sandstone units are rounded j
and appear well sorted in thin section. The upper segment j
i
of the Bird Spring Group is calcilutite that contains only !
a few disseminated biogenic grains and less than 3 percent
detrital quartz.
On the basis of the relative abundance of micrite,
organic debris, and detrital quartz, the samples are as
signed to six carbonate microfacies recognized by Heath
et al. (1967). The samples are divided into two groups:
a normal and a quartz rich. There are four microfacies,
numbered zero to three, in the normal group and two micro-
!
facies, Oa and la, in the quartz-rich group. Samples in j
the normal group have less than 10 percent detrital quartz \
and comprised 92 percent of the samples examined petro-
I j
igraphically. In the field, however, the normal group j
I !
represents only 70 percent and the quartz-rich group 30 j
percent of the stratigraphic section. Units that are as- j
signed to the quartz-rich group are relatively non- !
resistant and difficult to sample. The relative abundance
|of the 6 microfacies is illustrated in Figure 5-
j
Microfacies 0: Micrite J
| !
I j
In megascopic aspect this microfacies is very fine- !
j
|grained, resistant, and massive to thick bedded. Fresh
i
surfaces are dark gray, N3» to medium gray, N5» whereas
weathered surfaces are very light gray, N8. Rocks of |
this microfacies sometimes weather in a steplike manner, !
j
the ,fstepsn ranging in size from 1 foot (0.3 m) to 2 feet i
I j
; (0.6 m).
i
In microscopic aspect this microfacies is an al
most pure micrite with less than 3 percent organic debris
(Fig. 6). The groundmass is light to dark brown crypto-
;crystalline calcite that may be partially recrystallized
to clear sparry calcite. The brown color may be caused by
included organic matter. Detrital quartz grains are rare.
Abundant biogenic grains include faecal pellets
and fragments of brachiopods and crinoids, whereas isolated
fragments of bryozoans, fusulinids, trilobites, and
;ostracodes only rarely occur.
Figure 5* Relative abundance of microfacies
25
PERCENT OF THIN SECTION SAMPLES
FIG. 5. ~ RELATIVE ABUNDANCE OF MICROFACIES
Figure 6 Microfacies 0 (Sample 47). Micrite
partially recrystallized to sparry
calcite. Hicols uncrossed X28.
27

29
Microfacies 1: Biomicrite
In the field this microfacies appears as units
that are dark gray, N3> and weather to medium light gray,
N6. The units are very fine grained, resistant, and
massive to thick bedded.
In microscopic aspect the matrix is light to dark
brown cryptocrystalline calcite that may be partly re
crystallized to clear sparry calcite in small spots on the
thin section (Pig. 7). All sparry calcite observed in
microfacies 1 is considered to be primary. This micro
facies is mud supported and contains from 3 to 30 percent
biogenic grains.
The most abundant bioclasts are crinoid columnals,
echinoid spines and fragments of pseudopunctate brachio-
pods. There are minor amounts of ostracodes, fusulinids,
and arenaceous benthonic foraminifers. Biogenic grains
show no apparent preferred orientation. Scattered quartz
is abundant in some samples. Red spots of hematite are
rare whereas veins of secondary calcite are more abundant.
Microfacies 2: Biomicrite
In megascopic aspect, this microfacies is fine to
medium grained and appears medium light gray, N6, on
weathered surfaces in contrast to fresh surfaces which are
dark gray, N3- The units included in microfacies 2 are
Figure 7* Microfacies 1 (Sample 20). Bio
micrite containing crinoid columnals
and fusulinids. Micrite has partial
ly recrystallized to sparry calcite.
A vein of calcite transects the
fusulinid specimen. Nicols un
crossed X28.
30
31
3 2 j
massive to thick bedded and resistant.
In thin section microfacies 2 is a biomicrite
(Fig. 8). A few samples are grain supported and several
are mud supported. The matrix is light- to dark-brown
i
micrite which may be partially recrystallized to clear
!
sparry calcite up to 47 percent. Primary spar is also !
present up to 14 percent and fills the interstices between
faecal pellets. Sparry calcite is considered to be
primary when it encrusts allochems in radial fringes !
i
(Folk, 1962) and secondary when it contains dark spots of j
unaltered micrite.
1
Biogenic grains range from 30 to 50 percent. Some
1
samples contain abundant (35 percent) faecal pellets
which are circular to elliptical and have no characteristic !
1
1
internal structure.
Faecal pellets are the most abundant biologic i
i
component, followed by crinoid columnals and echinoid
spines. This microfacies also contains minor amounts of
ostracodes, fusulinids, and brachiopod fragments.
There is no obvious preferred orientation of the j
biogenic debris. j
|
Microfacies 3: Biosparite j
In the field this microfacies is fine to medium I
grained. On both fresh and weathered surfaces it is
medium gray. Units included in microfacies 3 are massive
Figure 8. Microfacies 2 (Sample 14). Pellet
biomicrite. Mud-supported. Micrite
has partially recrystallized to
sparry calcite. Nicols uncrossed
X28.
33
34
35
| to thick "bedded and contain small veins of secondary cal-
i
cite.
In microscopic aspect, microfacies 3 is a grain-
supported biosparite (Fig. 9). The matrix is light-brown
cryptocrystalline micrite and clear sparry calcite.
Micrite ranges from 7 to 25 percent and appears in small
pockets trapped between grains. Sparry calcite ranges up
to 49 percent and appears as radial fringes encrusting
biogenic grains.
Faecal pellets, crinoid columnals, and echinoid
spines are the most abundant biogenic grains. Faecal
pellets comprise up to 60 percent. A few of the crinoid
columnals are recrystallized to dolomite. There are also
j
;minor amounts of ostracodes and arenaceous benthonic fora-
miniferida.
Microfacies Oa: Quartz-rich Micrite
In megascopic aspect this facies is a sandstone
that is resistant to non-resistant and ranges in color
from moderate orange pink, 5YR8/4, to grayish orange pink,
5YR7/2. Resistance to weathering apparently depends on
the abundance of calcite cement. Quartzose units that
i
contain only minor amounts of calcite are non-resistant
and weather in place to a sandy soil. Units that contain
more than 50 percent calcite cement are resistant. These
units are generally well exposed and display laminae and
Figure 9* Microfacies 3 (Sample 32). Grain-
supported biosparite. Biogenic
grains include faecal pellets,
echinoid spines, and crinoid
columnals. The large faecal pellet
near the center has partially re
crystallized to sparry calcite.
The matrix is sparry calcite with
small amounts of micrite. Nicols
uncrossed X28.
36
37
V* *v h ;
I 38 !
i
i i
;cross-beds. ;
j
| Thin section samples of this microfacies show j
quartz grains that range in size from fine sand to silt j
(Pig. 10). Individual grains are rounded and appear well |
| |
sorted. Laminae are evident in some thin sections and ab-
i
;sent in others. Isolated spots of hematite are present in |
|the more weathered samples.
Of the 48 samples observed in thin section only 3
{represent microfacies Oa. However, it seems likely that
i
77 of the 182 field units represent microfacies Oa because
of similarity in color and because they weather to form a
j
sandy soil. j
Microfacies la; Quartz-rich Biomicrite
In outcrop, microfacies la is fine grained,
'laminated and contains more than 10 percent detrital quartz.
It is medium dark gray, N4, on fresh surfaces and medium
!light gray, N6, on weathered surfaces.
In thin section the rock is mud supported (Pig.
ill). The matrix is light- to dark-brown micrite. The
|abundant detrital quartz grains, a small number of which
1
are covered by a light brown iron oxide stain, are rounded
j and fairly well sorted.
! Biogenic grains range from 3 to 30 percent. The
dominant biogenic grains are faecal pellets, crinoid
i
columnals, and echinoid spines. Bryozoan fragments are
Figure 10. Microfacies Oa (Sample 26).
Quartz-rich, micrite. Most of the
slide area consists of silty
quartz grains. The quartz grains
are rounded and appear well sorted.
Cement is micrite. Laminae,
visible in hand specimen, are not
visible in thin section. Nicols
uncrossed X28.
39
40
Figure 11. Microfacies la (Sample 18).
Quartz-rich biomicrite. Quartz
grains are silt sized, rounded,
and well sorted. Biogenic
grains include faecal pellets
and crinoid columnals. Oolites,
as in the upper left quadrant,
are rare. Micrite has partially
altered to sparry calcite.
Nicols uncrossed X28.
41
42
43 |
! |
jrare. Some of the crinoid columnals are recrystallized to j
|dolomite.
; Both the quartz and the biogenic grains appear in
i
jwell-defined laminae in thin section.
I
j
I
| Insoluble Residue Analysis
i
j
j All of the samples chosen for thin section analysis
were also analyzed for insoluble residue. Approximately
25 grams of crushed sample was dissolved in 10 percent
hydrochloric acid (3.1 Molar). The residue was then
dried, weighed, and the weight percent of insoluble
residue calculated.
1
; Data concerning the weight percent of insoluble
!
Iresidue are tabulated in Appendix B.
I QUANTITATIVE ANALYTICAL TECHNIQUES
i
Point counting produces a great quantity of data, j
i j
|therefore, techniques are needed to determine relation- !
j
ships among the observed variables and to determine rela- !
tive changes for each variable with respect to time. An |
appropriate form of cluster analysis may be used to deter- j
mine relationships among variables or samples whereas
;time-trend analysis illustrates changes for each variable ;
with respect to time (Harbaugh and Merriam, 1 9 6 8).
1 i
I
Cluster Analysis j
j
The initial step was to express the relationship !
i
ibetween each pair of variables as a similarity coefficient. |
j !
A cosine-theta similarity coefficient was chosen because !
|of the reduced effects of nonlinear data. Although 23
'Variables were recognized and counted in thin section,
only 16 of these were meaningfully related (R. H. Osborne,
personal communication, 1968). These variables and data
;from the study of insoluble residue were included in the
quantitative work. The variables that were point counted
1
were arranged in order of abundance and compiled in Figure
1
12. The similarity coefficients for the variables of the
Monte Cristo Limestone and the Bird Spring Group were
!
tabulated in a symmetrical matrix (Table I). Cluster
analysis was performed on the 17 variables that appear in
Figure 12, Relative abundance of variables
45
OOLITES
SPONGE. SPICULES
INTRACLASTS
OSTRACODES
HEMATITE
BRYOZOANS
BRACHIOPODS
CHERT
ECHINOIDS
ALGAE
DOLOMITE
CRINOIDS
SPARRY CALCITE
DETRITAL QUARTZ
P E L L E T S
MICRITE
2 3 4 5 80 6 1 82 83
PERCENT OF TOTAL POINTS COUNTED
FIG. 1 2 . - RELATIVE ABUNDANCE OF VARIABLES
/
/ /
A
0T? o * / J?
c/ < ^ y o
J * S / ’
& 4? i
/ / / / / / / / / / / ■ '
1 2 3. 4. 5. 6 . 7. 8 . 9. 10. II. 12. 13. 14. 15. 16. 17.
ALGAE 1 1 .000
0RACHIOPODS 2. 0.271 1.000
8RY0Z0ANS 3. 0.611 0.488 1.000
CRINOIDS 4 0.262 0119 - 0.017 1.000
ECHINOIDS 5. 0.387 0.237 0 .0 3 6 0 .8 4 3 1.000
OSTRACODES 6. 0.148 0.167 -0 . 0 6 2 0.707 0 .7 0 7 1.000
SPONGE SPICULES 7. 0 091 0 134 0 .0 3 6 0.175 0 .2 9 4 0 .0 5 9 1.000
DETRITAL QUARTZ 8. -0.108 -0.150 - 0.038 - 0 .0 9 7 -0 .0 6 2 0.110 0 .0 6 3 1.000
INTRACLASTS 9 0.116 0 108 0 .0 3 6 0.162 0.097 -0.108 0.522 -0 .0 4 8 1.000
PELLETS 10. 0.2 0 4 -0 .0 5 2 -0 .0 2 2 0.093 0 183 0.083 0.200 -0 . 0 7 4 - 0,0 0 3 1.000
OOLITES II. 0.623 0.377 0 .9 0 4 0 .0 9 4 0.077 -0.015 0.081 - 0 . 0 5 5 - 0.0 3 7 0 .0 2 5 1.000
M 1C RITE 12. -0 . 4 9 8 -0.103 -0 .1 0 3 - 0 .4 7 9 -0 .3 8 4 -0 .1 4 4 - 0.193 0.4 5 5 - 0.193 -0 .2 3 6 - 0 .4 7 0 1,000
SPARRY CALCITE 13. 0.490 0 .0 5 9 0.450 0.515 0 .4 4 3 0.239 - 0.096 - 0 .0 7 7 - 0.0 4 9 -0.01 8 0.480 0.682 1.000
OOLOMITE 14. 0.613 0.443 0 .9 8 8 - 0 . 0 5 0 -0 .0 3 5 - 0 . 0 9 4 - 0.041 - 0 . 0 * 3 - 0.013 -0 .0 7 3 0.920 -0 . 4 5 0 0.465 1 .0 0 0
CHERT 15. 0.113 0.087 0.039 0.171 0.150 - 0 .0 8 9 0.521 - 0 .0 4 4 0.9 9 4 -0 .0 7 2 - 0 . 0 3 0 -0 .2 0 3 -0 . 0 4 5 -0.012 LOOO
HEMATITE 16. - 0 0 8 0 -0.15 0 - 0 .0 3 3 - 0.083 -0 .0 9 8 -0 .1 0 3 - 0.061 0.819 0 . 0 2 8 , - 0 .0 7 9 -0 .0 3 0 -0.41 9 -0 . 0 4 7 - 0 . 0 2 5 - 0 . 0 2 6 1.000
INSOLU8LE RESIOUE 17. - 0.1 7 * -0 .1 6 5 - 0 .0 7 9 - 0.150 -0.153 -0.122 0.104 0.687 0.101 - 0 . 2 0 9 -0.110 -0 .1 9 7 -0.154 - 0 . 0 8 4 O.liO 0 .6 0 0 1.000
TABLE 1 . - COSINE - THIiTA SIMILARITY COEFFICIENT MATRIX * j
j
' . . • • i
• > -A te '
; T;. , , - '• • • . , , . ■ '
• . -• v> ■ 1 " " -F ~ i * * , " I: !■ rj 1 . -■ / ^ r' _ x, ' -V '
48
Table I using Spearman*s sums of variables formula (Sokal
and Sneath, 1963). Spearman's sums of variables formula
(Sokal and Sneath, 1963) used the correlation coefficients
of Table I to group the variables and construct a dendro
gram (Fig. 13). j
Time-Trend Analysis
Time-trend analysis is used to illustrate changes
in the abundance of each variable with respect to time.
Time-trend curves were plotted from the weighted average
percent scores utilizing a Honeywell 800 digital computer
to smooth the curves. Vistelius (1961) defined smoothing j
as changing a series of values with irregular finite dif
ferences into a series of values with regular differences.
Smoothing techniques may be used to enhance short-period !
or long-period fluctuations in abundance. The Spencer
21-term smoothing equation, discussed by Harbaugh and
Merriam (1968) was used for each variable and the results
plotted after the first and the tenth smoothing operation, j
The long-period smoothing technique was used on the Bird j
Spring carbonates as the inter-sample distance ranged from i
i
30 feet (9.1 m) to 120 feet (36.6 m) and averaged 40 feet
(12.2 m). An intersample distance of 40 feet was judged j
too large to adequately express short-period fluctuations !
I
in abundance. Time-trend curves for 14 of the 17 variables
were drawn in Figures 14 and 1 5. Three variables (dolo-
Figure 13 Dendrogram showing relationships
of observed variables.
49
+ .9_
I-
Z + .5
UJ
o
iz +- 4
Ll _
LU
O +.3
o
z + -2
O
_l
LU
c r 0
i r
o
° -.1
CLUSTER
CLUSTER VI
CLUSTER VII
CLUSTER IV
CLUSTER
CLUSTER
CLUSTER V
- .2_
FIG. 13.- DENDROGRAM
VJI
O
Figure 14. Time-trend curves
51
THIC KNESS
2200
2000
I 800
1600
400
1200
1000
800
600
400
200
20 40 60 80 20 40 60 80 20 40 60 80 20 40 60 80 20 40 60 80 20 40 60 80
BRY0Z0ANS OOLITES
W EIG HTED P E R C E N T
ALGAE BRACHIOPODS INTRACLASTS SPONGE
SPICULES
D IS C O N F O R M IT Y BETW EEN MONTE CRISTO LIMESTONE AND BIRD SPRING GROUP
RAW DATA SMOOTHED ONCE
------------- F IN A L S M O O T H E D C U R V E
FIG. 1 4 . - T IM E -T R E N D CURVES
LD
ro
Figure 15. Time-trend curves
53
THICKNESS
2200-'
1800
1600-
400
1200
1000
600
400
20 40 60 80 20 40 60 80 20 40 60 80 20 40 60 80 20 40 60 80 20 40 60 80 20 40 60 80 20 40 60 80
ECHINOIDS CRINOIDS
WEIGHTED P ER CENT
OSTRACODES PELLETS DETRITAL
QUARTZ
INSOLUBLE SPARRY
RESIDUE CALCITE
MICRITE
DIS CO NFO RM ITY BETWEEN MONTE CRISTO LIMESTONE AND BIRD SPRING GROUP
RAW DATA SMOOTHED ONCE
FINAL SM O O THED C U R V E
FIG. 15 - TIME-TREND CURVES
mite, chert, and hematite) were not sufficiently abundant
to justify the necessary computer time.
The time-trend curves of Figures 14 and 15 depict
only the point count data. There are many weathered sand-
i
stone units in the lower 1,450 feet (442 m) of the Bird
|
! Spring Group (Fig. 4) that do not appear in the point
j
i
i counts and therefore are not illustrated by the time-trend
curves. Time-trend curves for the carbonate variables are
extended across the stratigraphic intervals occupied by
the weathered sandstone units in an effort to provide con
tinuity to the curves and facilitate the expression of
trends.
56
DISCUSSION OP RESULTS
Cluster I |
j
The variables of Cluster I (Pig. 13) represent j
moderate to relatively high energy. Dolomite, bryozoans,
oolites, algae, and brachiopods together account for almost j
3 percent of the total points counted in the thin section
study. In spite of being a product of secondary altera
tion, dolomite appears in the point counts because the
primary variable could not be identified with certainty.
Dolomite and bryozoans are highly correlated (Pig. 13)
primarily because of their association in sample 10 a j
grain-supported biosparite. In this sample the dolomite
is believed to be altered sparry calcite. Both dolomite
and bryozoans are rare throughout the stratigraphic
section but both are most abundant in sample 10. The j
bryozoans are thick branched and broken around the margins, j
|
According to Duncan (1957)> bryozoans require sunlight, j
l
slightly agitated water, and a firm substrate for larval j
attachment. Bryozoan breakage may be due to high energy |
i
during deposition or to compaction during diagenesis.
Breakage in grain-supported samples is probably more likely
than in mud-supported samples and the variables of Cluster
I are more abundant in grain-supported samples. Oolites
appear in only five thin sections and are usually inter
57
preted as indicators of high energy (Newell and Rigby,
1957). Algae are present in 45 thin sections and occur as
biogenic fragments and as coatings on biogenic grains.
There is no evidence such as algal biolithites to suggest
that algae lived at the site of deposition. Brachiopods
j
appear only as broken, disarticulated fragments and al
though rare are found in 47 thin sections. When in a bio-
sparite like bryozoans, they could indicate high energy at
or before deposition, or breakage during diagenesis.
j
i
Cluster I is heavily dependent on sample 10, a grain-
supported biosparite, located approximately 400 feet (122
m) above the base of the stratigraphic section (Pig. 14)
in which all the variables are most abundant. Sample 10, |
more than any other sample, suggests that the variables of |
i
Cluster I represent moderate to relatively high energy at
the site of deposition. Because the variables of Cluster j
I are heavily dependent on one sample, it is believed that |
their association in Figure 13 has little significance in |
an interpretation of the depositional environment of the j
i
entire stratigraphic section.
i
Cluster II
Chert, intraclasts, and sponge spicules are the
I
variables of Cluster II (Fig. 13) which together account !
for less than 1 percent of the total points counted. Chert j
is found replacing Chaetetes sp. and as nodules up to 1 j
foot (0*30 m) in diameter. Like dolomite, chert appears
i
iin the point counts only when the primary variable could
not be identified. The association of chert with intra
clasts and sponge spicules is believed to be fortuitous.
Intraclasts are composed of micrite and have no internal
structure. Sponge spicules are calcified and monoaxonic.
|Because the variables of Cluster II are rare and their
association is believed to be fortuitous, they have little
or no environmental significance.
Cluster III
The variables of Cluster III, echinoids, crinoids,
and ostracodes (Fig. 13) are allochthonous and represent
moderate energy in the source area or moderate transportive
energy. Together they account for almost 3 percent of
the total points counted in the thin section study.
■Echinoids occur in 47 of the 94 thin sections and appear
as broken spines in a micrite matrix. There is no evi
dence to suggest that echinoids are indigenous. Accord
ing to Cooper (1957), echinoids indicate near shore
turbulent water. Crinoids represent almost 2 percent of
i
the total points counted and are found in 57 thin sections.
! They appear only as columnals in a micrite matrix. There
is no evidence, either in the field or in thin section,
to suggest that crinoids lived in the environment of
deposition. Laudon (1 9 6 7) stated that crinoids are found
59
in agitated, aerated water. LaPorte (1 9 6 9) finds Devonian
pelmatozoans most abundant in a high and low energy sub-
tidal environment and less abundant in a low energy open
shallow shelf environment. Ostracodes appear as scattered i
fragments in a micrite matrix in 27 of the 94- thin sections;
I
1
They are present in marine, brackish, and fresh water and j
may be either benthonic or planktonic (Agnew, 1957). La
Porte (1 9 6 9) states that ostracodes are cosmopolitan.
Similarity in ecology, a lack of whole fossils, and a
micrite matrix indicate that the variables of Cluster III
are allochthonous and represent moderate energy in the
j
source area and moderate transportive energy. j
Cluster IV
Pellets represent deposition in a low energy
i
environment such as a tidal flat or lagoon. The only
variable of Cluster IV, pellets account for almost 4 per
cent of the total points counted and are found in 47 of j
the 94 thin sections. Pelecypods, gastropods, and worms j
all produce faecal pellets (Newell and Rigby, 1957). As
fossil pelecypods were not seen in outcrop or in thin
i
section and only one fossil gastropod was noted in thin
section, the pellets, therefore, may be worm faecal
pellets. Newell and Rigby (1957) found faecal pellets in
i
areas of stabilized, grassy bottoms on the Great Bahama
Bank. LaPorte (1969) reports pellets in a tidal flat- !
60
lagoon facies in Devonian Helderberg Group carbonates. In
a study of epeiric clear water sedimentation, Irwin (1 9 6 5)
states that faecal pellets are found in low energy environ
ments landward of the surf zone. The pellets observed in
the carbonates of the Bird Spring Group probably represent
deposition in a low energy environment such as a tidal flat
or lagoon.
Cluster V
The variables of Clusters I, II, III, and IV are
combined in Cluster V at a low correlation value (Pig.
13) which infers they are essentially independent. In
Cluster V (Fig. 13) this means that the variables repre
sent different energy levels and may be derived from dif
ferent sources. Although heavily dependent on one sample,
the association of variables in Cluster I portrays
moderate to relatively high energy at the site of deposi
tion. Cluster II is believed to be a fortuitous associa
tion. The allochthonous variables of Cluster III repre
sent moderate energy at the source area and/or moderate
transportive energy. Cluster IV denotes authochthonous
deposition in a low energy environment. From this brief
discussion it Is easily understood why Clusters I, II,
III, and IV are essentially independent.
61
Cluster VI
Cluster VI (Fig. 13) is composed of the acid j
insoluble variables hematite, detrital quartz, and insolu
ble residue which together account for approximately 3
percent of the total points counted. Hematite appears in
7 of the 94 thin sections as a red-brown coating on
detrital quartz grains. It only appears in association
i
with detrital quartz which explains the high correlation
between the two variables (Fig. 13). Detrital quartz, by
far the most abundant of the acid insoluble variables, is
i
fine grained, rounded, and appears well sorted in thin !
section. Values for insoluble residue in the 48 samples !
range from 1.4 percent to 91.8 percent by weight. A brief |
visual inspection of the residue shows that it includes
chert and very fine-grained detrital quartz. ;
Cluster VI is clustered with the other variables of
the study at a low correlation value (Fig. 13) because the j
i
acid insoluble variables are derived from a different
source. There is no detrital quartz in the samples from
the Monte Cristo Limestone. Units of the Bird Spring j
Group observed in the field can be subdivided into a j
carbonate facies and an acid insoluble or terrigenous j
facies. The carbonate facies is comprised of micrites and I
biomicrites with minor biosparites and the terrigenous j
facies chiefly of detrital quartz but with minor amounts
of hematite. In the thin section study there are only 4___|
62
samples that contain more than ten counts of detrital
quartz, however, in the field there are 77 units of
weathered sandstone totaling 762.5 feet (232 m) that are
virtually impossible to sample for thin section study.
The source of the detrital quartz is believed to be the
Antler orogenic belt, a highland west of the Bird Spring
basin (Rich, 1 9 6 9). Acid insoluble variables are essen
tially independent of the other variables (Pig. 13) be
cause they are derived from a terrigenous source. Most
of the other variables are either chemically or bio
chemically produced carbonates of highly local origin.
Cluster VII
Cluster YII (Pig. 13) is composed of the carbonate
matrix variables sparry calcite and micrite which to
gether account for more than 85 percent of the total
points counted. Sparry calcite appears in 13 of the 94
thin sections but is abundant (14 to 42 percent) in only
8 thin sections. Micrite, the most abundant variable, is
ubiquitous and ranges in abundance from 7 to 100 percent.
The sparry calcite in the point count data matrix
(Appendix B) is believed to be primary as it exhibits
radial fringes around allochems (Polk, 1962). It is
important to distinguish between primary and secondary
sparry calcite as primary sparry calcite indicates cur
rents powerful enough or persistent enough to winnow away
micrite (Polk, 1962). Many thin sections examined for
this study contain abundant sparry calcite that is be
lieved to be secondary because it contains dark inclusions
|
of unaltered micrite. Secondary sparry calcite is tabu- j
lated in the point count data matrix (Appendix B) under !
I
j i
the interpreted primary variable. j
! Micrite may be organic or inorganic or both. The |
|
micrite observed in the samples from Mountain Springs may
be partially organic or biogenic but is believed to be
dominantly inorganic or authigenic. In a recent study of
Alacran Reef, Hoskin (1963) states that the micrite he
observed is biogenic, that is, derived primarily from com- j
minution of skeletons by organisms and by waves and cur-
i rents. Biogenically derived micrite should contain a
gradation in grain size from relatively large biogenic
i i
grains■to material with no discernible grain size. The |
’ samples from Alacran Reef exhibit a gradation in grain i
size whereas the samples from Mountain Springs do not. j
i
The samples from Mountain Springs contain large biogenic j
grains in a micrite matrix. As there are no whole fossils
, or biolithites to suggest that the biogenic grains are
autochthonous, they must be allochthonous. The alloch-
thonous biogenic grains were broken in a relatively high
energy environment and transported, probably down the
depositional dip, to a low energy, micrite-rich environ
ment (Irwin, 1965). LaPorte (1 9 6 9) reports micrite-rich
64
samples in microfacies that represent an open, shallow
shelf environment "below wave "base. The lack of gradation
in grain size could "be caused by selective bypassing of
the finer biogenic grains. According to Hjulstrom (1939)
a bimodal sample may be caused by selective bypassing of
sand-sized grains because they have a lower critical
velocity than either silt and clay or coarse sand.
Selective bypassing cannot account for the abundance of
micrite observed in the Mountain Springs carbonates. Bio-
genically derived micrite would be related closely to the
biogenic grains. Figure 13 shows that micrite is essen
tially independent of the biogenic grains and may, there
fore, be authigenic. Examination of Figure 12 shows that
micrite is much more abundant than all the identifiable
biologic variables together. The absence of a gradation
in grain size between micrite and biogenic grains, the
absence of a positive correlation between them, and the
relative abundance of micrite and the relative scarcity of
biogenic grains all indicate that the micrite observed in
the Mountain Springs carbonates is dominantly authigenic.
The carbonate matrix variables, sparry calcite and
micrite are moderately correlated (Fig. 13) because
micrite is ubiquitous and, therefore, whenever sparry cal
cite is present it is in association with micrite. A high
correlation between micrite and sparry calcite could easily
be explained if the sparry calcite is recrystallized
: 6 51
micrite. However, the sparry calcite appears as radial
!fringes around allochems which suggests it is primary |
i
|(Folk, 1962). There are four samples in the Bird Spring j
I
Group that contain abundant (14 to 42 percent) sparry j
calcite and also contain from 7 to 51 percent micrite.
These samples represent deposition under moderate energy j
|(microfacies 2 and 3) in which micrite was incompletely j
winnowed. In an R-mode factor analysis of Cincinnatian s
■limestones, Osborne (1 9 6 7) reported micrite in association j
i
with diagenetic sparry calcite which formed in cavities |
:under biogenic grains after the sediment attained a fair
degree of firmness. Cincinnatian limestones studied by
i
Osborne (1 9 6 7) also represent deposition under low to !
I
i
moderate energy as do the carbonates at Mountain Springs. j
Sparry calcite is moderately correlated with micrite be- j
cause both are matrix variables and micrite is ubiquitous
; owing to incomplete winnowing.
The carbonate matrix variables of Cluster VII j
I
(Fig. 13) essentially are independent of the other
I variables because they are derived from seawater either as
sparry calcite or as micrite. Many of the variables of
Clusters I, II, III, and IV are either biogenic or in
organic grains and are derived from a carbonate terrain.
The primary acid insoluble variables of Cluster VI are
1
terrigenous sediments derived from the Antler orogenic
belt, a highland west of the Bird Spring depocenter (Rich,
6 6
1969). i
i j
: !
Time-Trend Analysis j
; f
I |
Time-trend curves for bryozoans, oolites, algae, j
and brachiopods (Pig. 14) illustrate that the abundance |
i !
of these variables fluctuates irregularly. Cluster |
analysis shows that these four variables are more closely
; |
I
related to each other than to any of the other variables. I
: |
Algae is the only one of the four variables found in the j
Monte Cristo Limestone. Bryozoans and oolites are relative
ly abundant in one and two samples, respectively, in the
Bird Spring Group (Pig. 14). Algae and brachiopods are
present in many biomicrite samples (Pig. 14) which repre- j
i
sent microfacies 1, 2, and 3. If bryozoans, oolites, j
algae, and brachiopods are allochthonous as suggested in |
the cluster analysis, then time-trend analysis suggests
they were introduced to the depositional site at irregular
i intervals.
Time-trend curves for intraclasts and sponge
jspicules (Pig. 14) are highly correlated at only one point
i
;and show irregular fluctuations in abundance. Intraclasts
appear in three samples and sponge spicules in seven.
Both variables are rare in the Bird Spring Group and ab
sent in the Monte Cristo Limestone (Pig. 14). Both
variables are most abundant in a mud-supported biomicrite
(microfacies 1) at 770 feet (235 m) above the base of the
67
measured section (Pig. 14). Time-trend curves for these
two variables suggest that their abundance fluctuates ir
regularly (Pig. 14).
Cluster analysis reveals that echinoids, crinoids, j
and ostracodes are moderately correlated. Examination of
the time-trend curves for these three variables also shows
they are moderately correlated and their abundance
fluctuates irregularly (Pig. 15). The three variables ap
pear in microfacies 1, la, 2, and 3. Crinoid fragments
appear in the Monte Cristo Limestone and the Bird Spring
Group and echinoids and ostracodes are present only in the j
Bird Spring Group. Echinoids were noted in six samples as j
evidenced by the prominent peaks in the raw data curve !
I
(Pig. 13). The six samples are biomicrites which do not !
I
i
occur at regular intervals. Crinoids are rare in the ;
Monte Cristo Limestone where they occur as columnals in a
I
micrite matrix. In the Bird Spring Group crinoids appear
as columnals in biomicrites and rare biosparites. The
smoothed crinoid time-trend curve displays four con- |
spicuous peaks and several lesser peaks all of which occur j
at irregular intervals (Pig. 15)- These four prominent j
j
peaks correlate moderately with peaks in the echinoid
time-trend curve (Pig. 15)* Ostracodes appear only as
fragments and often are found in association with echinoids j
j
and crinoids. The smoothed time-trend curve for ostra
codes shows two broad peaks in the lower part of the Bird
; 68 ;
i
i Spring Group and several lesser peaks in the upper part
(Pig. 15). Peaks in ostraeode abundance correlate ;
1
moderately with peaks in the abundance of echinoids and j
crinoids (Pig. 15)* Examination of time-trend curves |
indicates that the three variables were transported to the 1
J j
:depositional site at irregular intervals. A moderate cor- j
relation could indicate that echinoids, crinoids, and j
i
ostracodes are derived from the same or similar source 1
i
,areas.
Samples that contain abundant faecal pellets in a J
micrite matrix with little or no other grains are be- j
i
i
lieved to represent a tidal flat or lagoonal environment j
(LaPorte, 1 9 6 9). Inspection of the pellet time-trend j
curve (Pig. 15) shows that a tidal flat or lagoonal !
■ i
i
!
environment existed at irregular intervals during deposi- i
j
tion of the Bird Spring Group. Paecal pellets are absent
in the Monte Cristo Limestone but are found in biopel-
! i
micrites, pelmicrites, and pelsparites in the Bird Spring j
1 Group. Although faecal pellets occur in many samples, the j
smoothed time-trend curve exhibits only five prominent
peaks which appear at irregular intervals (Pig. 15). The
peak at 240 feet (73 m) represents a pelmicrite unit
containing abundant faecal pellets (35 percent) and rare
algal fragments in a micrite matrix. At 700 feet (214 m)
there is a broad peak that represents two mud-supported
biopelmicrite units separated by a weathered sandstone
; 69
junit. The biopelmicrites contain faecal pellets, echinoid
I
spines, and algal fragments (Pigs. 14 and 15)* The broad
peak at 850 feet (259 m) also represents two mud-supported
biopelmicrite units that contain only 10 percent faecal
pellets. These two biopelmicrite units are separated by
a weathered sandstone. The relative scarcity of faecal
pellets and the presence of relatively abundant echinoids
and crinoids (Pig. 15) suggest that these two units repre
sent a low energy subtidal environment into which the
faecal pellets were transported (LaPorte, 1 9 6 9). There is
a peak at 1,100 feet (336 m) that is caused by two
carbonate units, a biopelmicrite and a pellet biosparite,
separated by a weathered sandstone. The biopelmicrite
unit contains 15 percent faecal pellets and rare algal
fragments (Pigs. 14 and 15)* The pellet biosparite unit
contains only 8 percent pellets and 25 percent other bio
genic grains (Pigs. 14 and 15) in a matrix of micrite and
sparry calcite. The abundant biogenic grains and the
presence of sparry calcite suggest that this unit denotes
deposition in a low energy subtidal environment into which
the faecal pellets have been transported (LaPorte, 1969)-
A peak in faecal pellet abundance at 1,770 feet (5^-0 m) is
caused by a pelsparite unit with 60 percent pellets in a
matrix of micrite and sparry calcite. Abundant faecal
pellets suggest low energy deposition while a matrix of
micrite and sparry calcite implies moderate energy. This
unit represents deposition in a tidal channel where in
complete winnowing of micrite could occur. Small peaks in
the pellet curve (Fig. 15) represent biomicrite units that i
i
contain only a few faecal pellets which are probably j
allochthonous. Heath e_t al. (1967) state that scattered j
1 i
; j
faecal pellets appear in many units deposited below wave |
base in the Bird Spring Group in the Arrow Canyon Range. 1
Whether or not the faecal pellets at Mountain Springs are
allochthonous, the time-trend curve suggests that a tidal
flat or lagoonal environment existed at irregular inter
vals.
Interpretation of the detrital quartz time-trend j
i
curve (Fig. 15) implies that only two of the thin section j
I
samples from the Bird Spring carbonates contain an appre- i
ciable amount (more than 10 percent) of detrital quartz.
|
Detrital quartz is not present in the studied portion of
the Monte Cristo Limestone. Detrital quartz is present
in 26 samples, however, it is abundant (more than 10 per
cent) in only 4 samples which are expressed as peaks in
the time-trend curve (Fig. 15). The peak at 150 feet
(45.8 m) represents the basal transgressive sandstone unit
(microfacies Oa) of the Bird Spring Group (Fig. 15). The
prominent peak at 1,400 feet (427 m) denotes a relatively
resistant quartzose sandstone unit that also represents
microfacies Oa. Biogenic grains are absent in microfacies
Oa. The other two prominent peaks at 650 feet (198 m) and
i . . . . . . . . . . . . . . . . . . . . . " " * “ ' ~ ‘ 7 1
|850 feet (258 m) represent laminated quartz-rich micrite
I i
1 |
and biomicrite, respectively, that are assigned to micro- ;
facies la. The quartz-rich biomicrite at 850 feet (259 hi)
; 1
contains fragments of echinoids, crinoids, ostracodes, and j
faecal pellets (Fig. 15). These two units are the only j
l
carbonate units in the Bird Spring Group that contain |
appreciable amounts of detrital quartz. j
The relationship between the high energy units of !
! quartzose sandstones and high energy carbonate grains is j
not adequately expressed in the quantitative analysis. !
!
Only two of the 77 quartzose sandstone units observed in
the field are included in the quantitative analysis be- j
i
cause of sampling problems. These two units are repre- j
; j
sented in Figure 15 as peaks in the detrital quartz time- ;
I
j trend curve at 150 feet (45.7 m) and 1,400 feet (427 m)
above the base of the measured section. Bryozoans,
oolites, algae, intraclasts, echinoids, and crinoids are
believed to be formed in relatively high energy environ
ments. They are found in massive biomicrite units that
denote deposition under low energy. As the high energy
grains are absent in the quartzose sandstone units, their I
|
abundance (Figs. 14 and 15) decreases to zero rather than j
; increases as the high energy quartzose sandstone units are
approached. The transition from the low energy biomicrites
to the high energy quartzose sandstones is abrupt on the
time-trend curves (Figs. 14 and 15) because, in most cases,
72
the stratigraphic distance between thin section samples is
too large (40 feet, 12.2 m) to adequately express fluctua
tions in abundance within a single unit.
Insoluble residue includes very fine-grained detri
tal quartz and chert. The time-trend curve (Pig. 15)
displays several peaks, some of which correlate with
detrital quartz peaks and some of which do not. Peaks in
insoluble residue abundance at 150 feet (45.8 m), 650 feet
(198 m), 850 feet (259 m), and 1,400 feet (427 m) correlate i
with peaks in detrital quartz abundance (Pig. 15)* Other >
peaks in insoluble residue abundance do not correlate with !
detrital quartz and are caused by the presence of chert.
!
The prominent peak in insoluble residue abundance at 1,900
feet (580 m) is due to chert as detrital quartz Is absent
i
above 1,600 feet (488 m) (Pig. 15)* Most samples above |
1
1,600 feet (488 m) are micrites with very rare biogenic
grains (microfacies 0). In these samples the chert noted
in the insoluble residue analysis is altered micrite.
The sparry calcite time-trend curve displays four
peaks at irregular intervals (Pig. 15)* The lowermost j
i
peak at 400 feet (122 m) is a reflection of the sparry |
calcite in a grain-supported biosparite unit (microfacies
3) which contains bryozoans, oolites, algae, and brachi-
pods (Pigs. 14 and 15)* The peak at 1,120 feet (342 m) |
i
depicts part of a mud-supported biosparite (microfacies 2).
There is a grain-supported biopelsparite unit (microfacies
i 73 |
■ !
3) at 1,690 feet (517 in) which causes a peak in sparry
calcite abundance (Fig. 15)* This unit also contains algae^
echinoids, crinoids, ostracodes, and faecal pellets (Figs. j
14 and 15). The peak in sparry calcite abundance at 1,770
feet (540 m) is caused by a grain-supported pelsparite unit
|
(microfacies 3) which contains faecal pellets and micrite. 1
As a sparry calcite matrix usually indicates relatively
high energy (Folk, 1 9 6 2), the four units containing a ;
1 sparry calcite matrix suggest that relatively high energy !
conditions were present infrequently and irregularly dur
ing deposition of the Bird Spring Group. j
Micrite, the most abundant variable, is present in
all samples from both the Monte Cristo Limestone and the
Bird Spring Group. The micrite time-trend curve exhibits
j
many irregular fluctuations in abundance (Fig. 15). i
i
Micrite is very abundant (up to 98 percent) in the Monte
Cristo Limestone (Fig. 15) and is also abundant (more than
50 percent) in many samples in the Bird Spring Group and
rare (7 to 25 percent) in only four samples. A low in |
S
micrite abundance is seen at the base of the Bird Spring j
Group (Fig. 15) which is a quartzose sandstone unit. The |
|
low in micrite at this point correlates with peaks in the j
curves for detrital quartz and insoluble residue (Fig. 15).
Micrite is rare (7 percent) in a biosparite unit (micro- j
i
facies 3) at 400 feet (122 m) above the base of the j
1
section (Fig. 15). The small amount of micrite in this unitj
i Is trapped between grains and represents incomplete
winnowing (Folk, 1962). A biopelsparite unit (microfacies
3) at 1,690 feet (517 m) produces a low in micrite j
abundance as evidenced by the raw data curve in Figure 15- |
There is a fourth low in micrite abundance at 1,770 feet
(54-0 m) caused by a pelsparite unit which contains only 18
percent micrite (Fig. 15)- In the stratigraphic interval
from 400 feet (122 m) to 1,600 feet (488 m) micrite is the
predominant matrix variable. The abundance of micrite in
this interval fluctuates irregularly (Fig. 15) in response
to variation in the rate of supply of the allochthonous
1
biogenic variables. Above 1,800 feet (550 m) micrite is
uniformly abundant (Fig. 15) often constituting 98 percent j
of the sample. Micrite is very abundant in the Monte
i
Oristo Limestone and the upper part of the Bird Spring j
Group but varies in abundance in the lower and middle part
of the Bird Spring Group.
The abundance of any variable is a function of the
I
1
rate of supply and the rate of removal. The high abundance j
of micrite is interpreted to mean that for long periods the
jrate of supply was greater than the rate of removal. As
|
micrite accumulates under low energy conditions (Folk,
1962), low energy conditions must have prevailed during
I
deposition of most of the carbonate units of the Monte |
i
I
Cristo Limestone and the Bird Spring Group.
Examination of the cluster and time-trend analyses
75
reveals an apparent contradiction. Cluster analysis states
that a moderate positive correlation exists between sparry
calcite and micrite, but time-trend analysis shows the j
i
abundance of sparry calcite to be inversely related to the
abundance of micrite. An apparent contradiction such as
i
this could easily be explained if at least part of the
I sparry calcite is altered micrite. In this case micrite j
would appear with sparry calcite and would decrease in
abundance as it altered to sparry calcite. In an R-mode j
factor analysis of the Cincinnatian limestones, Osborne
(1 9 6 7) reports a moderate correlation between micrite and
t
sparry calcite. The micrite and sparry calcite in the
Cincinnatian limestones are unrelated because sparry cal
cite is considered to be a relatively late diagenetic j
i
product (Osborne, 1 9 6 7). However, the sparry calcite in
the Bird Spring Croup is considered primary as it displays
radial fringes around allochems (Folk, 1962). A sparry
i
calcite matrix that exhibits radial fringes around allo
chems usually indicates high energy and a micrite matrix
low energy (Folk, 1962). As they suggest different energy
levels the two variables are generally thought to be
mutually exclusive. As micrite is ubiquitous, whenever
sparry calcite is present it is in association with micrite.!
This association is the explanation for the moderate cor- i
relation expressed in the cluster analysis. Both sparry
calcite and micrite are matrix variables, and when one in
76
creases in abundance the other must necessarily decrease.
This is the reason that the time-trend analysis illustrates
an inverse relationship between the abundance of sparry
calcite and micrite.
BATHYMETRIC MODEL
After determining the mierofacies and the inter- j
|
relationships of the variables, a bathymetric model is |
!
needed to adequately depict the depositional environment
in terms of the microfacies and the variables. A bathy- !
metric model for the stratigraphic section at Mountain
Springs is presented in Figure 16. This model is based on j
a deductive bathymetric model by Irwin (1 9 6 5) and an
inductive bathymetric model by Heath et al. (1967).
Figure 16 illustrates the depositional environment of the
upper Monte Cristo Limestone and the Bird Spring Group.
Units of the Bird Spring Group observed in the field can
be subdivided into a carbonate facies and a terrigenous
facies. The Monte Cristo Limestone contains only carbonate
units. Most of the carbonate units are massive micrites
and biomicrites that represent deposition below wave base
1
although there are a few biosparites that were deposited
above wave base. Most of the terrigenous units are
laminated and cross-bedded and represent deposition above
wave base.
Carbonate Microfacies
The environment of deposition is divided Into micro- j
facies in ascending order up the depositional dip (Fig.
Figure 16. Bathymetric model
78
LOW ENERGY HIGH ENERGY LOW ENERGY
SEA LEVEL
....1
WAVE BASE
MICROFACIES 0 MICROFACIES I MICROFACIES 2 MICROFACIES 3
MICROFACIES la MICROFACIES Oa
PELLETS
ECHINOIDS
CRINOIDS
SPARRY CALCITE MATRIX
MICRITE MATRIX
VO
FIG. 16. - BATHYMETRIC MODEL (AFTER HEATH £T A]*., 1967; IRWIN, 1965)
i16). Microfacies 0 (Pig. 16) is an almost pure micrite
I that contains rare biogenic grains and depicts deposition
in quiet water below base level. Microfacies 1 (Pig. 16) |
is a biomicrite containing abundant biogenic grains. It j
denotes deposition still below base level but closer to |
the source of the biogenic grains. Microfacies 2 (Pig. |
16) includes mud-supported biomicrites and grain-supported j
biosparites that were deposited below and above base
level, respectively. Biogenic grains are generally more
abundant than in microfacies 1. Microfacies 3 (Pig. 16) j
contains grain-supported biosparites and mud-supported
biomicrites both with abundant biogenic grains. The bio
sparites contain rare micrite and denote deposition above
I
;wave base under moderate energy. The biomicrites contain
faecal pellets that represent deposition under low energy
! !
shoreward of the zone of maximum turbulence.
Quartz-rich Microfacies
Quartz-rich units at Mountain Springs are best sub-
f
divided into two microfacies. Microfacies Oa (Pig. 16) is
a laminated and cross-bedded quartzose sandstone that
|portrays deposition above base level but does not contain
biogenic grains. Microfacies la (Pig. 16) is a quartz-
rich biomicrite that is similar to microfacies 1 but con-
!
tains detrital quartz grains and which represents deposi
tion below base level. There are no quartz-rich equivalents!
to microfacies 2 and 3.
Succession of Microfacies
I Stratigraphic units at Mountain Springs succeed each
other in both a cyclic and a non-cyclic manner. The upper
| Monte Cristo Limestone represents non-cyclic deposition of
microfacies 0. The Bird Spring Group may be conveniently j
divided at approximately 1,600 feet (488 m) above the base j
i
of the measured section. Below this point it consists of j
alternating sandstones, which are placed in microfacies j
|Oa, and carbonates which represent the gamut of carbonate J
microfacies described in this paper. Above 1,600 feet |
(488 m) the Bird Spring Group is composed primarily of
| microfacies 0 and 1 but also includes two units of micro-
! facies 3. Units in the upper Bird Spring Group do not
appear in a systematic manner.
Rocks of the Monte Cristo Limestone and the Bird
Spring Group analyzed for this report were deposited in the
Cordilleran miogeosyncline (Heath ejb al., 1967) under stable
and unstable conditions. The upper Monte Cristo Limestone
is a massive, relatively homogenous micrite that was
probably deposited in a stable environment (Krumbein and
Sloss, 1951)* Alternating sandstones and carbonates in
the lower Bird Spring Group reflect changes in energy
level. The laminated sandstones suggest high energy and
most of the carbonates imply low energy. Fluctuations in
82
energy level and cyclic sedimentation denote an unstable
environment (Krumbein and Sloss, 1951)* Cyclic sedimenta
tion as seen in the lower Bird Spring Group implies
alternating transgression and regression owing either to
eustatic changes in sea level or tectonic activity of the
shelf,
Bissell (1964) believes that fluctuations in sea
level are related to orogenic and epeirogenic activity near
or within the depositional basin. Dott (1964) states
that rhythmic sedimentary patterns in geosynclines are the
result of a combination of glacio-eustatic changes and
diastrophic changes in sea level. He cites the incidence
of erosional unconformities and coarse clastic wedges in
the Pennsylvanian of east-central Nevada as evidence of
diastrophism. Although there are no unconformities or
coarse clastic wedges exposed at Mountain Springs, it is
impossible to state with confidence whether the cyclic
sedimentation is caused by glacio-eustatic or diastrophic
changes in sea level.
Rocks of the upper Bird Spring Group are pre
dominantly massive to thick-bedded micrite and contain no
detrital quartz. The lack of cyclic sedimentation and the
absence of detrital quartz signify a change from unstable
to stable conditions (Krumbein and Sloss, 1951)*
COMPARISON WITH OTHER AREAS
i
t
A brief comparison is offered among the Bird Spring |
Group at Mountain Springs and a Pennsylvanian limestone
in the mid-continent and two other exposures of the Bird
!
Spring Group in southern Nevada. As interpretation of the
depositional environment of the Bird Spring Group is the
major objective of this study, no comparison of the upper
Monte Cristo Limestone is made. In a quantitative petro-
graphic study of the Leavenworth Limestone (Pennsylvanian-
i
Yirgilian) of Kansas, Toomey (1966) reports that two of j
32 localities analyzed represent a mudstone facies that j
l
contains 85 percent micrite, 3-6 percent coated-grains, |
j
3.4 percent sparry calcite and 0.9 percent pellets.
Toomey's (1966) mudstone facies is similar to microfacies j
I
1 described from the Bird Spring Group at Mountain
Springs. Toomey (1966) interpreted his mudstone facies
as a local development in which a lack of skeletal debris j
is the most prominent feature. As described in this j
|
report, microfacies 1 is probably more than merely a local i
!
development because of its abundance in the stratigraphic
column.
No direct stratigraphic correlation will be at
tempted with the Bird Spring Group because of a lack of j
recognizable, laterally continuous marker beds. At Lee
Canyon Rich (1963) reported that the lower Bird Spring
Group is composed of reddish-brown cross-bedded elastics
and spar-cemented carbonates overlain by irregular alterna
tions of biocalcarenitic and skeletal calcarenitic lime
stones all of which imply a transgression followed by
deposition under unstable shelf conditions. The middle
!Bird Spring Group at Lee Canyon indicates warm, shallow-
water deposition of coral and algal rich carbonates that
denote stable conditions (Rich, 1963). The change from
unstable to stable may correspond to a similar change
observed in the Bird Spring Group at Mountain Springs.
The upper Bird Spring Group at Lee Canyon includes cal
carenitic and biocalcarenitic limestone alternating with
fine-grained limestone and calcareous shale (Rich, 1 9 6 3).
This portion of the section records a change to unstable
conditions (Rich, 1963)* The stratigraphic section ex
posed at Mountain Springs does not exhibit a later change
to unstable deposition.
.Although the carbonate microfacies at the Arrow
Canyon Range are similar to those at Mountain Springs,
i there is little gross similarity between the Bird Spring
Group exposed at Mountain Springs and at the Arrow Canyon
Range. At the Arrow Canyon Range, Heath et al. (1 9 6 7)
noted that the Bird Spring Group is a cyclic, miogeo-
synclinal sequence that contains 78 complete cycles. The
lower part of the section is composed of 46 cycles that
r - ”.......” " — ..........~ 85"
represent a gradual transgression, whereas the upper part
of this 46 cycle sequence includes a massive influx of
detrital quartz (Heath at al•, 1967). These 46 cycles
encompass the whole gamut of microfacies hut do not include
units composed entirely of detrital quartz. Alternating
|units in the lower Bird Spring Group at Mountain Springs
are composed entirely of detrital quartz. At the Arrow j
Canyon Range the upper Bird Spring Group exhibits 32
cycles that signify a gradual regression (Heath et al.,
1967). There are no cyclic deposits in the upper Bird
Spring Group at Mountain Springs.
i SUMMARY AID CONCLUSIONS
A detailed quantitative study of a stratigraphic
section 2,260 feet (688 m) thick including the upper Monte
Cristo Limestone and the Bird Spring Group outlines
-epeiric sedimentation under stable and unstable condi-
l
’tions. Rocks of the upper Monte Cristo Limestone and the
[Bird Spring Group exposed at Mountain Springs are sub
divided into six microfacies utilizing the classification
of Heath et_ al. (1967).
Cluster analysis groups the variables into seven
clusters: five composed of various organic and inorganic
!grains and alteration products, one composed of terri-
!genous or acid insoluble variables, and one of carbonate
!
matrix variables. The various grains are rare and appear
!
as scattered fragments in a micrite matrix. High energy
grains as bryozoans, oolites, algae, echinoids, and
crinoids in a micrite matrix are probably allochthonous.
Grain abundance varies irregularly with time. Acid in-
|soluble variables are abundant in the lower Bird Spring
j
|Group which contains many units of detrital quartz. Sparry
icalcite and micrite are rare and abundant, respectively.
| The distribution of the variables with time sug
gests that the rocks at Mountain Springs were deposited in
the Cordilleran miogeosyncline under stable and unstable
conditions. The upper Monte Cristo Limestone was deposited
Junder stable conditions that produced massive, low energy
i
jmicrites with very rare biogenic grains. After an interval
of erosion the alternating sandstones and biomicrites of
the lower Bird Spring Group were deposited. Fluctuations
in energy level and/or the rate of supply of terrigenous
!quartz occurred in an unstable environment. Instability
later gave way to stability and energy level fluctuations
diminished, resulting in deposition of an almost unbroken
!sequence of micrites and biomicrites.
REFERENCES
8 8
REFERENCES
Agnew, A. F., 1957, Ostracodes of the Paleozoic: In
Treatise on marine ecology and paleoecology, v. 2
paleoecology: Geol. Soc. America Mem. 67, P* 931-
936.
Bissell, H. J., 1964, Patterns of sedimentation in Pen
nsylvanian and Permian strata of part of the eastern
Great Basin: in Symposium on cyclic sedimentation,
Merriam, D. P., ed., Kansas Geol. Survey Bull. 169,
v. I, p. 43-56.
Chayes, Felix, 1956, Petrographic modal analysis— an
elementary statistical appraisal: New York, John
Wiley & Sons, Inc.
Cooper, G. A., 1957, Echinoids of the Paleozoic: in
Treatise on marine ecology and paleoecology, v. 2
paleoecology: Geol. Soc. America Mem. 6 7, p. 979-
980.
Dott, R. H., 1958, Cyclic patterns in mechanically
deposited Pennsylvanian limestones of northeastern
Nevada: Jour. Sedimentary Petrology, v. 28, p. 3-14.
_______, 1964, Superimposed rhythmic stratigraphic pat
terns in motile belts: in Symposium on cyclic sedi
mentation, Merriam, D. F., ed., Kansas Geol. Survey
Bull. 169, v. I, p. 69-85.
Duncan, Helen, 1957, Bryozoans: in Treatise on marine
ecology and paleoecology, v. 2 paleoecology: Geol.
Soc. America Mem. 6 7, p. 783-800.
Fisher, R. A. and Yates, Frank, 1963, Statistical tables
for biological, agricultural, and medical research:
New York, Hafner Publishing Co., Inc., 147 p.
Folk, R. L., 1962, Spectral subdivision of limestone
types, in Classification of carbonate rocks: Am.
Assoc. Petroleum Geologists Mem. 1, p. 62-84.
89
Geological Society of America, 1963, Rock color chart:
reprinted from National Research Council Chart, 1948,
Harhaugh, J. V/. and Merriam, D. P., 1968, Computer ap
plications in stratigraphic analysis: New York,
John Wiley & Sons, Inc., 282 p.
Heath, C. P. M., 1965, Microfacies of the Lower Bird
Spring Group (Pennsylvanian-Permian), Arrow Canyon
Range: Unpubl. Ph.D. Dissertation, Dept, of Geology,
Univ. 111., Urbana, 156 p.
Heath, C. P. M., Lumsden, D. N., and Carozzi, A. V., 1967
Petrography of a carbonate transgressive-regressive
sequence: the Bird Spring Group (Pennsylvanian),
Arrow Canyon Range, Clark County, Nevada: Jour.
Sedimentary Petrology, v. 37, p. 377-4-00.
Hewett, D. P., 1931, Geology and ore deposits of the
Goodsprings Quadrangle, Nevada: U. S. Geological
Survey, Prof. Paper 162, 102 p.
_______, 1956, Geology and mineral resources of the
Ivanpah Quadrangle, California and Nevada: U. S.
Geological Survey Prof. Paper 275, 172 p.
Hoskin, C. M., 1963, Recent carbonate sedimentation on
Alacran Reef, Yucatan, Mexico: in Natl. Acad, of
Sci.-Natl. Res. Coun., Publ. 1089, Off. of Naval Res.
Report No. 19, 160 p.
Hjulstrom, P., 1939, Transportation of detritus by moving
water, in Trask, P. D. (ed.), Recent marine sedi
ments: Tulsa, Oklahoma, Am. Assoc. Petroleum
Geologists, p. 5-31.
Irwin, M. L., 1965, General theory of epeiric clear water
sedimentation: Am. Assoc. Petroleum Geologists
Bull., v. 49, p. 445-459.
Krumbein, W. C. and Sloss, L. L., 1951, Stratigraphy and
sedimentation: San Francisco, W. H. Freeman and Co.,
497 p.
Langenheim, R. L., Carss, B. W., Kennerly, J. B.,
McCutcheon, Y. A., and Waines, R. H., 1962, Paleozoic
section in Arrow Canyon Range, Clark County, Nevada,
Am. Assoc. Petroleum Geologists Bull., v. 46, p.
592-609.
91
LaPorte, L. P., 1969, Recognition of a transgressive
carbonate sequence within an epeiric sea: Helderberg
Group (Lower Devonian) of New York State: in
Depositional environments in carbonate rocks,
Friedman, G. M., ed., Soc. Econ. Paleontologists and
Mineralogists, Spec. Publ. No. 14, p. 98-119.
Laudon, L. R., 1957, Crinoids: in Treatise on marine
ecology and paleoecology, v. 2 paleoecology: Geol.
Soc. America Mem. 67, p. 961-972.
Longwell, C. R. and Dunbar, C. 0., 1936, Problems of
Pennsylvanian-Permian boundary in southern Nevada:
Am. Assoc. Petroleum Geologists Bull., v. 20, no. 9,
p. 1198-1207.
Lumsden, D. N., 1965, Microfacies of the Middle Bird
Spring Group (Pennsylvanian-Permian), Arrow Canyon
Range, Clark County, Nevada: Unpubl. Ph.D. Disserta
tion, Dept, of Geology, Univ. 111., Urbana, 104 p.
Newell, N. D. and Rigby, J. R., 1957, Geological studies
on the Great Bahama Bank: in Regional aspects of
carbonate deposition, Leblanc, R. J. and Breeding,
J. G., eds. Soc. Econ. Paleontologists and Mineral
ogists, Spec. Publ. No. 5, p. 15-72.
Osborne, R. H., 1967, The American Upper Ordovician
Standard. VIII. R-mode factor analysis of
Cincinnatian limestones: Jour. Sedimentary
Petrology, v. 37, p. 649-657.
Plas, L., van der, and Tobi, A. C., 1965, A Chart for
judging the reliability of point counting results:
Am. Jour. Sci., v. 263, p. 87-90.
Reade, H. L., Jr., 1962, Stratigraphy and paleontology of
the Monte Cristo Limestone, Goodsprings Quadrangle,
Nevada: Unpubl. Master's Thesis, Dept, of Geological
Sciences, Univ. Southern Calif., Los Angeles, 125 p.
Rich, Mark, 1961, Stratigraphic section and fusulinids of
the Bird Spring Formation near Lee Canyon, Clark
County, Nevada: Jour. Paleontology, v. 35, p. 1159-
1180.
92
Rich, Mark, 1 9 6 3, Petrographic analysis of the Bird
Spring Group (Oarboniferous-Permian) near Lee Canyon,
Clark County, Nevada: Am. Assoc. Petroleum
Geologists Bull., v. 47, p* 1657-1681.
1
;_______, 1964, Petrographic classification and method of
| description of carbonate rocks of the Bird Spring
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Petrology, v. 34, p. 365-378.
_______, 1969, Petrographic analysis of Atokan carbonate
i rocks in central and southern Great Basin: Am. Assoc.
Petroleum Geologists Bull., v. 53, p. 340-366.
Sokal, R. R. and Sneath, P. H. A., 1963, Principles of
numerical taxonomy: San Francisco, W. H. Freeman and
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Toomey, D. F., 1966, Application of factor analysis to a
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Geol. Survey Sp. Dist. Publ. 27, 29 P*
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and their application for correlation of sedimentary
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APPENDICES
APPENDIX A
DESCRIPTION OP STRATIGRAPHIC COLUMN
9 4
~ ~ 95 !
APPENDIX A
DESCRIPTION OP STRATIGRAPHIC SECTION
Unit
No.
182
181
180
179
178
Description and Sample
Thickness No.
Pennsylvanian
Bird Spring Group
Calcilutite, medium-gray, 48
N5, weathers very light- 47
gray, N8, thick-bedded,
contains minor amounts
of silty quartz; poorly
exposed.
Thickness 110 feet
46
45
44
43
42
41
Calcilutite, medium-gray,
N5, weathers light-gray,
N7, massive to thick-
bedded; contains
fusulinids and minor
amounts of chert.
Thickness 205 feet
Covered interval.
Thickness 20 feet
Calcilutite, medium-gray,
N5, weathers light-gray,
N7, medium-bedded, poorly
exposed; contains scatter
ed chert nodules.
Thickness 90 feet
Calcilutite, medium-dark- 38
gray, N4, weathers light-
gray, N7, thick-bedded,
contains abundant chert
nodules.
Stratigraphic
Distance
Above Base
(Feet)
2,330
2,290
2,250
2,210
2,170
2,130
2,090
2,050
1,930
Thickness 8 feet
96 |
Unit
No.
177
176
175
174
175
Description and Sample
Thickness______________ No.
Calcilutite, medium-light-
gray, N6, weathers very
light-gray, N8, thick-
bedded; contains minor
amounts of chert and cal-
cite veins.
Thickness 27 feet
Calcilutite, medium-gray, 37
N5, weathers light-gray, 36
N7, thick-bedded; contains 35
minor amounts of echinoids
and crinoids near the base
of the unit.
Thickness 115 feet
Calcilutite, medium-gray, 34
N5, weathers light-gray,
N7, thick-bedded, non-
resistant; partly re
crystallized to sparry
calcite.
Thickness 20 feet
Calcilutite, medium-dark- 33
gray, N4, weathers very
light-gray, N8, thick-
bedded; displays a step
like appearance in out
crop.
Thickness 57 feet
Calcilutite, medium-dark- 32
gray, N4, weathers light-
gray, N7, non-resistant;
contains echinoids,
crinoids, and sparry
calcite.
Thickness 28 feet
Stratigraphic
Distance
Above Base
(Feet)
1,885
1,850
1,810
1,770
1,730
1,690
Unit Description and Sample
No. Thickness No.
172 Calcilutite, medium- 31
light-gray, N6, weathers
light-gray, N7, massive
to thick-bedded; con
tains small corals.
Thickness 32 feet
171 Calcilutite, medium-
light-gray, N6, weathers
very light-gray, N8, thick-
bedded; contains a few
corals and chert nodules.
Thickness 12 feet
170 Calcilutite, very light- 30
gray, N8, thick-bedded;
contains a 1 foot bed of
chert 10 feet above the
base of the unit.
Thickness 31 feet
169 Calcilutite, medium-light-
gray, N6, weathers light-
gray, N7, massive resistant.
Thickness 11 feet
168 Sandstone, quartzose,
light-gray, N7, weathers
grayish-orange-pink, 5YR7/2,
very fine-grained, laminated,
relatively non-resistant.
Diastem.
Thickness 8 feet
167 Calcilutite, dark-gray, N3, 29
weathers medium-dark-gray,
N4, massive to thick-
bedded .
Stratigraphic I
Distance j
Above Base
(Feet) |
1,650 |
1,610
1,570
Thickness 21 feet
Unit
No.
166
i
| 165
164
163
: 162
161
Description and
Thickness
Sandstone, weathered,
upper and lower contacts
obscured.
Thickness 12 feet
Calcilutite, dark-gray,
N3, weathers medium-dark
gray, N4, massive.
Thickness 11 feet
Calcilutite, medium-light- 28
gray, N6, weathers light-
gray, N7, massive to thick-
bedded .
Thickness 17 feet
Sandstone, quartzose, light-
gray, N7, weathers grayish-
orange-pink, 5YR7/2, very
fine-grained, laminated and
cross-bedded, relatively
non-resistant. Diastem.
Thickness 23 feet
Calcilutite, medium-gray, 27
N5> weathers medium-light-
gray, N6, massive to thick-
bedded, contains corals
(Caninophyllum sp.) and
fusulinids (Fusulinella sp.).
Specimens of Caninoph.yllum
sp. are found in a recumbent
position and are severely
compressed•
Thickness 47 feet
Sandstone, weathered.
Thickness 24 feet
Sample
No.
Stratigraphic j
Distance
Above Base
(Feet) I
1,530
1,490
Unit
go.
I 160
' 159
158
[ 157
I 156
| 155
i
! 154
99 !
Stratigraphic j
Description and Sample Distance
Thickness No. Above Base !
---------- — ------- (TeeT)-!
i
Calcilutite, medium-gray, !
N5, weathers medium-light- I
gray, N6, medium-bedded; j
contains veins of j
secondary calcite. j
Thickness 15 feet j
Sandstone, quartzose, 26 1*370 I
light olive-gray, 5Y6/1,
weathers grayish-orange-
pink, 5YR7/2, very fine
grained, laminated and
cross-bedded, relatively
non-resistant. Diastem. j
Thickness 48 feet
I
Calcilutite, medium-gray, |
N5» weathers medium- j
light-gray, N6, massive. j
Thickness 12 feet
i
Sandstone, weathered.
Thickness 14 feet
Calcilutite, medium-gray,
N5t weathers medium-light-
gray, N6, thick-bedded,
contains fusulinids and
small chert nodules.
Thickness 5 feet
Sandstone, weathered.
Thickness 14 feet
Calcilutite, medium-gray,
N5» weathers medium-light-
gray, N6, massive, contains j
chert nodules. |
Thickness 2 feet
Unit
No.
153
152
151
150
149
148
147
100 !
j
Stratigraphic j
Description and Sample Distance
Thickness______________ No. Above Base
(Feet)
Sandstone, weathered.
Thickness 15 feet
Calcilutite, medium-
gray, N5, weathers
medium-light-gray, N6,
massive to thick-bedded,
contains chert nodules,
stylolites, and corals
(Chaetetes sp.).
Thickness 91 feet
Sandstone, weathered.
Thickness 38 feet
Calcilutite, light-gray, 23 1,175
N7, weathers very light-
gray, N8, massive.
Thickness 5 feet
Sandstone, quartzose,
grayish-orange-pink,
5YR7/2, very fine-grained,
laminated, non-resistant.
Diastem.
Thickness 21 feet
Calcilutite, medium-gray,
N5. weathers medium-light-
gray, N6, massive, contains
a bed of chert nodules near
the top of the unit.
Thickness 4 feet
Sandstone, weathered.
25
24
1,290
1,255
Thickness 6 feet
101
Unit
No.
146
145
144
143
142
141
Stratigraphie
Description and Sample Distance
Thickness______________ No. Above Base
(Feet)
Calcilutite, medium-
gray. N5» weathers medium-
light-gray, N6, massive
to thick-bedded, contains
coral and brachiopod
fragments.
Thickness 4 feet
Sandstone, weathered.
Thickness 5 feet
Calcilutite, medium-dark-
gray, N4, weathers medium-
gray, N5> thick-bedded,
contains calcite veins.
Thickness 4 feet
Sandstone, weathered.
Thickness 7 feet
Calcilutite, medium-dark- 22 1,120
gray, N4, weathers medium-
gray, N5> massive; con
tains sparry calcite,
echinoids, and crinoids.
Thickness 3-5 feet
Sandstone, quartzose,
grayish-orange-pink,
5YR7/2, very fine-grained,
laminated, non-resistant;
contains calcium carbonate
matrix. Diastem.
Thickness 15*5 feet
! Unit
i No .
140
i
j 139
138
i
i
I
i 1 3 7
136
i
J
135
134
I
133
Description and Sample
Thickness No.
Calcilutite, medium-
dark-gray, N4, weathers
medium-gray, N5»
massive.
Thickness 4 feet
Sandstone, weathered.
Thickness 12 feet
Calcilutite, medium- 21
dark-gray, N4, weathers
medium-gray, N5» massive,
contains echinoids and
faecal pellets.
Thickness 2 feet
Sandstone, weathered.
Thickness 6 feet
Calcilutite, medium-
dark-gray, N4, weathers
medium-gray, N5, massive
to thick-bedded.
Thickness 2.5 feet
Sandstone, weathered.
Thickness 18.5 feet
Calcilutite, medium- 20
dark-gray, N4, weathers
medium-gray, N5» massive;
contains brachiopods and
calcite veins.
Thickness 5 feet
Sandstone, weathered.
Thickness 20 feet
102 '
i
I
Stratigraphic
Distance j
Above Base j
(Feet) j
1,085
1,055
! Unit
I No,
i 132
i
j
j 131
130
l
i
129
128
i
i
i 127
i
126
j
i
: 125
Description and Sample
Thickness No.
Calcilutite, medium-
dark-gray, N4, weathers
medium-gray, N5, thick-
bedded, contains chert
nodules.
Thickness 6 feet
Sandstone, weathered.
Thickness 14 feet
Calcilutite, medium- 19
dark-gray, N4, weathers
medium-gray, N5» massive;
contains brachiopods,
echinoids, crinoids, and
faecal pellets.
Thickness 6 feet
Sandstone, weathered.
Thickness 6.5 feet
Calcilutite, medium-
dark-gray, N4, weathers
medium-gray, N5> massive;
contains brachiopods and
corals.
Thickness 2 feet
Sandstone, weathered.
Thickness 6.5 feet
Calcilutite, medium-dark-
gray, N4, weathers medium-
gray, N5» massive.
Thickness 2 feet
Sandstone, weathered.
Thickness 18 feet
103 !
Stratigraphic!
Distance |
Above Base j
(Feet) I
1,010
104
■ Unit
| No.
I
: 124
j
| 123
122
121
i
[
i
|
I 120
119
i
j 1 1 8
Stratigraphic
Description and Sample Distance
Thickness______ No. Ahove Base
(Feet)
Chert, dusky blue
5PB3/2.
Thickness 1 foot
Calcilutite, medium-
dark-gray, N4, weathers
medium-gray, N5»
massive resistant.
Thickness 3 feet
Sandstone, quartzose,
moderate-orange-pink,
5YR8/4, non-resistant.
Thickness 16 feet
Calcilutite, medium-dark-
gray, N4, weathers medium-
gray, N5, massive; con
tains crinoid and coral
fragments.
Thickness 2 feet
Sandstone, weathered.
Thickness 6 feet
Calcilutite, medium-
gray, N5, weathers medium-
light-gray, N6, medium-
bedded; contains coral
fragments and chert
nodules.
Thickness 6 feet
Sandstone, quartzose,
moderate-orange-pink,
5YR8/4, very fine
grained, laminated,
poorly exposed. Diastem.
Thickness 15 feet
Unit
No.
| 117
i
j
i
116
115
114
113
| 112
i
i
i
1 1 1
Description and Sample
Thickness No.
Calcilutite, medium-
gray, N5> weathers medium-
light-gray, N6, non-
resistant, contains fine-
quartzose-sands, crinoids,
and chert nodules.
Thickness 21 feet
Calcilutite, medium-dark-
gray, N4, weathers medium-
gray, N5> massive; contains
Chaetetes sp. partially re-
placed by chert.
Thickness 3 feet
Calcilutite, medium-dark-
gray, N4, weathers medium-
light-gray, N6, non-
resistant; contains laminae
of very fine-quartzose sand.
Diastem.
Thickness 12.5 feet
Chert, dusky-blue 5PB3/2.
Thickness 1.5 feet
Sandstone, weathered.
Thickness 12 feet
Calcilutite, medium-gray,
N5* weathers medium-light-
gray, N6, thick-bedded,
contains chert in the upper
part of the unit.
Thickness 5 feet
Sandstone, weathered.
Thickness 6 feet
105
Stratigraphic
Distance
Above Base
(Feet) j
Unit
lo.
110
109
108
107
106
105
104
103
106 I
I
Stratigraphic j
Description and Sample Distance
Thickness______________ No, Above Base
(Feet)
|
Calcilutite, medium- I
gray, N5» weathers light- !
gray, N7, massive; con- j
tains calcite veins and
chert nodules.
Thickness 5 feet
Sandstone, weathered.
Thickness 4 feet
Calcilutite, medium-gray, 18 850
N5> weathers medium-
light-gray, N6, contains
laminae of very fine-
quartzose sand.
Thickness 4 feet
Sandstone, weathered.
Thickness 11 feet
Calcilutite, medium-gray,
N5, weathers medium-light-
gray, N6, massive; contains
corals and calcite veins.
Thickness 6 feet
Sandstone, weathered.
Thickness 10 feet
Calcilutite, medium-dark-
gray, N4, weathers medium-
light-gray, N5f massive.
Thickness 5 feet
Sandstone, weathered;
contains fragments of
calcareous tufa.
Thickness 10 feet
Unit
No,
102
101
100
99
98
97
96
107!
Stratigraphic!
Sample Distance j
No* Above Base
(Feet) |
Calcilutite, medium-dark- 17 805 i
gray, N4, weathers medium- |
light-gray, N6, thick-
bedded; contains a chert
bed 0.5 feet thick near
the top of the unit.
Thickness 5 feet
Sandstone, weathered.
Thickness 20 feet
Calcilutite, medium-dark-
gray, N4, weathers light-
gray, N7* massive.
Thickness 4 feet
Calcilutite, medium-dark-
gray, N4, weathers very i
light-gray, N8, non- j
resistant; contains
echinoids and crinoids.
Thickness 27 feet
Calcilutite, medium-gray, 16 770
N5> weathers medium-
light-gray, N6, massive;
contains veins of
secondary calcite.
Thickness 4 feet
Sandstone, weathered.
Thickness 5 feet
Calcilutite, medium-gray,
N5> weathers medium-
light-gray, N6, massive.
Description and
Thickness
Thickness 5 feet
1 0 8
Unit
No.
95
94
93
92
91
90
89
88
Stratigraphic
Sample Distance
No. Above Base
(Feet)
Sandstone, weathered.
Thickness 5 feet
Calcilutite, medium-dark- 15 730
gray, N4, weathers medium-
gray, N5, thick-bedded;
contains faecal pellets
and echinoid fragments.
Thickness 5 feet
Sandstone, weathered;
contains fragments of
calcareous tufa.
Thickness 9 feet
Calcilutite, medium-dark-
gray, N4, weathers medium-
gray, N5» massive to thick-
bedded •
Thickness 9 feet
Sandstone, weathered.
Thickness 2 feet
Calcilutite, medium-dark-
gray, N4, weathers medium-
gray, N5» massive; contains
calcite veins.
Thickness 4 feet
Sandstone, weathered.
Thickness 5 feet
Calcilutite, medium-dark-
gray, N4, weathers medium-
gray, N5, massive.
Thickness 4 feet
Description and
Thickness
Unit
No.
87
86
85
84
83
82
81
8 0
Description and Sample
Thickness No*
Sandstone, weathered.
Thickness 2 feet
Calcilutite, medium-gray, 14
N5» weathers medium-
light-gray, N6, massive;
contains faecal pellets.
Thickness 11 feet
Sandstone, weathered.
Thickness 15 feet
Chert.
Thickness 1 foot
Sandstone, weathered;
contains fragments of
calcareous tufa.
Thickness 12 feet
Calcilutite, medium-dark- 13
gray, N4, weathers light-
gray, N7* contains laminae
of very fine quartzose
sand.
Thickness 4 feet
Sandstone, weathered.
Thickness 8 feet
Calcilutite, medium-dark-
gray, N4, weathers medium-
light-gray, N6, massive;
contains chert nodules.
Thickness 4 feet
109 '
Stratigraphic
Distance
Above Base ;
(Feet) i
690
650
1 1 0
Unit
Ho,
79
78
77
76
75
74
73
Description and
Thickness
Sandstone, weathered;
contains fragments of
calcareous tufa.
Thickness 33 feet
Stratigraphic
Sample Distance
No. Above Base
(Feet)
Calcilutite, medium-dark-
gray, N4, weathers medium
gray, N5> massive to
thick-bedded; contains
calcite veins.
Thickness 8 feet
Sandstone, weathered.
Thickness 4 feet
Calcilutite, medium-gray,
N5* weathers medium-
light-gray, N5j thick-
bedded; contains calcite
veins.
Thickness 16 feet
Sandstone, weathered;
contains fragments of
calcareous tufa.
Thickness 20 feet
Calcilutite, medium-
light-gray, N6, weathers
light-gray, N7, massive.
Thickness 9 feet
Sandstone, weathered.
Thickness 15 feet
Unit Description and Sample
Ho, Thickness_______ Ho,
72 Calcilutite, medium- 12
light-gray, N6,
weathers light-gray,
H7, massive; contains
chert nodules.
Thickness 13 feet
71 Sandstone, weathered;
contains fragments of
calcareous tufa.
Thickness 10 feet
70 Calcilutite, medium-
light-gray, H6, weathers
light-gray, H7» massive.
Thickness 2 feet
69 Sandstone, weathered.
Thickness 5 feet
68 Calcilutite, medium-
light-gray, H6,
weathers light-gray,
H7> massive; contains
chert nodules.
Thickness 9 feet
67 Sandstone, weathered.
Thickness 25 feet
66 Calcilutite, medium-
light-gray, H6,
weathers light-gray,
N7, massive.
Thickness 3 feet
65 Sandstone, weathered.
Thickness 11 feet
Stratigraphic
Distance
Above Base
530
Unit Description and Sample
No. Thickness ____ No.
64 Calcilutite, medium- 11
light-gray, N6,
weathers light-gray,
N79 thick-bedded.
Thickness 24 feet
63 Sandstone, weathered.
Thickness 18 feet
62 Calcilutite, medium- 10
light-gray, N6,
weathers light-gray,
N7, massive to thick-
bedded; contains
brachiopods.
Thickness 23 feet
61 Sandstone, weathered.
Thickness 28 feet
60 Calcilutite, medium-
light-gray, N6,
weathers light-gray,
N7> massive; contains
calcite veins.
59 Sandstone, weathered.
Thickness 1 foot
58 Calcilutite, medium-
light-gray, N6,
weathers light-gray,
N7, massive.
Thickness 1 foot
57 Sandstone, weathered.
Thickness 2 feet
1 1 2
Stratigraphic
Distance
Above Base
(Feet)
450
410
113
Unit
No.
56
55
54
53
52
51
50
49
Stratigraphic
Description and Sample Distance
Thickness No. Above Base
(Feet)
Calcilutite, medium-gray,
N5* weathers medium-
light-gray, N6, thick-
bedded; contains
brachiopods.
Thickness 3 feet
Sandstone, weathered.
Thickness 1 foot.
Calcilutite, medium-gray,
N6, thick-bedded; contains
brachiopod fragments.
Thickness 2 feet
Sandstone, weathered.
Thickness 1 foot
Calcilutite, medium-gray,
N5* weathers light-gray,
N7* massive; contains
calcite veins.
Thickness 2 feet
Sandstone, weathered.
Thickness 1 foot
Calcilutite, medium-dark-
gray, N4, weathers medium-
gray, N5t massive.
Thickness 1 foot
Sandstone, weathered.
Thickness 1 foot
Unit
No *
| 48
i
I
i
47
46
i
45
j
| 44
|
i
43
! 42
j
f
| 41
114 |
Stratigraphic
Distance j
Above Base
(Feet)
Calcilutite, medium-
gray, N5> weathers medium-
light-gray, N6, massive. j
Thickness 2 feet |
Sandstone, weathered. j
Thickness 1 foot i
Calcilutite, medium-gray,
N5f weathers medium-light-
gray, N6, thick-bedded;
contains brachiopods and
corals.
Thickness 2 feet
Sandstone, weathered.
Thickness 1 foot
Calcilutite, medium-gray,
N5* weathers medium-light-
gray, N6, massive; contains
crinoid columnals.
Thickness 2 feet
Sandstone, weathered.
Thickness 1 foot
i
Calcilutite, medium-gray,
N5, weathers medium-light-
gray, N6, massive.
Thickness 1 foot
Sandstone, weathered.
Thickness 1 foot
Description and Sample
Thickness No.
Description and
Thickness______
Stratigraphic
Sample Distance
No. Above Base
(Feet)
Calcilutite, medium-
9 330
gray, N5> weathers
medium-light-gray, N6,
massive; contains small
chert nodules.
Thickness 1 foot
Sandstone, weathered.
Thickness 3 feet
Calcilutite, medium-gray,
N5* weathers medium-light-
gray, N6, massive.
Thickness 2 feet
Sandstone, weathered.
Thickness 1 foot
Calcilutite, medium-gray,
N5> weathers medium-light-
gray, U6, massive; contains
calcite veins.
Thickness 2 feet
Sandstone, weathered
Thickness 1 foot
Calcilutite, medium-dark
gray, N4, weathers medium-
light-gray, N6, massive to
thick-bedded.
Thickness 1 foot
Sandstone, weathered.
Thickness 1 foot
Unit
No.
32
31
30
29
28
27
26
25
116
Stratigraphic
Description and Sample Distance
Thickness No. Above Base
TTeeTJ
Calcilutite, medium-
grav, N5, weathers medium-
light -gray, N6, massive.
Thickness 0.5 foot
Sandstone, weathered.
Thickness 0.5 foot
Calcilutite, medium-
gray, N5» weathers medium-
light-gray, N6, massive.
Thickness 1 foot
Sandstone, weathered.
Thickness 0.5 foot
Calcilutite, medium-dark-
gray, N4, weathers medium-
gray, N5> massive.
Thickness 1 foot
Sandstone, weathered.
Thickness 0.5 foot
Calcilutite, medium-gray,
N5* weathers medium-light-
gray, N6, massive.
Thickness 2 feet
Sandstone, weathered.
Thickness 1 foot
jtJnit
I Ho,
24
I
I
i 23
22
I
21
I
|
| 20
i
i
i
j
I
j 19
18
i
!
I
17
Sample
No.
Calcilutite, medium-
gray, weathers medium-
light-gray, N6, massive;
contains minor amounts
of silty quartz.
Thickness 1 foot
Sandstone, weathered.
Thickness 1 foot
Calcilutite, medium-
dark-gray, N4, weathers
medium-gray, N5> massive;
contains calcite veins.
Thickness 2 feet
Sandstone, weathered.
Thickness 1 foot
Calcilutite, medium-dark-
gray, N4, weathers medium-
gray, N5> massive to thick-
bedded .
Thickness 1 foot
Sandstone, weathered.
Thickness 2 feet
Calcilutite, medium-gray,
N5, weathers light-gray,
N7, massive.
Thickness 2 feet
Sandstone, weathered.
Thickness 2 feet
Description and
Thickness
117 |
Stratigraphic
Distance ;
Above Base j
(Feet) |
Unit
No.
16
15
14
13
12
11
10
9
118
Stratigraphic
Description and Sample Distance
Thickness No. Above Base
(Feet)
Calcilutite, medium-
gray, N5> weathers medium-
light-gray, N6, massive,
resistant.
Thickness 1 foot
Sandstone, weathered.
Thickness 1 foot
Calcilutite, medium-gray,
N5» weathers light-gray,
N7, massive, resistant.
Thickness 2 feet
Calcilutite, medium-gray,
N5> weathers light-gray,
N7, massive, relatively
non-resistant.
Thickness 10 feet
Calcilutite, dark-gray,
N3» weathers medium-gray,
N5» thick-bedded; rela
tively resistant.
Thickness 2 feet
Sandstone, weathered.
Thickness 2 feet
Calcilutite, dark-gray,
N3, weathers medium-dark-
gray, N4, massive,
resistant.
Thickness 3 feet
Sandstone, weathered.
Thickness 3 feet
119
Unit
No.
8
7
6
5
4
Description and Sample
Thickness No.
Calcilutite, medium- 7
dark-gray, N4, weathers 6
medium-gray, N5> mas
sive to thick-bedded,
in part laminated and
cross-bedded. Contains
brachiopods, crinoids,
and abundant faecal pel
lets. Samples are badly
fractured and contain
calcite veins.
Thickness 72 feet
Calcilutite, medium-gray,
N5» weathers light-gray,
N7, medium-bedded, rela
tively non-resistant;
contains chert nodules.
Thickness 13 feet
Calcilutite, medium-gray,
N5, weathers medium-light-
gray, N6, contains laminae
and cross beds of very
fine-quartzose sand; some
laminae are replaced by
chert.
Thickness 3 feet
Sandstone, weathered.
Thickness 7 feet
Calcilutite, medium-gray,
N5, weathers medium-light-
gray, N6, thick-bedded.
Stratigraphic
Distance
Above Base
('Feet' 5
250
220
Thickness 3 feet
■ 120 i
! I
! Stratigraphic i
! Unit Description and Sample Distance j
! No. Thickness ____ No. Above Base
! (Feet) I
I
3 Sandstone, quartzose, 5 170 I
I pale red, 10R6/2, very
! fine-grained; contains
! hematite.
i
! Thickness 40 feet
Disconformity.
Base of Pennsylvanian
Bird Spring Group
(incomplete)•
Mlssisslppian
Monte Oristo
Limestone
Yellow Pine
Limestone Member
2 Calcilutite, medium- 4 130
dark-gray, N4, weathers
3
90
medium-gray, N5> massive 2 50
to thick-bedded; con
tains minor amounts of
crinoids, brachiopods,
and corals. Also con
tains chert nodules and
calcite veins.
Thickness 124 feet
The contact with the
underlying Arrowhead
Limestone Member is con
formable .
Arrowhead Limestone
Member
Unit
No.
1
121
Description and Sample
Thickness No.
Calcilutite, grayish 1
blue, 5PB5/2, weathers
dark-gray, N3> massive;
contains corals and
brachiopods.
Thickness 18 feet
Stratigraphic
Distance
Above Base
(Feet)
APPENDIX B
POINT COUNT DATA MATRIX
122
123
APPENDIX B
POINT COUNT DATA MATRIX
Variable Sample Number
IA is
2A 2B
1.
Algae 002 002 001 002
2. Brachiopods 000 001 001 001
3. Bryozoans 000 000 000 000
4. Corals 000 001 000 000
5.
Crinoids
003
001 000 001
6. Echinoids 000 000 000 000
7.
Pusulinids 000 000 000 000
8. Arenaceous forams 000 000 000 000
9.
Gastropods 000 000 000 000
10. Ostracodes 000 000 000 000
11. Sponge spicules 000 000 000 000
12.
Detrital quartz 000 000 000 000
13.
Trilobites 000 000 000 000
14. Intraclasts 000 000 000 000
15.
Pellets 000 000 000 000
16. Oolites 000 000 000 000
17.
Micrite 345 345
348 346
18. Sparry calcite 000 000 000 000
19.
Dolomite 000 000 000 000
20. Chert 000 000 000 000
21. Hematite 000 000 000 000
22. Pyrite 000 000 000 000
23. Secondary quartz 000 000 000 000
24. Insoluble residue
weight percent* 1.4 1.4
* One analysis per sample
124
Variable Sample Number
3A 3B 4a 4b
1. Algae 000 000 000 002
2. Brachiopods 000 000 000 000
3.
Bryozoans 000 000 000 000
4. Corals 000 000 000 001
5.
Crinoids 003 000 001
005
6. Echinoids 000 000 000 000
7.
Pusulinids 000 000 000 000
8. Arenaceous forams 000 000 000 000
9.
Gastropods 000 000 000 000
10. Ostracodes 000 000 000 000
11. Sponge spicules 000 000 000 000
12. Detrital quartz 000 000 000 000
13. Trilobites 000 000 000 000
14. Intraclasts 000 000 000 000
15.
Pellets 000 000 000 000
16. Oolites 000 000 000 000
17. Micrite 347 350 347
341
18. Sparry calcite 000 000 000 000
19.
Dolomite 000 000 000 000
20. Chert 000 000 000 000
21. Hematite 000 000 002 001
22. Pyrite 000 000 000 000
23. Secondary quartz 000 000 000 000
24. Insoluble residue
weight percent* 2.4 2.8
* One analysis per sample
125
Variable Sample Number
i
j
5 4
5 1
6A 6B
1.
Algae
005
000 Oil
005
2. Brachiopods 000 000 000 000
3.
Bryozoans 000 000 000 000
4. Corals 000 000 000 000
5.
Crinoids 000 000 004 006
6. Echinoids 000 000 001 000
7. Pusulinids 000 000 000 000
8. Arenaceous forams 000 000 000 000
9.
Gastropods 000 000 000 000
10. Ostracodes 000 000 000 000
11. Sponge spicules 000 000 000 002
12. Detrital quartz
207 208 000 000
13. Trilobites 000 000 000 000
14. Intraclasts 000 000 000 000
15.
Pellets 000 000 122
125
16. Oolites 000 000 000 000
17. Micrite
023
045 212 212
18. Sparry calcite 000 000 000 000
19. Dolomite 000 000 000 000
20. Chert 000 000 000 000
21. Hematite
051
012 000 000
22. Pyrite 000 000 000 000
23. Secondary quartz 000 000 000 000
24. Insoluble residue
weight percent#
91
.8
1.9
* One analysis per sample
126!
Variable Sample Number
7A 7B 8A 8B
1. Algae 001 000 000 000
2. Brachiopods 000 000
005 003
3.
Bryozoans 000 000 000 000
4. Corals 000 000 000 000
5.
Crinoids 000 000 000 000
6. Echinoids 000 001 000 000
7.
Fusulinids 000 000 000 000
8, Arenaceous forams 000 000 000 000
9. Gastropods 000 000 000 000
10. Ostracodes 000 000 000 000
11. Sponge spicules 001 000 000 000
12. Detrital quartz 000 001 Oil 004
13. Trilobites 000 000 000 000
14. Intraclasts 000 000 000 000
13.
Pellets
085 085
000 000
16. Oolites 000 000 000 000
17.
Micrite
263 263
334 342
18. Sparry calcite 000 000 000 000
19.
Dolomite 000 000 000 000
20. Chert 000 000 000 000
21. Hematite 000 000 000 000
22 • Pyrite 000 000 000 000
23. Secondary quartz
000 000 000 000
24. Insoluble residue
weight percent* 3.0 12.8
* One analysis per sample
127 !
Variable Sample Number
2A 9B 10A 10B
1, Algae 000 000 028
025
2. Brachiopods 002 004 006
005
3.
Bryozoans 000 000 049 036
4. Corals 000 000 000 000
5.
Crinoids 000 000 002 002
6. Echinoids 000 000 000
003
7. Fusulinids 000 000 001
003
8. Arenaceous forams 000 000 003
004
9.
Gastropods 000 000 000 000
10. Ostracodes 000 000 000 000
11.
Sponge spicules 000 000 000 000
12. Detrital quartz
003
001 000 000
13.
Trilobites 000 000 000 000
14* Intraclasts 001 000 000 000
15.
Pellets 000 000 000 000
16. Oolites 000 000
005 005
17.
Micrite 344
345 027
022
18. Sparry calcite 000 000
091 105
19.
Dolomite 000 000 138
119
20. Chert 000 000 000 000
21. Hematite 000 000 000 000
22. Pyrite 000 000 000 000
23. Secondary quartz 000 000 000 000
24. Insoluble residue
weight percent*
4.3 2.9
* One analysis per sample
128
Variable Sample Number
11A 11B 12A 12B
1. Algae 001 000
007 009
2. Brachiopods 000 006 003 003
3.
Bryozoans 000 000 000 000
4. Corals 000 000 000 002
5.
Crinoids 005
022
003
014
6. Echinoids 001 004 000
007
7.
Fusulinids Oil
005
000 002
8. Arenaceous forams 004 001 000 000
9.
Gastropods 000 000 000 000
10. Ostracodes 002 004 000 000
11. Sponge spicules 000 000 000 001
12. Detrital quartz 000 000 000 000
13.
Trilobites 000 000 000 000
14. Intraclasts 000 000 001 000
15*
Pellets 017
021 000 000
16. Oolites 000 000 000 000
17.
Micrite 308 288 324 310
18. Sparry calcite 000 000 000 000
19*
Dolomite 000 000 005
000
20. Chert 000 000 007
000
21. Hematite 000 000 000 000
22. Pyrite 000 000 000 000
23*
Secondary quartz 001 000 000 000
24. Insoluble residue
weight percent*
6.3 9.5
* One analysis per sample
129
Variable Sample Humber
1?A 13B 14A 14B
1. Algae 000 001 000 000
2. Brachiopods 000 000 002 001
3. Bryozoans 000 000
005
002
4. Corals 000 000 000 002
5. Crinoids 000 000 004
003
6. Echinoids 000 000 004 001
7.
Fusulinids 000 000 000 000
8. Arenaceous forams 000 000 000 000
9.
Gastropods 000 000 000 000
10. Ostracodes 000 000 000 000
11. Sponge spicules 004 000 000 000
12. Detrital quartz 038 034
003
004
13. Trilobites 000 000 000 000
14. Intraclasts 000 000 000 000
15.
Pellets 000 000 098
105
16. Oolites 000 000 000 000
17. Micrite 308
315 233
232
18. Sparry calcite 000 000 000 000
19.
Dolomite 000 000 000 000
20. Chert 000 000 000 000
21. Hematite 000 000 000 000
22. Pyrite 000 000 000 000
23. Secondary quartz 000 000 000 000
24. Insoluble residue
weight percent* 16
.3
5.2
* One analysis per sample.
Variable Sample Humber
15A 15B 16a
1. Algae 023 031 007
2. Brachiopods 000 002 002
3.
Bryozoans 000 000
003
4. Corals 003
002 001
5.
Crinoids 002 001 024
6. Echinoids 009 007
00 6
7.
Fusulinids 001 000 000
8. Arenaceous forams 000 000 001
9.
Gastropods 000 000 000
10. Ostracodes 000 000 000
11. Sponge spicules 000 000 002
12. Detrital quartz 002 000 000
13.
Trilobites 000 002 000
14. Intraclasts 000 000 00 6
15.
Pellets 039 049 000
16. Oolites 000 000 000
17.
Micrite 270
255 167
18. Sparry calcite 000 000 000
19.
Dolomite 000 000 001
20. Chert 000 000 130
21. Hematite 000 000 000
22. Pyrite 000 000 000
23.
Secondary quartz 000 000 000
24. Insoluble residue
weight percent** 7.7
16B*
0
* Sample altered to chert.
** One analysis per sample.
Variable Sample Humber
17A 17B 18A 18B
1. Algae 002 000
003
006
2. Brachiopods 003 003 007 002
3.
Bryozoans 000 003 003
002
4. Corals 001 001 000 000
5.
Crinoids 003
006
031
Oil
6. Echinoids 001 000 012 023
7.
Fusulinids 000 000 000 000
8. Arenaceous forams 000 000 000 000
9. Gastropods 000 000 000 000
10. Ostracodes 000 000 000 004
11. Sponge spicules 000 000
003
001
12. Detrital quartz
005
004
035 037
13.
Trilobites 000 000 001 001
14. Intraclasts 000 000 000 000
15.
Pellets 038 012
039
038
16. Oolites 000 000 000 000
17.
Micrite 29 6 315
211 221
18. Sparry calcite 000 000 000 004
19.
Dolomite 000 000 000 000
20. Chert 000 003 000 000
21 • Hematite 000 000 000 000
22. Pyrite 000 000 000 000
23.
Secondary quartz 000 000 000 000
24. Insoluble residue
weight percent* 6.6
18.3
* One analysis per sample.
132
Variable Sample Number
1?A 19B 20A 20B
1. Algae 001 001 001 002
2. Brachiopods 000 005 003 001
3.
Bryozoans 000 000 001 001
4. Corals 000 000 002 001
5.
Crinoids 016
017
066
035
6. Echinoids
005
004
013
018
7.
Fusulinids 000 000 003 003
8. Arenaceous forams 000 000 000 000
9.
Gastropods 000 000 000 000
10. Ostracodes
003
001
005
004
11. Sponge spicules 000 000 000 001
12. Detrital quartz 005 009
001 001
13.
Trilobites 000 000 000 000
14. Intraclasts 000 000 000 000
15.
Pellets
009 012 008 008
16. Oolites 000 000 000 000
17.
Micrite
307 299
246 274
18. Sparry calcite 000 000 001 001
19.
Dolomite 000 000 000 000
20. Chert 004
003
000 000
21. Hematite 000 000 000 000
22. Pyrite 000 000 000 000
23. Secondary quartz 000 000 000 000
24. Insoluble residue
weight percent*
15.3 5.9
* One analysis per sample.
133
Variable Sample Number
21A 21B 22A 22B
1. Algae 004
003
010
009
2. Brachiopods 001 000 001 001
3. Bryozoans 000 000 000 000
4. Corals 000 000 000 000
5.
Crinoids 000
003
072
053
6. Echinoids 003 009 009 015
7.
Fusulinids 000 000 001 002
8. Arenaceous forams 000 000 000 000
9.
Gastropods 000 000 000 000
10. Ostracodes 001 001 002 002
11. Sponge spicules 000 000 000 000
12. Detrital quartz 005 003
001 002
13.
Trilobites 000 000 000 000
14. Intraclasts 000 000 000 000
15.
Pellets 058
053 029 030
16. Oolites 003
000 001 002
17.
Micrite
275
276 163 194
18. Sparry calcite 000 000 061 040
19.
Dolomite 000 000 000 000
20. Chert 000 000 000 000
21. Hematite 000 000 000 000
22. Pyrite 000 000 000 000
23. Secondary quartz 000 000 000 000
24. Insoluble residue
weight percent* 6.5
5.0
* One analysis per sample.
134
Variable Sample Number
23A 23B 24A 24B
1. Algae 000 000 001 000
2. Brachiopods 000 000 000 000
3.
Bryozoans 000 000 000 000
4. Corals 000 000 000 000
5.
Crinoids 000 000 001 001
6. Echinoids 000 000 000 000
7.
Fusulinids 000 000 000 000
8. Arenaceous forams 000 000 000 002
9.
Gastropods 000 000 000 000
10. Ostracodes 000 000 000 000
11.
Sponge spicules 000 000 000 000
12. Detrital quartz 010
003
000 000
13.
Trilobites 000 000 000 000
14. Intraclasts 000 000 000 000
15.
Pellets 000 000 001 002
16. Oolites 000 000 000 000
17. Micrite 340
347 347
344
18. Sparry calcite 000 000 000 000
19.
Dolomite 000 000 000 000
20. Chert 000 000 000 000
21. Hematite 000 000 000 000
22. Pyrite 000 000 000 000
23. Secondary quartz 000 000 000 000
24. Insoluble residue
weight percent* ro
o
•
1 2.1
* One analysis per sample.
Variable
1. Algae
2. Brachiopods
3. Bryozoans
4. Corals
5. Crinoids
6. Echinoids
7. Fusulinids
8. Arenaceous forams
9. Gastropods
10. Ostracodes
11. Sponge spicules
12. Detrital quartz
13. Trilobites
14. Intraclasts
15. Pellets
16. Oolites
17. Micrite
18. Sparry calcite
19. Dolomite
20. Chert
21. Hematite
22. Pyrite
23. Secondary quartz
24. Insoluble residue
weight percent*
135~
Sample Humber
2^B 26A 26b
001 000 000
006 000 000
000 000 000
000 000 000
008 000 000
006 000 001
000 000 000
000 000 000
000 000 000
001 000 000
000 000 000
001
133
130
000 000 000
000 000 000
006 000 004
000 000 000
331 202
203
000 000 000
000 000 000
000 000 000
000 000 000
000
015
012
000 000 000
2.4 58.5
25A
000
000
000
000
010
001
000
000
000
001
000
001
000
000
020
000
317
000
000
000
000
000
000
* One analysis per sample.
136
Variable Sample Number
27 A 27B 28A 28B
1. Algae 000 001 000 000
2. Brachiopods 003
001 000
003
3.
Bryozoans 001 000 000 000
4. Corals 001 000 000 002
5.
Crinoids 004 014
007
001
6. Echinoids 002
005
000 000
7.
Fusulinids 000 000 000 001
8. Arenaceous forams 001 003 000 000
9.
Gastropods 000 001 000 000
10. Ostracodes 001 000 002 000
11. Sponge spicules 000 000 000 000
12. Detrital quartz 000 000 000 000
13.
Trilobites 000 000 000 000
14. Intraclasts 000 000 000 000
15.
Pellets Oil 008
005
004
16. Oolites 000 000 000 000
17.
Micrite
327
314 336
339
18. Sparry calcite 000 000 000 000
19.
Dolomite 000 000 000 000
20. Chert 000 000 000 000
21. Hematite 000 000 000 000
22. Pyrite 000 000 000 000
23.
Secondary quartz 000 000 000 000
24. Insoluble residue
weight percent*
8.9
3.2
* One analysis per sample.
137
Variable Sample Humber
29A 29 B JOA 30B
1. Algae 000
005
000 000
2, Brachiopods 000 001 001 000
3.
Bryozoans 000 000 000 000
4. Corals 000 000 000 000
5.
Crinoids 003
002 000 006
6. Echinoids 000 000 000 000
7. Fusulinids 003
004 000 000
8, Arenaceous forams 003
000 000 000
9.
Gastropods 000 000 000 000
10. Ostracodes 000 001 002 000
11. Sponge spicules 000 000 000 000
12. Detrital quartz 000 000 000 000
13.
Trilobites 000 000 000 000
14. Intraclasts 000 000 000 000
15.
Pellets 012 006 000 000
16. Oolites 000 000 000 000
17.
Micrite 330 331 347
344
18. Sparry calcite 000 000 000 000
19.
Dolomite 000 000 000 000
20. Chert 000 000 000 000
21. Hematite 000 000 000 000
22. Pyrite 000 000 000 000
23. Secondary quartz 000 000 000 000
24. Insoluble residue
weight percent*
2.7
2.0
* One analysis per sample.
138
Variable Sample Number
31A 31B 32A 32B
1. Algae 001 000 017 00 6
2. Brachiopods 001 001 000 000
3.
Bryozoans 000 000 000 000
4. Corals 000 000 000 000
5.
Crinoids 000 004 074
045
6. Echinoids 007
000 021 016
7.
Fusulinids
003
001 000 000
8. Arenaceous forams 000 000 002 005
9.
Gastropods 000 000 000 000
10. Ostracodes 000 000 000 006
11. Sponge spicules 000 000 000 000
12. Detrital quartz 000 000 000 000
13.
Trilobites 000 000 000 000
14. Intraclasts 000 000 000 000
15.
Pellets 001
003 025 009
16. Oolites 000 000 000 000
17. Micrite 333
341 066 106
18. Sparry calcite 000 000 145 158
19.
Dolomite 000 000 000 000
20. Chert 000 000 000 000
21. Hematite 000 000 000 000
22. Pyrite 000 000 000 000
23.
Secondary quartz 000 000 000 000
24. Insoluble residue
weight percent* 3.4 2.6
* One analysis per sample.
139
Variable Sample Humber
?3A 33B ?4A 34b
1.
Algae 001 000 000 000
2. Brachiopods 003
004 000 000
3.
Bryozoans 000 000 000 000
4. Corals 000 002 000 000
5.
Crinoids 001
007
000 001
6. Echinoids 006 002 002 001
7.
Fusulinids 000 000 001 000
8. Arenaceous forams 000 000 000 000
9.
Gastropods 000 000 000 000
10. Ostracodes 001 000 000 000
11. Sponge spicules 000 000 000 000
12. Detrital quartz 000 000 000 000
13.
Trilobites 000 000 000 000
14. Intraclasts 000 000 000 000
15.
Pellets 000 000 206
213
16. Oolites 000 000 000 000
17. Micrite
339 335
081 042
18. Sparry calcite 000 000 060 093
19.
Dolomite 000 000 000 000
20. Chert 000 000 000 000
21. Hematite 000 000 000 000
22. Pyrite 000 000 000 000
23. Secondary quartz 000 000 000 000
24. Insoluble residue
weight percent*
7.1
5.0
* One analysis per sample.
140
Variable Sample Number
3?A 35B
36A 36b
1. Algae 004 006 000 000
2. Brachiopods 000 001 000 000
3*
Bryozoans 001 001 000 000
4. Corals 000 000 000 000
5.
Crinoids 017
012 000 000
6. Echinoids Oil
007 000 000
7.
Fusulinids 000 000 000 000
8. Arenaceous forams 000 000 000 000
9.
Gastropods 000 000 000 000
10. Ostracodes 003
000 000 000
11. Sponge spicules 000 000 000 000
12. Detrital quartz 000 000
003
000
13.
Trilobites 000 000 000 000
14. Intraclasts 000 000 000 000
15.
Pellets 003 003 000 002
16. Oolites 000 000 000 000
17.
Micrite
309
320 347 348
18. Sparry calcite 002 000 000 000
19.
Dolomite 000 000 000 000
20. Chert 000 000 000 000
21. Hematite 000 000 000 000
22. Pyrite 000 000 000 000
23. Secondary quartz 000 000 000 000
24. Insoluble residue
weight percent* 2.8 8.4
* One analysis per sample.
1 4 1
Variable Sample Number
37A 37B 38a 38B
1.
Algae 000 000 000 000
2. Brachiopods 000 000 002 000
3.
Bryozoans 000 000 001 000
4. Corals 000 000 000 000
5.
Crinoids 000 000 002 000
6. Echinoids 000 000 001 000
7. Fusulinids 000 000 000 000
8. Arenaceous forams 000 000 000 000
9. Gastropods 000 000 000 000
10. Ostracodes 000 000 003
000
11. Sponge spicules 000 000 001 000
12. Detrital quartz 000 002 002 000
13. Trilobites 000 000 001 000
14. Intraclasts 000 000 000 000
15.
Pellets 000 000 000 000
16. Oolites 000 000 000 000
17. Micrite 348 348
339
350
18. Sparry calcite 002 000 000 000
19.
Dolomite 000 000 000 000
20. Chert 000 000 000 000
21. Hematite 000 000 000 000
22. Pyrite 000 000 000 000
23-
Secondary quartz 000 000 000 000
24. Insoluble residue
weight percent* 10.0 74.4
* One analysis per sample.
142
Variable Sample Number
39A 39B 40A 40B
1. Algae 000 000 001 000
2. Brachiopods 000 000 000 000
3.
Bryozoans 000 000 000 001
4. Corals 000 000 000 000
5. Crinoids 000 000 000 002
6. Echinoids 000 000 001 000
7. Fusulinids 000 000 001 020
8. Arenaceous forams 000 000 000 000
9.
Gastropods 000 000 000 000
10. Ostracodes 000 000 001 000
11. Sponge spicules 000 000 000 000
12. Detrital quartz 000 000 000 004
13.
Trilobites 000 000 000 000
14. Intraclasts 000 000 000 000
15.
Pellets 000 000 002 000
16. Oolites 000 000 000 000
17. Micrite 350 350 343 322
18. Sparry calcite 000 000 000 000
19.
Dolomite 000 000 000 000
20. Chert 000 000 000 000
21. Hematite 000 000 000 000
22. Pyrite 000 000 000 000
23. Secondary quartz 000 000 000 000
24. Insoluble residue
weight percent* 58.7 6.7
* One analysis per sample
1
143 j
Variable Sample Humber
I
41A 41B 42A 42B !
1. Algae 002 000
003 000
2. Brachiopods 000 002 000 002 !
3. Bryozoans 000 000 000 000 !
4. Corals 000 000 000 001
5.
Crinoids 001 000
003 001
6. Echinoids 000 000 000 002 !
7. Fusulinids 000 000 000 001
8. Arenaceous forams 000 000 000 000
1
1
9.
Gastropods 000 000 000 000
10. Ostracodes 000 000 001 000
11. Sponge spicules 000 000 000 000
j
12. Detrital quartz 000 001 000 001
13.
Trilobites 000 000 000 000
14. Intraclasts 000 000 000 000
15.
Pellets 000 000 000 000
16. Oolites 000 000 000 000
17. Micrite 347 347 343 342
18. Sparry calcite 000 000 000 000
19. Dolomite 000 000 000 000
20. Chert 000 000 000 000
21. Hematite 000 000 000 000
22. Pyrite 000 000 000 000
23. Secondary quartz 000 000 000 000
24. Insoluble residue
weight percent* 11.2
32.3
* One analysis per sample.
Variable
1. Algae
2. Brachiopods
3* Bryozoans
4. Corals
5. Crinoids
6. Echinoids
7. Fusulinids
8. Arenaceous forams
9. Gastropods
10. Ostracodes
11. Sponge spicules
12. Detrital quartz
13. Trilobites
14. Intraclasts
15* Pellets
16. Oolites
17. Micrite
18. Sparry calcite
19. Dolomite
20. Chert
21. Hematite
22. Pyrite
23. Secondary quartz
24. Insoluble residue
weight percent#
144 |
Sample Number
4JB 44A 44B
000 001
007
001 001 001
000 000 000
000 000 000
000 000 001
001 000 000
001 000 000
008 010 001
000 000 000
000 004 001
000 000 000
000 000 001
000 000 000
000 000 000
006
003
000
000 000 000
333 339
338
000 000 000
000 000 000
000 000 000
000 000 000
000 000 000
000 000 000
4.8 4.6
43A
000
002
000
000
001
000
005
004
000
000
000
000
000
000
003
000
335
000
000
000
000
000
000
One analysis per sample.
1451
Variable Sample Number
45A 4?B 46A
1.
Algae 000 000 001
2. Brachiopods 000 000 003
3.
Bryozoans 000 000 000
4. Corals 000 000 000
5.
Crinoids 000 000 008
6. Echinoids 000 000 002
7.
Pusulinids 000 000 000
8. Arenaceous forams 000 000 001
9. Gastropods 000 000 000
10. Ostracodes 000 000 000
11. Sponge spicules 000 000 000
12. Detrital quartz 001 000 001
13.
Trilobites 000 000 001
14. Intraclasts 000 000 000
15.
Pellets 000 000 003
16. Oolites 000 000 000
17.
Micrite 349 350 330
18. Sparry calcite 000 000 000
19.
Dolomite 000 000 000
20. Chert 000 000 000
21. Hematite 000 000 000
22. Pyrite 000 000 000
23. Secondary quartz 000 000 000
24. Insoluble residue
weight percent** 13.2
46B*
20.7
* Sample altered to chert
** One analysis per sample
146
Variable Sample Number
1
!
i
47 A 47B 48A 48B
1. Algae 000 000 000 000 !
2. Brachiopods 003
002 000 000 !
3.
Bryozoans 000 000 000 000 !
4. Corals 000 000 000 000 I
5.
Crinoids 000 000 000 000
6. Echinoids 000 000 000 000 !
7.
Pusulinids 000 000 000 000
8. Arenaceous forams 000 000 000 000
9.
Gastropods 000 000 000 000 i
10. Ostracodes 000 000 000 000
11. Sponge spicules 000 000 000 000
12. Detrital quartz 000 000 006 004
13. Trilobites 000 000 000 000
14. Intraclasts 000 000 000 000 !
15.
Pellets 000 000 000 000
16. Oolites 000 000 000 000
17. Micrite 344
345
342
343
18. Sparry calcite 000 000 000 000
19. Dolomite 000 000 000 000
20. Chert 000 000 000 000
21. Hematite 000 000 000 000
22. Pyrite 000 000 000 000
23. Secondary quartz 000 000 000 000
24. Insoluble residue
weight percent* 12.2 49.7
* One analysis per sample.

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Asset Metadata

Creator McDougall, Donald Stewart (author)

Core Title Carbonate microfacies of the Upper Monte Cristo Limestone and the Lower Bird Spring Group at Mountain Springs, Clark County, Nevada

Degree Master of Science

Degree Program Geological Sciences

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

Tag OAI-PMH Harvest,Sedimentary Geology

Language English

Contributor Digitized by ProQuest (provenance)

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c30-112697

Unique identifier UC11225557

Identifier usctheses-c30-112697 (legacy record id)

Legacy Identifier EP58571.pdf

Dmrecord 112697

Document Type Thesis

Rights McDougall, Donald Stewart

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