CALIFORNIA STATE UNIVERSITY, NORTHRIDGE
DEPOSITIONAL ENVIRONMENTS OF THE EOCENE
DOMENGINE FORMATION NEAR COALINGA,
FRESNO COUNTY, CALIFORNIA
A thesis submitted in partial satisfaction of the requirements for the degree of Master of Science in
Geology
by
Kathleen Ann Roush
May, 1986 The Thesis of Kathleen Ann Roush is approved:
L. Squires
California State University, Northridge
ii ACKNOWLEDGEMENTS
The writer would like to thank Drs. A. Eugene Fritsche, Richard
Squires, and Stephan Graham for critically reviewing the manuscript and their constructive advise and guidance in completing this project. Special thanks to the Harris Feeding Company for allowing access to the type area and to Loretta Martin for typing the thesis. The writer would also like to thank Alan Hershey who analyzed the microfossil samples.
Special appreciation is directed to James Roush for his help and patience.
iii TABLE OF CONTENTS
PAGE
Acknowledgements iii
List of Illustrations ...... vii
Tables ...... ix
Abstract ...... x
Introduction ...... 1
Purpose ...... 1
Location and Accessibility 1
Previous Work ...... 4
Methods ••••••••....•••....•.••.•.•.•..••.•••.•.••••.•••...••.•.••••••.•••.•••••••.••• 4
Geologic Setting 22
Structure ...... 2 2
Stratigraphy...... 25
Lithosomes and Depositional Environments 29
Introduction ...... 2 9
Coal 33
Description 33
Interpretation ...... 3 5
Carbonaceous Mudstone ...... 3 5
D~scription ...... 3 5
Interpretation 36
Cia ystone ...... ················.,.)··················· 3 8
Description ...... 3 8
iv PAGE
Interpretation ...... 3 9
Pebble Conglomerate 40
Description ...... 4 o
Interpretation ...... 4 1
Gray Sandy Mudstone 42
Description ...... 4 2
Interpretation ...... 4 2
Mudstone-Pod-Bearing Sandstone 43
Description ...... 4 3
Interpretation ...... 4 4
Ostrea-Bearing Sandstone 45
Description ...... 4 5
Interpretation 47
Coarse Sandstone 49
Description ...... 4 9
Interpretation ...... 5o
Fossiliferous Sandstone ...... 5 1
Description ...... s 1
Interpretation ...... 55
Fine Structureless Sandstone 58
Description ·····································••••••o•••••···················· 58 Interpretation ...... 59
Con glomera tic Sandstone ····················································~· 6 0
v PAGE
Description ...... 6 o
Interpretation ...... 63
Fine Sandstone ...... 6 4
Description ...... 6 4
Interpretation ...... 6 5
Sandy Mudstone ...... 66
Description ...... 66
Interpretation ...... 6 7
Glauconitic Sandstone 68
Description...... 68
Interpretation ...... 7 0
Diagenesis of the Formation 70
Paleogeography ...... 7 2
Age and Correlation ...... 7 2
Domengine-Kreyenhagen Unconformity 74 Provenance ·········································································· 76 Paleogeography 79
Climate ...... 7 9
Paleogeography .:...... 8 0
Domengine-A venal Equivalence ...... 8 4
References ...... •....•...... •.•...... ••...•..•...•...... ••...... ••..••....• 86
Appendix 1 93
Appendix 2 95
Appendix 3 ...... 9 7
vi LIST OF ILLUSTRATIONS
FIGURE PAGE
1. Index map of the study area. 2
2. General geologic map of the study area along the 3 southern Diablo Range.
3. Location of measured sections. 5
4. Explanation for measured stratigraphic sections. 7
5. Stratigraphic section of the Domengine Formation 8 measured in Coalmine Canyon, east corner section 27 and west corner section 26, T.20S., R.l4E., Alcalde Hills quandrangle, California.
6. Stratigraphic section measured on the west-facing 10 side of the Oil City Peak ridge in the southeast corner of section 17, T.l9S., R.l5E., Joaquin Rocks quadrangle, California.
7. Stratigraphic section measured on the west side of 11 Oil City Peak in the east corner of section 17, T.l9S., R.l5E, Joaquin Rocks quadrangle, California.
8. Stratigraphic section measured on the west-facing 1 2 ridge near the center of section 9, T.l9S., R.l5E., Joaquin Rocks quadrangle, California.
9. Stratigraphic section measured on the east side of 1 3 Domengine Creek, southern corner of section 29, T.l8S., R.15E., Joaquin Rocks quadrangle, California.
10. Stratigraphic section measured on the north side of 14 Salt Creek, central portion of section 1 O, T.l8S., R.l4E., Joaquin Rocks quadrangle, California.
11. Regional structure in the vicinity of the southern 23 portion of the study area.
12. Regional structure in the northern portion of the 24 study area. Outcrops of lower Tertiary sequences are indicated by the blackened areas.
vii 13. i'J'Jrth to south stratigraphic cross section along the 26 south limb of the Vallecitos Syncline. Thicknesses south of Oil Canyon are approximated.
14. Nomenclatural history of the names and ages of 30 the formations in the study area.
15. North to south cross section showing the 3 1 distribution of lithosomes in the Domengine Formation plotted versus time.
16. Lowermost coal seam within the Coalmine Canyon 34 section.
17. Coal pods within the carbonaceous mudstone 37 lithosome. Pods do not necessarily follow bedding.
18. Fossiliferous sandstone lithosome in the Oil City 52 section. A fine sandstone lithosome bed is near the top of the photo.
19. Mottled appearance of the fossiliferous sandstone 53 lithosome in the Oil City section.
20. Alpha index plot of the foraminifera of the 56 fossiliferous sandstone and sandy mudstone lithosomes.
21. Conglomeratic sandstone lithosome in the 61 Domengine Creek section.
22. The conglomeratic sandstone lithosome of Salt 61 Creek. The lithosome is interbedded with the fine structureless sandstone lithosome and shows A) channel structure and B) normal parallel-bedded structure.
23. Correlation chart of the Domengine Formation 73 with various authors tor comparison of the age assignment.
24. Ternary diagrams showing the composition of rocks 78 from the Domengine, Panoche, and Yokut Formations.
25. Paleogeography of the study area during the 82 deposition of the Domengine Formation.
26. Paleogeography of the Alcalde Hills and Reef 83 Ridge during the deposition of the Domengine Formation.
viii TABLES
TABLE PAGE
1. Petrology and field location of rock samples. 1 5
2. Heavy mineral analysis of seven samples from the 16 Domengine Formation.
3. Composition of conglomeratic samples from the 17 Domengine Formation.
4. Macrofossils from the Domengine Formation. 19
5. Microfossils from the Domengine Formation. 20
6. Lithosomes within the Domengine Formation and 32 the associated depositional environments.
ix ABSTRACT
DEPOSITIONAL ENVIRONMENTS OF THE EOCENE DOMENGINE FORMATION NEAR COALINGA, FRESNO COUNTY, CALIFORNIA
by Kathleen Ann Roush Department of Geological Sciences California State University, Northridge Northridge, California
The upper lower through lower middle Eocene Domengine Sandstone crops out in the southern Diablo Range in the Alcalde and Big Blue Hills. The formation reaches a maximum thickness of 65 m and is overlain by the deep- marine shales of the Kreyenhagen Formation. The Domengine unconformably overlies the Cretaceous Panoche Formation in the Alcalde Hills and the lower
Eocene Yokut Sandstone in the Big Blue Hills.
The Domengine in the Alcalde Hills was deposited on a fluvial-dominated delta. The formation contains interdistributary bay, swamp, distributary channel and levee, and overbank flood deposits. Distributary channel deposits consist of pebble conglomerate and cross-bedded sandstone. The associated levee deposits consist of sandy mudstone and fine-grained sandstone and contain mudstone pods and carbonaceous material. Overbank flooding between the distributaries formed claystone deposits. The beach deposits of the interdistributary bay are represented by fine-grained sandstone which contains
X cross bedding, and parallel and wavy laminations lined with carbonaceous material. Lenses of Ostrea idriaensis and other shallow water fauna are abundant. Coarse, fossiliferous sandstone deposits were formed by storms within the inter distributary bay.
North of Los Gatos Creek, in the Big Blue Hills, the base of the
Domengine is marked by a basal pebble bed. The bed represents a transgressive lag and contains abundant black chert and fossil fragments. The majority of the
Domengine consists of shoreface and transition zone deposits. The lower shoreface deposits consist of structureless (90% to 100% bioturbated) muddy sandstone and contain a wide variety of foraminifera and molluscs. Wood fragments are abundant. The middle shoreface deposits consist of predominantly structureless (70% to 90% bioturbated) fine sandstone which contains some parallel laminations. Structureless mudstone and sandy mudstone deposits represent the transition zone environment and contain foraminifera.
Storm deposits, represented by fine sandstone beds and conglomeratic sandstone, occur within the shoreface and transition zone deposits.
The deposits of the Domengine Formation were derived from a sedimentary source terrain, possibly the Paleocene and Mesozoic rocks to the west. The deposits are the result of an Eocene westward transgression across an eastward-sloping shoreline. A fluvial-dominated delta formed south of Los
Gatos Creek and there was deposition of shoreface and transition zone deposits along a rocky coastline to the north. The lack of significant interdistibutary bay and transition· zone deposits in the northern and southernmost portions of the study area indicate that there was erosion followed by quick subsidence prior to the deposition of the deep-marine shale of the Kreyenhagen Formation.
xi INTRODUCTION
PURPOSE
The Domengine Formation crops out along the Diablo Range and portions of Mount Diablo and the southern Sacramento Valley. The age and depositional environments of this formation at its southernmost extent have not been extensively studied and are the primary objective of this report.
The formation is divided into distinct lithosomes which are interpreted according to their paleontologic and sedimentologic features. A secondary objective of this report is to determine how the depositional environments found within the Avenal Formation, which crops out approximately 20 krn to the south, link up to the environments found within the Domengine
Formation. The Avenal and Domengine Formations were shown to be continuous with each other in the subsurface (Harun, 1984). The name Avenal has priority, however for the sake of clarity the name Domengine will be used throughout this report.
LOCATION AND ACCESSIBll.ITY
The southernmost outcrops of the Domengine Formation occur approximately 5 km west of· Coalinga, on the west-central edge of the San
Joaquin Valley, central California (Fig. 1). The study area includes the type section and 18 km of outcrops between Coalmine Canyon and Salt Creek (Fig.
2). Outcrops follow the general homodinal structure of the area and dip an average of 300E toward the valley (Fig. 2). The Domengine Formation is not a resistant unit and is covered by Holocene alluvium and grasses throughout
1 2
--- ...... "\ ...... ·
(/) ....! ....! /".. ~··,...·. :r \
Mop Location \ .. ,....) I ) f
/ j -··
' t _...... r··-;;-·· 0 5mi / 0 Skm
® SECTION LOCATION
Figure 1. Index map of the study area. " ' 3
0...... 30mi 0 4!5km
'<. 27
"27 ~ '. "23 '.;:,,. ' ' 1 " ~ \.26 ·"I o -----,. ..~/ 'a' I I '- \ "",' - ~ 17 ' \ ' J 20 \ \ ' ', Kp \ ~ ' 0 2 2.!5mi
0 2 4km
fl
LEGEND
Alluvium Yokut Formation ~ Holocene 6] Eocene
Landslide Lode Formation ~ Holocene ~ Paleocene - Eocene
Older Alluvium Moreno Formation ~ Pleistocene ~ Cretaceous [!;] Etchegoin Fm. Panache Fm. Pliocene MK~ Members Cretaceous §3 Santo Margarita Fm. Miocene ~ Contact Qo Temblor Formation Fault ~ Miocene ----t-" Syncline §] Kreyenhogen Fm. Eocene -r Anticline _,_ Dam engine Formation Attitude on beds ~ Eocene
Figure 2. General geologic map of the study area along the southern Diablo Range (after Dibblee, 1971a, 1971b). 4
the area. Good exposures occur in steep canyons and along slopes which are steeper than 30 to 35 degrees.
Exposures of the Domengine Formation occur on private property and permission for entry is required. Dirt roads are well maintained in the area and pass within a half kilometer of many of the outcrops. These roads have gates, however, which require a key for entry.
PREVIOUS WORK
The sequence of rocks currently referred to as the Domengine
Formation was mapped by Arnold and Anderson (1910), Anderson and Pack
(1915), Adegoke (1969), and Dibblee (1971a, 197lb). The macrofossils of the
Domengine were examined by Arnold (191 0), Arnold and Anderson (191 0), and
Vokes (1939). The paleoecology of these fossils was discussed by Vokes
(1940). The microfossils were examined by Laiming 0940a, 1940b, 1943), and
Mallory (1959). Cushman (1927) described the microfossils found in the Oil
City Peak area (Fig. 3). The depositional environments of the Domengine
Formation to the north were discussed by Cherven (1983) and Bodden (1983).
The depositional environments of the early through medial Eocene Avenal
Formation were described by Kappeler (1984) and Kappeler and others (1984).
Steinmeyer (1974) determined the ages of the Paleocene and Eocene deposits that underlie the Domengine Formation in Salt Creek.
METHODS
Six stratigraphic sections (Fig. 3) were measured by the tape-and brunton method (Appendix 1). Additional exposures between the sections 5
0 2 2.5mi 8 0 2 4 km
City Peak
LEGEND
I Measured Section ~ Domengine Sandstone Cool Seams occur between these two symbols (869) Mocrofossi I Locality
Coolmine Canyon (866, 867, 868)
6 COALINGA
Figure 3. Location of measured sections (base map same as in Fig. 2, from Dibblee, 1971a, 1971b). 6
were examined in order to locate fossil localities and any important sedimentologic features. Figure 4 shows the explanation for the drafted
measured sections shown in Figures 5 through 10. California State
University, Northridge macrofossil localities, microfossil localities, and the
locations where rocks were sampled for thin sections are shown on these sections. True stratigraphic thickness was determined trigonometrically and
checked using the orthographic procedures outlined in Ragan (1973).
Laboratory work included the examination of thin sections, heavy
minerals, conglomerate clasts, macrofossils and microfossils. It also included the determination of size distribution of selected sieved samples. Thin sections were cut from 24 rock samples (Table 1). Each slide was stained for
potassium and plagioclase feldspar and examined in order to determine composition, texture, and diagenetic history. Percent composition was determined by counting 250 points per slide using a point-count microscope attachment. Thirteen rock samples were analyzed for size distribution by sieving for 15 minutes on a Ro-tap machine. Pipette analysis was run on the six samples from the sieve analysis which contained greater than 35% silt and clay. The results of this size distribution analysis for each sample were graphed as a histogram and as cumulative-frequency curves (both probability and arithmetic ordinates). From these graphs, the median grain size, sorting, skewness, and kurtosis were calculated for each sample. The heavy minerals from seven samples were examined (Table 2). Descriptions of two conglomeratic sandstones included clast composition, shape, size, angularity, and clast-to-matrix ratio (Table 3). For each sample, a rock approximately
150 em x 100 em x 100 em was collected in the field. The rock was 7
EXPLANATION
LITHOLOGY SYMBOLS
Structureless Cool ~ Parallel Laminations .... ~:~:· .. · Cross Bedding § Shale Convolute Bedding Claystone w Channel Concretion [ill Siltstone 4../ Macrofossils Fine Sandstone D y Trace Fossil 0 Floating Clasts Medium Sandstone D Rip- up Clasts Coarse to Gronu lor Sandstone w Cool Pods ~ Pebbles Carbonized Wood Carbonaceous Material Covered, but interpreted ETI ····Z···· Laminations lined with --7:--- Carbonaceous Material
COLLECTION LOCALITIES
OC·C, DC-30 Thin Section Numbers
~ 869 CSUN Macrofossil Locality
102 8:J Microfossil Locality
~ 102 Barren Microfossil Sample Locality
Figure 4. Explanation for measured stratigraphic sec- tions. Collection Lithesome Formation Scale Lithology Localities Names Names
20
Carbonaceous Mudstone
Cool Muds-tone-Pod Bearing Sandstone ------~ 123 Claystone C/) ------=- _- cr CMC D w 10 1- ~: _:.:~~:<~·:~:·:::: DOMENGINE w .. - ...... · :::E FORMATION -:' ::~:~·:z~:~_::__-:·-:· -·-.. -_·.·- ... Gray Sandy Mudstone 5
Pebble Conglomerate 0
PANOCHE· FORMATION
CMC 16
121 .... . Y.···~·.·· . . .I...J' . . . . ··o·· . '• ·.·.- ..: :~·.:,. ::''·.:·.. o:. -- CMC B
Figure SA. Stratigraphic section of the Domengine Form ation measured in Coalmine Canyon, east corner section 27 and west corner section 26, R.20S., R.lSE., Alcalde Hills quadrangle, California. Section continued on Figure SB. 9
Collection Lithesome Formation Scale Lithology Localities Names Names
KREYENHAGEN FORMATION
Coarse Sandstone ~868
Ostreo- Bearing Sandstone ---- .G 867 ~~--~C~oo~l ______... . . :·-~.:.::~~~.. ·-~- : ·. • % .••. · •• · .. •' .. ·...... _ '-: ~_.:_. ~~- >~-~: 50 . : .· . ...6 ..... ·z. Ostreo - Bearing Sandstone
45 (/) DOMENGINE a:: w FORMATION 1- w :E -.,..~--=Cc:O.::.O:_I------
35 Carbonaceous Mudstone ----- CMC F, 125
30 Ostreo - Bearing Sandstone ••••If::'--- ~ 866 Cool -. -.
25 ----124 CMC E Carbonaceous Mudstone
20
Figure SB. Stratigraphic section of the Domengine Formation measured in Coalmine Canyon. Continued from previous page. 10
Collection Litho some Formation Scale Lithology Localities Names Names
KREYENHAGEN FORMATION Sandy Mudstone _,.,..Fine Sandstone Sandy Mudstone 15
Fossiliferous Sandstone DOMENGINE a::(J) 10 FORMATION w 1- w ~ Fine Sandstone 5
Fossiliferous Sandstone 0 YOKUT FORMATION
Figure 6. Stratigraphic section measured on the west facing side of the Oil City Peak ridge in the southeast corner of section 17, T.19S., R.15E., Joaquin Rocks quad rangle, California. 1 1
Collect ion Lithesome Formation Scale Lithology Localities Names Names
KREYENHAGEN FORMATION Sandy Mudstone Fine Sandstone 1131%> Sandy Mudstone .../Fine Sandstone (/) 10 a:: w 1- Sandy Mudstone DOMENGINE w FORMATION ~ j Fossiliferous Sgndstone ,Fine Sandstone Fossiliferous Sandstone Conglomeratic 0 Sandstone
YOKUT FORMATION
Figure 7. Stratigraphic section measured on the west side of Oil City Peak in the east corner of section 171
T. 198. 1 R. 15E. 1 Joaquin Rocks quadrangle I California. 1 2
Collection Lithesome Formation Scale Lithology Localities Names Names
KREYENHAGEN FORMATION
Sandy Mudstone
Fine Sandstone 15 Sandy Mudstone
Fine Sandstone DOMENGINE 10 Sandy Mudstone FORMATION
Fossiliferous 5 Sandstone
Fine Sandstone Fossiliferous 0
YOKUT FORMATION
Figure 8. Stratigraphic section measured on the west facing ridge near the center of section 9, T.19S., R.15E., Joaquin Rocks quadrangle, Caljfornia. 1 3
Collection Lithosome Formation Scale Lithology Localities Names Names
(glauconitic) KREYENHAGEN FORMATION
35 Glauconitic Sandstone
Fine Sandstone 30
Sandy DOMENGINE Mudstone FORMATION 25 ../Fine Sandstone
(f) 20 a:: w ;·:.. {.'.~.·:.:·.. t.::.)·::··.::.:. -115 a, 1- w ::::iE 15 ,, ;> x: .. ~~~;, :_::·.y·.<~:\:':>> {·:·:>_:·.
Fossiliferous Sandstone
5
_Ieong lomerat i c Sandstone YOKUT FORMATION
Figure 9. Stratigraphic section measured on the east side of Domengine Creek, southern corner of section 29, T.18S., R.lSE., Joaquin Rocks quadrangle, California. 1 4
Lithosome Formation Scale Lithology Names Names
KREYENHAGEN FORMATION 38.6m :Y . ·. ·.'(.... . ·. :. ·. . ·.·(.·.· 35 ...
Fine Structureless .... ·.. . ·y·· ·: .. ·.· ::: Sandstone
30 (6: .... ~.· ) ·. ····:·;::: .... : .. :·_· :_ ..
-'Conglomeratic 25 ::~.=.... ~.: :~;~·~:.:; =··.:_ -:~-;~ ·.~ \ Sandstone .·,· ...:_:.:.- .. ·· ..'cr:?..:::·:: .. · DOMENGINE .. ············ FORMATION
20 ... : .
(/) : ..... :. : .. :.: . ... ~ _:. . a::: Fine Structureless w Sandstone 1- w .. · . . . . ~ 15 , .. _/Conglomeratic ·:=$;.;;~;~·.:.~~~ Sandstone
10
Fine Structureless Sandstone
_/Conglomeratic -...... _ Sandstone YOKUT FORMATION
Figure 10. Stratigraphic section measured on the north side of Salt Creek, central portion of section 10, T.18S., R.14E., Joaquin Rocks quadrangle, California. TABLE I. PETROLOGY AND FIELD LOCATION OF ROCK SAMPLES
SAMPLE FIELD LOCATION P~I!C~NT COMPOSITION AVG. TEXT ROCK NAME
Ou Plag Orth Rf CACM OTCM OT so RD (A1ter Folk, 1974)
CMC A 26 m below base of Coal mine 23.6 11.2 18.8 8.4 24.0 2.4 11.6 M SA moderately sorted medhHn sandstone: calcitic Canyon section (Fi~. 5) submarine bil')tite-bearin~ arkose. CMC B 23 rn below bast• in Coal mine 21.2 8.8 9.6 3.2 46.0 II. 2 VP SA very poorly sorted line sandstone: calcitic C Key: Percel\t Composition; Qu:::Quaratz, Pldg::Piagioclase, Orth:::Orthodase, Rf=Rock Fragment, CACM::Calcite Cement, OTCM=Other Cement, OT.:.Other, Avg. Text.=Average TextlKe, SO::: Sorting, P~Poor, M=Moderate, W::~ell, VP::Very Poor, RD=RoiXIdness, A::: Angular, SA::Sub.lngular, SI~=Sub-rounded. \Jl 16 TABLE 2. HEAVY MINERAL ANALYSJS OF SEVEN SAMPLES FROM THE DOltENGINE FORMATJON MINERAL COMPOSmON Sample Number CMCC CMCG S3-C Cong S5-13 DC15 DC 50 Mean Lithesome PC css cs cs FS FSS FSS Percent MINERAL Magnetite 13.7 4.8 2.1 4.2 3.0 7.8 5.6 5.9 Ilmenite 33.0 24.0 1.5 14.6 3.5 8.6 3.3 12.6 Leucoxene 11.0 19.4 2.9 19.3 6.8 5.9 17.9 11.9 Limonite 30.0 23.8 84.6 10.9 72.3 65.8 39.3 46.6 Hematite 2.1 5.2 18.7 1.3 18.6 6.6 Pyrite 5.2 8.2 0.6 2.6 2.4 Muscovite 0.3 1.3 1.0 0.4 Biotite 2.6 4.1 2.0 5.5 6.7 2.1 3.3 Chlorite 1.5 0.2 Zircon 1.8 7.2 1.6 7.7 1.1 0.5 0.8 3.0 Tourmaline 0.3 1.6 0.3 1.3 0.7 1.0 0.7 Hornblende 0.4 2.6 2.0 0.8 1.7 1.9 3.3 1.8 Apatite 5.3 1.2 1.1 10.3 2.9 0.8 4.2 3.7 Garnet 2.1 1.6 0.1 0.8 0.2 0.7 Epidote 0.3 0.8 0.2 0.2 Glaucophane ------0.2 --- 0.1 tr Total Percent 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 tr =trace - not present PC = pebble conglomerate CSS = coarse sandstone CS = conglomeratic sandstone FS = fine sandstone FSS = fossiliferous sandstone SEPARATION YIELD Sample Initial Heavy Light %Heavy % Lt Percent Number Weight Min Wt. Min Wt. Minerals Minerals Loss CMCC 7.837 gm 0.060 gm 7.686 gm 0.781 99.219 1.16 CMCG 4.219 gm 0.049 gm 4.089 gm 1.196 98.804 1.92 S3-C 4.273 gm 0.102 gm 4.162 gm 2.451 97.549 0.21 Cong 4.384 gm 0.049 gm 4.334 gm 1.119 98.881 0.09 S5-13 10.727 gm 0.051 gm 10.581 gm 0.482 99.518 0.89 DC 15 6.837 gm 0.032 gm 6.771 gm 0.473 99.527 0.50 DC 50 12.592 gm 0.006 gm 12.134 gm 0.049 99.951 3.59 1 7 TABLE3. CONGLOMERATE CLAST ANALY~ OF THE DOMENGINE FORMATION Sample: S5-Congl. Composition % No. Diam. Rg. Ave. Shape Roundness Black Chert 71% 87 4-12 mm 8mm equant sub rded Gray Chert 18% 22 3-10 mm 7mm equant sub rded Sandstone 3% 3 1-7 mm 2mm equant sub ang Granite 2% 2 7-10 mm 8mm prolate sub rded Quartzite 3% 4 2-7 mm 3mm equant rounded Red Chert 3% 3 4-9 mm 6mm equant sub rded Sample: SC-1 Composition % No. Diam. Rg. Ave. Shape Roundness Black Chert 73% 50 6-52 mm 21 mm equant sub rded Quartzite 18% 12 15-37 mm 24 mm equant sub rded Gray Chert 4% 3 20-31 mm 20 mm equant sub rded Red Chert 3% 2 9-20 mm 15mm equant sub rded Sandstone 1% 1 20mm 20 mm equant rounded Gneiss 1% 1 28mm 28mm equant sub rded Sample: CMC C Composition % No. Diam. Rg. Ave. Shape Roundness Black Chert 59% 304 3-35 mm 8mm equant sub rded Sandstone 24% 129 3-23 mm 10 mm oblate sub rded Quartzite 11% 52 2-20 mm 10 mm . equant sub rded Schist 3% 13 5-10 mm 7mm equant rounded Shale 3% 13 5-22 mm 10 mm oblate sub rded 18 disaggregated in the laboratory and sieved through a -1.5 phi sieve. Any clasts greater than -1.5 phi (approximately 3 mm in diameter) were analyzed for composition. Macrofossils were collected from thirteen localities (Table 4). These localities are listed and described in Appendix 2. The fossils were curated and identified with the help of R. L. Squires and are stored at CSUN. Twenty-five fine-grained rock samples were collected from various locations within the Domengine (Appendix 3). These samples were disaggregated and analyzed for the presence of siliceous and calcareous microfossils. Nine samples contained benthonic and planktonic foraminifera (Table 5). Approximately 300 to 400 specimens were picked per sample and mounted on slides. Distinctive species were identified by Alan Hershey, consulting biostratigrapher. The foraminifera were analyzed by the author in order to determine the paleoecology. Two samples contained highly recrystallized radiolaria in addition to the foraminifera. Permanent slides were made of these samples, however, these radiolaria were too poorly preserved to be identified to any degree of certainity. Lithologic colors are based on the Geological Society of America color chart developed by Goddard (1980). Grain size is from Wentworth (1982), rounding from Powers (1953), and grain shapes are based on Zingg (1953). Environmental definitions and nomenclature are based on Reineck and Singh (1975). Rock names, sorting, and maturity are based on Folk (1974). 19 TABLE 4. MACROFOSSll.. FAUNAL LIST C.S.U.N... LOCALITIES DC ~ SA..: CMC • oc MACROFOSSll..S 0 - N ... .. 0 "' .. "' "' .. ...- ... N .."' .."' .."' ...... , .. ..., ~ ::g .,"' .,... ., .. SCAPHOPODA Denta!ium sp. X X GASTROPODA Calyptraea diegoana (Conrad) X )( Crepidula sp. X Crommium andersoni (Dickerson) X Ficopsis remondii crescentensis Weaver and Palmer X ?Fusinus sp. X Neverita sp. X Odostomia griswoldensis Vokes X Turritella anderstoni lawsoni Dickerson X Turritella bulwaldana Dickerson X Turritella uvasana aedificata Merriam X X X Turritella uvasana aedificata? Merriam X X Turritella uvasana subsp. X Turritella sp. X cerithid X unidentified gastropods l( unidentified gastropod n. sp.? l( BIVALVIA Barbatia (Obliquarca) morsei? Gabb X Crassatella uvasana? Conrad X Glycymeris (Glycymerita) sagittata Gabb X X Glycymeris sp. X Macrocallista (Costacallista) domenginica? Vokes X X Nemocardium linteum (Conrad, 1855) X ?Nemocardiumsp:-- X Ostrea idriaensis Gabb X X X X X Pitar {Calpitaria) campi Vokes X X Pitar sp. X X X Selena sp. X X Spisula sp. X X Venericardia {Glyptoactis) domenginica Vokes X X X X Venericardia (Pacificor) hornii calafia? Stewart )( pit arid X unidentified bivalves X X X X X X ECHINODERMATA Schizaster diabloensis Kew X Key: DC = Domengine Creek, SA = Section A, CMC = Coalmine Canyon, OC = Oil City, * =between section B and Oil City, ** =between Domengine Creek and Section B. TABLE 5: MICROFOSSll.. FAUNAL LIST LOCALITIES SB SA DC oc MICROFOSSll..S "' (I)~ ~ -0 "'0 ..0 0 "'2 ~ = ~ FORAMINIFERA ? Amehistegina sp. X Anomalina coalingensis Cushman and Hanna X X X X X X X b_. d. b_. coalingensis Cushman and Hanna " X X X X X X A. keenae Martin .. >\ X X X X X A. d. A. keenae Martin X A. welleri (Plummer) X Anomalina sp. X X X X Bathysiehon eocenica Cushman and Hanna X Bath:tsiehon sp. X Bolivina cf. B. thomsoni X Bulimina d.~. eueoides d'Orbigny X ~· eueoides d'Orbigny X Bulimina sp. X Cibicides e~nidiformis (Martin) X X £· each:tderma (Rzehak) X X X X X X £· sandiegensis Cushman and Hanna X £. d. £. sandiegensis Cushman and Hanna X X )( C. whitei var. Martin X X Cibicides sp. X X Cibicidoides venezuelanus? (Nuttall) X Cydammina coalingensis (Cushman and Hanna) X C. cf. C. sim1ensis Cushman and McMasters X Dentalina d. _Q. aperoximata Reuss X Dentalina sp. X X X Discorbis coalingensis (Cushman and Hanna) X X X X Elliesonodosaria cocoaensis (Cushman) X Elehidium hanni var. X X E. smithi Cushman and Dusenbury X E~nides lodoensis Martin X X X X X X E. mexicana (Cushman) X X X X X X g. d.~· erimus Martin X Eeonides sp. X x. X Gaudryina cf. ~· jacksonensis Cushman Gaudr:tina sp. X X X X Globigerina bakeri Cole X X G. bulloides d'Orbigny X X X X X G. triloculinoides Plummer X Globoratalia aragonensis Nuttall X X X G. crassata (Cushman) X X G. d. G. crassata (Cushman) X X X G. nicOli Martin X G. d. G. nicoli Martin X X Globoratalia sp. X Gumbelina globulosa X Gyroidina danvillensis X G. orbicularis d'Orbigny X X g:. soldanii var. X ' . 2 1 LOCALITIES SB SA DC oc -0 0"' ..0 0"' "'0 "'0 - ~ ~!! ~ '- Gyroidina sp. l< Lagena d. h· substriata Williamson X Lagena sp. X X Lenticulina sp. X Marginulina cf. M· bull at a Reuss X M. subbullata Hantken X X M. cf. M. subbullata Hantken X Nodogenerina d. ~· consobrina X X ~· kressenbergensis {Gumbel) X ~· d.~· kressenbergensis (Gumbel) X Nodosaria arundinea Schwager X ~· COnSJ2UfCata X N. latejugata Gumbel X X X X X Nodosaria sp. X X X X Nodosaria chamber X Nonien J2lantum Cushman and Thomas X Nonionella sp. X Pseudoglandulina cf. !:· ovata (Cushman & Applin) X X Pseudoglandulina sp. X Pullenia? guingueloba (Reuss) X !:· salsburyi Stewart and Stewart )( X X X Robulus ~eudomamiligera var. X B· cf. B:· J2Seudomamiligera X X B· d. B· terryi Coryell and Embich X R. cf. R. welchi var. Robulus s-p-.-- X X X X X X X X Saracenaria sp. )( SiJ2honina umbilicatulus X S. wilcoxensis Cushman and Garrett X X X Textularia mississiJ2J2iensis Cushman X X Tritaxia sp. )( X X X X X X Uvigerina sp. X Vaginulinopsis cf. V. nudicostati3. X X X X X X y. saundersi (Hanna and Hanna) )( X V. cf. V. vacavillensis (G. Hanna) X VaginuTinoJ2sis sp. X X X OT HER FAUNAL MATERIAL Fish Teeth X X Ostracods (smooth) X X X Ostracods (ornamented) X X X X X Radiolaria X X X X X Recrystalized Foraminifera .• X Poorly Preserved Foraminifera X Key: SA = Section A, SB = Section B, OC = Oil City, DC= Domengine Creek. 22 GEOLOGIC SETTING Structtre The Domengine Formation crops out along the Alcalde Hills and Big Blue Hills on the east side of the Diablo Range (Fig. 11). The Domengine outcrop wraps partially around the Coalinga anticline and continues northward through the Big Blue Hills into the Vallecitos area (Fig. 12). The predominant structural features in the vicinity of the study area are broad, southeast-plunging folds such as the Jacalitos Dome, and Coalinga and Kettleman Hills anticlines (Fig. 11). There is little faulting in the vicinity of the study area and there were no faults recognized in the study area that cut the Domengine Formation. Paleocene rocks are absent in the Alcalde Hills. In this region and to the south, there was either pre-Eocene or early Eocene uplift. This resulted in the nondeposition or erosion of any Paleocene deposits. In the Alcalde Hills and Reef Ridge area the Cretaceous section was tilted, eroded, and unconformably overlain by the Eocene rocks of the Domengine and Avenal Formations (Kappeler 1984; Kappeler and others, 1984). The Domengine pinches out north of Los Gatos Creek and is absent for approximately 4 km (Figs. 1, 2). In this region, the lower middle Eocene Kreyenhagen Shale lies unconformably on the late Cretaceous Moreno Shale. The Domengine is absent due to erosion or nondeposition. In the northern portion of the study area (Big Blue Hills), late Paleocene and early Eocene rocks of the Lodo Formation and Eocene Yokut Sandstone crop out on the flanks of the Coalinga anticline. There was, therefore, a depositional basin present in this region during the late Paleocene and early 23 0 20 km 0 12 mi Coalinga xxxxx Study Area AAA Avenal Formation Anticline City 0.-o ~0 San Joaquin Guijarral Volley Hills Figure 11. Regional structure in the vic inity of the southern portion of the study area (Woodring and others, 1940; Kappeler, 1984}. HOLLISTER 5 0 10 20mi 0/ \------: "? : 5 0 10 20 30km ~ : (' - 0 36° 30' ~··Panache Creek ------c~ 't") /.- v.: 0-z 00 ..... , ~ 9c- . ' ~ ~ \~\ \~~ J'~~ \ -1>11" "' -' ~ r' ~" ' --- __) '\ 120° 45' 120°30' Figure 12. Regional structure in the northern portion of the study area. Outcrops of lower Tertiary sequences are indicated by the blackened areas (modified from Nilsen, 1981). N "" 25 Eocene. This basin did not experience continuous deposition. There was a short period of uplift and erosion resulting in the unconformity between the late Cretaceous Moreno Shale and the late Paleocene through early Eocene age Lodo Formation. A local unconformity is present at the base of the Domengine Formation at the contact with the Eocene Yokut Sandstone (Nilsen, 1 981) (Fig. 13). The post-Eocene structural history in the vicinity of the study area is similar in the north and south. Following deposition of the Domengine, there was a short period of erosion in the Salt Creek and Coalmine Canyon regions followed by quick subsidence throughout the area. This resulted in an unconformity between the shallow-marine Domengine deposits and the deep marine Kreyenhagen Shale. The evidence for such an unconformity includes the lack of transitional environments between these formations. Stratigraphy The Domengine Formation unconformably overlies the Joaquin Ridge member of the late Cretaceous Panoche Formation south of Los Gatos Creek (Figs. 2, 13). This member consists of massive, arkosic sandstone which was deposited by high-energy turbidites (Mansfield, 1972). The late Cretaceous Moreno Shale overlies the Panoche and underlies the Domengine north of Los Gatos Creek for approximately 5 km (Fig. 2). This formation consists of purplish-brown shale with interbedded sandstones. The Arroyo Hondo Shale member of the Lodo Formation Oate Paleocene-early Eocene in age) (Hornaday, 1974) underlies the Domengine to the north (Fig. 13) for a short distance and consists of deep-sea shale (Dibblee and Nilsen, 1974; Nilsen, -SOUTH NORTH- Cl> "'0 Cl> c -;::: ·;:;, 0 .: c c 0 "'c c Eo g. c.,. :;>.>1: ~0.311: u_,. ::> 0 NO - > CI>CI> -CI>""' -«> o"Ocp 0 0> Cl>> oc E <~> -CI> c Cl> .... c Q) qjc$ ·;::: ·- c o.c oo ::: § 0 .... o .... 0 ...... 0 ... oo .... 50 00 uu ou ou U)U uu <(:J:U WU) U ~ ...JU ...JU ______Temblor Formation (Miocene) 1 ------Kreyenhagen Shale Domengine and Yokut Domengine Sandstone undivided :~.:i~· r.:·~iTn:~~ O:.'I:""~··~~"~:;I;i.~:;.· ~ \ ' Yokut Sandstone .... ' \ ' .... \ ' ' ' Moreno Shale (Upper Cretaceous Cantua Sandstone 4000 ft. Member 1000 m 0 ft. Om Figure 13. North to south stratigraphic cross section along the south limb of the Vallecitos Syncline. Thicknesses south of Oil Canyon are approximated (modified from Nilsen, 1981). N C5"l 27 1981). The Yokut Sandstone is present below the Domengine north of Oil City. This unit consists of clean, friable, medium-grained, light gray sandstone which is commonly cross-bedded (White, 1940). It is coarser grained and lighter in color than the overlying Domengine Formation. The contact between the Domengine and Yokut Formations is recognized by a resistant fossiliferous pebble bed at the base of the Domengine. This contact is believed to be unconformable within the study area (Clark, 1926; White, 1940). Nilsen (1981) believes this interpretation is uncertain because "no visible discordance is discernible". If there is no unconformity, then the erosion represented by the laterally continuous basal pebble bed was probably of short duration. The basal pebble bed becomes discontinuous and consists of small pebble stringers north of Salt Creek. The Domengine and Yokut Formations eventually become undivided at East San Carlos Creek (approximately 16 km north of Salt Creek) (Fig. 13). The undivided strata continue northward into the Vallecitos area where they unconformably overlie the late Cretaceous Moreno and late Paleocene and early Eocene deposits of the Lodo Formation. In the Vallecitos area, these undivided strata were deposited in shallow marine environments such as prodeltaic, barrier-island, perideltaic, and shallow-marine deltaic regions (Nilsen, 1981). The Kreyenhagen Formation overlies the Domengine Formation within the study area. The Kreyenhagen Formation reaches a maximum thickness of 1,000 m and consists of diatomaceous shale, claystone, and a minor amount of sandstone (Dumoulin, 1984). The basal 30 m of the formation is known as the Canoas Siltstone member and consists of siliceous, calcareous, and 2 8 " . argillaceous shale with abundant foraminifera and siliceous microfossils (Cushman and Siegfus, 1939). At Reef Ridge, the Kreyenhagen contains fossil leaves and fish scales, and the lower Canoas Siltstone portion of the formation is noted for the abundance of the small mud pectinid known as Propeamussum interradiatum (Gabb) (Von Estroff, 1930). Living representatives of this macrofossil live at depths below 100 m in cool, normal-salinity water (Von Estroff, 1930). Von Estroff (1930), therefore concluded that the Kreyenhagen of Reef Ridge was deposited under marine conditions of normal salinity, at a depth which exceeded 100 m. The environment of deposition deepened toward the top of the Kreyenhagen Formation. Steinmeyer (1972) stated that the microfossils indicated a slope to basin-floor environment which had open sea connections. The Canoas Siltstone member overlies the Domengine throughout the study area and commonly contains glauconite near the base (Mallory, 1959). Microfossil data indicate that this member was deposited in similar deep-sea environments as the Canoas Siltstone of Reef Ridge (Mallory, 1959). Milam (1984) noted that the contact between the Domengine and Kreyenhagen Formations is time transgressive. He examined well data due east of the study area and discovered that within a distance of 50 km, the age of the contact ranges from late early/early medial Eocene to middle medial Eocene. Within the study area the Canoas siltstone contains Rhabdosphaera inflata, the calcareous nannoplankton species that is a zonal marker for the R. inflata subzone of Bukry (1973). This subzone is equivalent to early medial Eocene age (Milam, 1984). .. - LITHOSOMES AND DEPOSITIONAL ENVIRONMENTS INTRODUCTION The Domengine Formation consists predominantly of muddy sandstone and siltstone and contains over 30 species of marine molluscs. The formation contains abundant, secondary satin spar gypsum and reaches a maximum thickness of 65 m in Coalmine Canyon (Fig. 3). The name "Domijean" was used by Anderson (1905) (Fig. 14) for exposures of sandstone of the Domengine and Cantua Formations in the Oil City area. Anderson and Pack (1915) considered these rocks to be part of the "Tejon" Formation. The sequence of rocks currently referred to as the Domengine Formation was defined by Clark in 1926. Clark did not formally designate a type section, but he based his description upon exposures in the Domengine Creek area (Fig. 3). The nomenclatural history of the Domengine and associated formations is shown in Figure 14. Six stratigraphic sections were measured. These sections include Coalmine Canyon, Oil City, Salt Creek, Section A, Section B, and the type area in Domengine Creek (Fig. 3). Fifteen lithosomes were designated and interpreted, the distribution of these units is shown on figure 15. The names of the lithosomes and the environment which they represent is shown on Table 6. The lithosomes found in Coalmine Canyon differ significantly from those found throughout the other sections and are only found in Coalmine Canyon. Coal seams within the Domengine are common in Coalmine Canyon, but are restricted to the Alcalde Hills (Fig. 15). The San Joaquin Mining 29 t WHITE (1940) ::E (/) ARNOLD and ANDERSON w w ANDERSON CLARK VOKES DIBBLEE and THIS PAPER 1- a: ANDERSON and PACK Nl LSEN ( 1974) (/) w >- (/) (1905, 1908) (1926) (1939) 1986 (/) (1910) (1915) HORNADAY (1974) NILSEN (1981) MONTEREY Diatomaceous ~~REYENHAGEJ KREYENHAGEN KREYENHAGEN KREYENHAGEN ~ (Oligocene) KREYENHAGEN w lJ... Shale z DOMIJEAN w z TEJON DOMENGINE DOMENGINE (.) 0 Sandstone DOMENGINE DOMENGINE >- 0 J a: w KREYENHAGEN w <{ 1- YOKUT YOKUT MARTINEZ j: AVENAL Clay Shale a: w w 1- z ARROYO w MEGA NOS (.) LODO LODO 0 HONDO w ....J <{ a. / / / a. (/) ::l ::l u~ 0 0 0 a: MORENO MORENO MORENO MORENO MORENO w a; KNOXVILLE- Figure 14. Nomenclatural history of the names and ages of the formations in the study area (modified from Anderson and Pack, 1915; and White, 1940). w 0 NORTH SOUTH Ql .>« m <( Ql -=~ >. ~ CI'QI c c ~c u .,c:::O> ... 0 ·- 0>. :;:: u- .!:!.... _cE eu 0 cO 0 0 lil Ql oU en 0 en i5 en u ..- --. -_, .= - -- . - . HIATUS Gray ~ Figure 15. North to south cross section showing the distribution of lithosomes in the Domengine Formation plotted versus time. Explanation for the symbols is shown on Figure 4. w 32 TABLE 6. LITHOSOMES WITHIN THE DOMENGINE FORMATION AND THE ASSOCIATED DEPOSffiONAL ENVIRONMENTS Lithesome Environment Coal poorly drained swamp Carbonaceous Mudstone poorly drained swamp (higher clastic influx) Claystone overbank flood deposits Pebble Conglomerate distributary channel Gray Sandy Mudstone subaerial levee (highly vegetated) Mudstone-Pod-Bearing Sandstone subaerial levee Ostrea-Bearing Sandstone interdistributary bay beach Coarse Sandstone storm deposit Fossiliferous Sandstone lower shoreface Fine Structureless Sandstone middle shoreface Conglomeratic Sandstone transgressive lag Fine Sandstone storm deposist Sandy Mudstone transition zone Glauconitic Sandstone lower shoreface -- 33 Company attempted to mine this coal in the 1800's by digging a mine in this canyon. The mine was abandoned, however, when the enterprise proved unprofitable (Arnold and Anderson, 191 0). A few of the environments distinguished within this report include middle and lower shoreface and transition zone deposits. As used in this report, the shoreface extends from the effective wave base to the mean low water level. The transition zone lies just below the shoreface and effective wave base. It consists of transitional sediment between shelf mud and coastal sand (Reineck and Singh, 1975). COAL Description Exposures of coal seams within the Domengine Formation occur in Coalmine Canyon and in an unnamed canyon approximately 3 km to the north (Fig. 3). Four coal seams occur in the Coalmine Canyon section. These seams are 10 to 15 m apart and interbedded with the Ostrea-bearing sandstone and carbonaceous mudstone lithosomes (Fig. 5A, 5B). The coal is grayish black (N2) and dark gray (N3) on a fresh surface and dark gray (N3) and moderate reddish brown (lOR 4/6) on a weathered surface. Portions of the lithesome have a splotchy appearance and are coated with sulphur. The lithesome is moderately well exposed and forms a nonresistant sloping surface between the overlying and underlying lithosomes (Fig. 16). The coal seams are tabular, are laterally continuous within the canyon, and average 35 em in thickness. They contain no visible internal structures or bedding. The unit is heavily fractured and has good fissility. The coal 34 Figure 16. Coal seam within the Coalmine Canyon section. Hammer is 33 em long. Photo was taken approximately 15 m above the base of the formation. 35 consists predominantly of lignite. It is moderatly indurated and has a sharp, regular basal contact. The lithosome has a sharp and irregular contact with the overlying Ostrea-bearing sandstone, but has a 25 em gradational contact with the overlying carbonaceous mudstone lithosome. Interpretation The coal was formed in a poorly drained swamp (Reineck and Singh, 1975; Blatt, 1982). Coal is especially characteristic of deltas (Selley, 1982) and is formed in nonmarine swamps. Swamp conditions promote the growth of vegetation (Coleman and others, 1964; Blatt, 1982) and peat is the most common type of marsh deposit (Kolb and Van Lopik, 1966). The swamp water is slightly acidic and the growth of vegetation far exceeds the clastic sedimentation rate (Pettijohn, 1975). To maintain a low sedimentation rate, the swamp must be protected from major inundations of the sea and river flood waters. The coal seams found in Coalmine Canyon were therefore formed behind a seaward barrier such as a beach or levee. Landward of the swamp, a lowland caught most of the fluvial sediment and allowed uninterrupted peat formation. The Coalmine Canyon region was slowly subsiding so that a continuous rise of the groundwater table allowed the formation of peat. CARBONACEOUS MUDSTONE Description The carbonaceous mudstone lithosome occurs in the middle portion of the Coalmine Canyon section interbedded with the coal and Ostrea-bearing 36 sandstone lithosomes (Fig. 5). The lithosome varies between yellowish gray (5Y 8/1 and 5Y 7/2), light olive gray (5Y 6/1), moderate red (5R 4/6), pale yellowish green (10 GY 7/2), and grayish yellow (5Y 8/4) on fresh and weathered surfaces. Sulphur coats many of the weathered surfaces. The weathered unit forms slope topography. The lithosome is tabular within the canyon and averages 10 m in thickness. The unit is predominantly structureless, however, it does contain carbonaceous material and coal pods which comprise 5 to 10% of the unit. The carbonaceous material occurs as small fragments which vary in size and are scattered throughout the lithosome. Coal occurs in irregular pods which lie predominantly parallel to bedding (Fig. 17). These pods average 15 em in width and 60 em in length. The coal is low-grade lignite and is usually coated with sulphur. The lithosome contains scattered spherical calcareous concretions. The unit consists of sandy mudstone: immature leucoxene-bearing arkose (CMC E, Table 1). It has a median grain size of medium silt, is very poorly sorted, strongly fine skewed, and platykurtic. The carbonaceous mudstone lithosome is moderately to poorly indurated and is in sharp basal contact with the Ostrea-bearing sandstone. The unit's basal contact with the coalli_thosome is gradational within approximately 25 em. The upper contact with the coal is sharp and regular. No macrofossils were found. Interpretation The carbonaceous mudstone lithosome was deposited in a poorly drained 37 Figure 17. Coal pods within the carbonaceous mudstone lithesome. Pods do not necessarily follow bedding. Hammer is 33 em long. Photo taken approximately 22 m above the base of the formation. 38 swamp on the upper delta plain. The environment of deposition was similar to that which formed the coal lithesome, however, the deposition of organic material was periodically interrupted by the deposition of fine clastics. The gradational basal contact of the lithesome with the coal seams indicates that the clastic influx slowly increased until it eventually exceeded the rate at which the vegetation was accumulating. Poorly drained swamps are predominant on the delta plain and commonly consist of sandy mudstone (Fisk and McFarlan, 1954). They contain black mud and a high percentage of carbonaceous material. Although occasional thin stringers of peat are present in the mud, the majority of structures are destroyed by bioturbation. The plant material is well preserved in the reducing swamp environment. The resulting swamp deposits, therefore, consist of a homogeneous mixture of sand, silt, clay, and plant remains (Fisk and McFarlan, 1954; Coleman and others, 1964; Kolb and VanLopik, 1966; Reineck and Singh, 197 5) much like the deposi sts of the carbonaceous mudstone lithesome. CLAYSTONE Description The claystone lithesome occurs in the lower half of the Coalmine Canyon section above the gray sandy mudstone lithesome and below the mudstone-pod-bearing sandstone. The unit consists entirely of claystone and is light gray (N7) on fresh surfaces and very light gray (N8) on weathered surfaces. The unit is poorly exposed and is slope forming. The claystone is approximately 2 m thick, however, due to the poor ..... - 39 quality of the exposure, the overall shape of the unit could not be determined. The unit is structureless and consists of pure claystone. Carbonaceous material is present and makes up less than 1% of the unit. The lithosome is poor to moderately indurated and has a sharp upper contact with the mudstone-pod-bearing sandstone. The lower contact with the gray sandy mudstone is gradational. No macrofossils were found. Interpretation The claystone lithosome was formed by overbank flooding upon the upper delta plain. Overbank flooding is a process which operates during a flood. The flood water spills over the channel banks as sheet flow. The fine grained suspended sediment is then deposited over the delta plain. Any coarser sediment is confined to the margins of the levee (Coleman, and others, 1964-; Elliott, 1974; Reading, 1978). Overbank flooding deposits, like that of the claystone lithosome, are associated with the coarser levee deposits and consist of fine silt and mud. The deposits are finely laminated, but they may become homogenized by bioturbation (Elliott, 1974-; Reading, 1978). The flooding can produce deposits of siltstone or as fine as claystone (Elliott, 1974-). The low percentage of organic material within the lithosome indicates that the unit was deposited in an area that had less vegetation than the swamps which formed the coal and carbonaceous mudstone lithosomes. The claystone was formed by overbank flooding, and therefore must have been deposited closer to the distributary channel of the delta than the swamp deposits. 40 PEBBLE CONGLOMERATE Description The pebble conglomerate lithesome crops out in Coalmine Canyon at the base of the Domengine Formation (Fig. 5). The lithesome consists of pebble conglomerate (20%) and medium-grained sandstone (80%). The unit is very pale orange (lOYR 8/2) on fresh and weathered surfaces. The lithesome is well exposed and is slope forming. It is approximately 3 m thick in Coalmine Canyon but varies laterally in its thickness. The unit contains three to four pebble conglomerate beds which range from 12 to 20 em in thickness and are laterally continuous within 4 m. No imbrication, grading, or stratification of the clasts was observed. The base of the conglomerate lenses show scour and fill structures. The pebble conglomerate grades into medium-grained sandstone, forming a slight fining upward cycle. There are several of these cycles within the lithesome and the cycles average approximately 25 em in thickness. The medium-grained sandstone portion of the lithesome contains a variety of sedimentary structures including parallel laminations and low-angle cross bedding. The parallel laminations follow bedding. Some of the laminations are lined with carbonaceous material and average 2 mm in thickness and 25 em in length. The cross beds range from 6 to 25 em in height. The largest cross beds are outlined by mudstone rip-up clasts along the laminations. These rip-ups average 1 em in diameter. The sandstone also contains bits of coal averaging 3 mm in diameter. The pebble conglomerate has a median grain size of very coarse sand, and is very poorly sorted, fine skewed, and platykurtic. The majority of ...... -- 41 clasts are poorly sorted and matrix supported (70%) in coarse-grained sandstone. The clasts constitute 10% of the lithesome and range in size from granule to pebble, averaging pebble. They are equant, subrounded, and vary in composition. The majority of the clasts consist of black chert and sandstone (Sample CMC C; Table 3). These black chert clasts tend to be the largest. The shale clasts include Panoche Formation siltstone fragments that occur approximately 5 m below the basal contact. The sandstone portion of the lithesome varies between fine- and medium-grained sandstone and is poorly sorted. The lithesome is poorly indurated and is in gradational contact with the sandy mudstone lithesome. The unit unconformably overlies the Late Cretaceous Panoche Formation. No macrofossils or signs of bioturbation were found. Interpretation The pebble conglomerate lithesome is similar to modern distributary channel deposits described by Reineck and Singh (1975). These deposits have erosive bases lined with a basal channel lag (Reading, 1978) and contain clay fragments. The most common sedimentary structures are cross bedding and scour-and-fill structures (Coleman and others, 196~; Reineck and Singh, 1975; Davis, 1978; Coleman, 1982). Carbonaceous material occurs along parallel laminations. A fining-upward sequence is characteristic of the sandy units (Coleman, 1982). A predominance of coarse material interbedded with fine sandstone and clay is characteristic of distributary channel deposits. Clay layers are not always preserved and may be eroded and incorporated within the deposit as rip-up clasts (Coleman and others, 1964; il ' 42 Reineck and Singh, 1975; Coleman, 1982). These same features are found in the pebble conglomerate lithosome. GRAY SANDY MUDSTONE Description The gray sandy mudstone lithosome crops out at a single location near the base of the Domengine Formation in the Coalmine Canyon section. The unit is light gray (N8) on fresh surfaces and weathers to small light gray (N7) mudstone balls which cover approximately 80% of the lithosome. The unit weathers to form steep-slope topography. The lithosome is tabular within the canyon and is approximately 8 m thick. It contains approximately 1% carbonized bits which occur along parallel and wavy laminations. These laminations average 3 mm in width and vary in length. They are the only structures within the lithosome. The lithosome consists of sandy mudstone: immature subarkose. The sand grains consist predominantly of quartz, with minor amounts of potassium and plagioclase feldspar (CMC D, Table 1). The unit is poorly to very poorly sorted and varies in composition between sandy mudstone and muddy sandstone. The gray sandy mudstone lithosome is moderately indurated and has gradational contacts with the underlying pebble conglomerate lithosome and overlying claystone lithosome. The unit is unfossiliferous. Interpretation The gray sandy mudstone lithosome represents a transition in grain size 43 from the underlying distributary channel (pebble conglomerate) deposits to the overlying overbank flood (claystone) deposits. The contacts with both the pebble conglomerate and the claystone lithosomes are gradational. The gray sandy mudstone lithesome represents subaerial levee deposits of a distributary channel. Levee deposits must be present stratigraphically between channel and overbank flood deposits (Reading, 1978). Subaerial levee deposits consist of poorly sorted sand and silt. They generally contain abundant sedimentary structures such as climbing ripples, parallel and wavy laminations, and cross bedding (Coleman and others, 1964; Reineck and Singh, 1975; Van Heerden, 1982). Intense burrowing by plants and animals, however, may obscure these structures (Coleman and others, 1964), as in the gray sandy mudstone lithesome. Plant remains and organic matter are abundant and may occur along laminations and bedding (Kolb and Van Lopik, 1954; Coleman and others, 1964). Structureless deposits are most commonly formed in areas where the levee was covered by vegetation. MUDSTONE-POD-BEARING SANDSTONE Description The mudstone-pod-bearing sandstone lithesome occurs in the lower half of the Coalmine Canyon section in only one location (Fig. 5A). The lithesome consists of sandstone (95 to 98%) and mudstone (2 to 5%). It is very pale orange (IOYR 8/2) and light brown (5YR 5/6) on fresh and weathered surfaces. It is well exposed in areas and weathers to form slope topography. It is tabular within the canyon and averages between 1 and 2m in thickness. 44 Sedimentary structures within the lithesome include parallel and wavy laminations and small scale tabular cross bedding. These cross beds are low angle and approximately 3 em in height. The laminations range from 2 to 7 mm in thickness, averaging 4 mm. Mudstone occurs within the lithesome lining parallel and wavy laminations and in pods and lenses. These pods and lenses range from 1 to 6 em in length and from 0.5 to 4 em in width. Carbonaceous material and wood fragments comprise 1 to 2% of the lithesome. This material occurs along wavy and parallel laminations which range from 1 to 3 em in thickness and vary in length. Small bits of carbonaceous material are scattered throughout the sandstone and range from 0.5 to 5 em in diameter, averaging 1.5 em. The sandstone consists of moderately-sorted, medium- to fine-grained sandstone. The grains are subrounded and have moderate sphericity. In hand sample they appear to have moderate to poor compositional maturity. The unit is poorly indurated and uncemented. It sharply overlies the underlying claystone and overlying coal lithesome. No macrofossils were found within the lithesome. Interpretation The mudstone-pod-bearing sandstone lithesome is similar to the modern subaerial levee deposits described by Reineck and Singh (1975) and Van Heerden, (1982). The environment of deposition was similar to that which formed the gray sandy mudstone lithesome, however, there was very little vegetation on the levee during the deposition of the mudstone-pod-bearing 45 sandstone. This lack of vegetation resulted in the preservation of the characteristic structures and features of the subaerial levee environment. These structures include small-scale cross bedding and parallel and wavy laminations (Coleman and others, 1964; Reineck and Singh, 1975; Van Heerden, 1982; Coleman, 1982). Wavy laminations are abundant and are commonly produced by interference from grass roots or other organic material (Coleman and others, 1964; Coleman, 1982). Plant debris and carbonaceous material are deposited in the sediment along laminations and as individual particles (Coleman and others, 1964; Reineck and Singh, 1975). Mudstone can be very abundant (Reineck and Singh, 1975; Coleman, 1982). OSTREA-BEARING SANDSTONE Descriptioo The Ostrea-bearing sandstone lithosome occurs in the upper half of the Coalmine Canyon section. It consists of sandstone (95%) and fossiliferous lenses (5%). The unit is interbedded with the coal and carbonaceous mudstone lithosomes (Fig. 5B). The lithosome has a homogeneous to splotchy colored appearance. It weathers to grayish yellow (5Y 8/4), light gray (N7), dark yellowish orange (lOYR 6/6), and light greenish gray (5GY 8/1). It is light gray (N7) and yellowish gray (5Y 8/ 1) on fresh surfaces. The lithosome weathers to slope topography. The Ostrea-bearing sandstone is tabular in shape and averages approximately 5 to 7 m in thickness. The lithosome comprises nearly a third (23.5 m) of the Domengine Formation in Coalmine Canyon. Approximately 75% of the lithosome is structureless. The unit does 46 contain sedimentary structures such as parallel and wavy laminations, and low-angle cross bedding. The cross beds average 6 em in height and are tabular in shape. Carbonaceous material occurs along many of the parallel and very laminations. These laminations average 2 mm in width and vary in length. The carbonaceous material also occurs in small bits scattered throughout the sandstone which range from 1 mm to 2 em in diameter. Rounded carbonized wood fragments reach lengths of 3 em and widths of 1 em. Spherical calcareous concretions occur scattered throughout the upper portion of the lithosome (Fig. 5). The sandstone consists of moderately sorted fine sandstone: calcitic submature chert-bearing arkose (CMC F, Table 1). Sieve analysis reveals that the lithosome has median grain size of fine sand, is very poorly sorted, strongly fine skewed, and very leptokurtic. The lithosome is poorly indurated and uncemented. It is in sharp contact with the coal, carbonaceous mudstone, and coarse sandstone lithosomes (Fig. 5). The characteristic feature of this lithosome is the presence of fossiliferous lenses" These lenses contain Ostrea idriaensis, Selena sp., and other molluscs (Localities 866, 867, 868, Table 4). The majority of oysters are disarticulated and well preserved. However, a few articulated Ostrea and Selena were found. Vokes (1939) lists a wide assortment of species which are from the Coalmine Canyon area. His collection locality descriptions are vague, however, based on their approximate location and faunal content, some of these localities appear to be from the Ostrea-bearing sandstone lithosome. For a detailed listing of this fauna, see Vokes (1940, Table 3). 47 The fossiliferous lenses generally occur directly over coal seams and are 10 to 15 em thick. They consist of approximately 60% fossil material and 40% sandstone matrix. The sandstone matrix is of the same composition as the rest of the lithesome. The contacts of the fossiliferous lenses are gradational and no erosional surfaces are present. The lenses lie parallel to bedding in many areas, but one observed lens cuts across bedding at an angle of approximately 25 degrees. Burrows occur in the lithesome near the top of the formation. They are unlined and approximately 1 em wide and 2 em in length. They are predominantly vertical and bifurcate near the top of the burrow. Some are filled with mudstone. Ophiomorpha burrows also occur in the unit and average 1.5 em in width and 6 em in length and are predominantly vertical. Interpretation The Ostrea-bearing sandstone lithesome was deposited on the sandy beach of the interdistributary bay. Interdistributary bay deposits are commonly found interbedded with marsh and swamp deposits (Reineck and Singh, 1975). These bays contain brackish to marine water and rarely exceed 1 to 8 min depth, averaging 4 m (Coleman and Prior, 1982). The margins of the interdistributary bay are commonly lined with sandy beaches. These beaches often contain oyster fragments, small-scale cross bedding, and organic debris and clay laminations (Kolb and Van Lopik, 1966; Coleman, 1982). They typically consist of well sorted, fine- to very-fine grained sandstone (Kolb and Van Lopik, 1966). These beaches form on a low energy coastline. They contain many of the sedimentary structures associated with typical foreshore and shoreface deposits, including parallel 48 and cross laminations, and they are bioturbated (Reineck and Singh, 1975). The Ostrea-bearing sandstone lithesome contains some of these structures although they are relatively rare because of the low-energy environment. Therefore, the Ostrea-bearing sandstone lithesome was deposited along the shore of an interdistributary bay. The region may have subsided continuously, however, the area was occasionally built up enough by the influx of sediment to allow the formation of a heavily vegetated swamp. This formed the alternating sequence of coal and the Ostrea-bearing sandstone. The lenses of Ostrea were periodically deposited on the beach, possibly during moderate storm activity. These shells collected on the backshore, up against the marsh areas, forming the Ostrea lenses which directly overlie the coal seams. Such concentrated areas of shell material are commonly found on the backshore (Kolb and VanLopik, 1966; Reineck and Singh, 1975; Reading, 1978). The faunal assemblage found within the Ostrea-bearing sandstone is indicative of very shallow, marine to brackish water (Vokes, 1940; Givens and Kennedy, 1976; Lohmar and others, 1979). Vokes (1940) stated that the fauna of the Domengine Formation in Coalmine Canyon lived in water as shallow as 4 m or less. The presence of articulated Ostrea and Solena indicate that the organisms had been transported only a short distance, possibly while they· were still alive. Ostrea prefer shallow, protected, low-energy environments such as bays and lagoons (Lohmar and other, 1979). Therefore, a large Ostrea community was present within the interdistributary bay, only a short distance from the sandy beach where the lithesome was deposited. 49 The Ostrea lenses contain both brackish and marine water fauna. Ostrea can endure broad salinity fluctuations (Lohmar and others, 1979), however Nerita, Potamides, and Loxotrema prefer brackish water. The unit also contains fauna such as Nemocarduim and Crommium which live in normal salinity water (Givens and Kennedy, 1976). Since both brackish and normal salinity water environments occur in such close proximity to each other along a delta, this mixing of fauna would be expected for a storm deposit. COARSE SANDSTONE Description The coarse sandstone lithesome occurs at the top of the Domengine Formation in Coalmine Canyon. It weathers to a light olive gray (5Y 6/1) color and is yellowish gray (5Y 7/2) on fresh surfaces. The unit is very well exposed and forms a cliff. It is tabular and approximately 3m thick. The lithesome contains two to three fossiliferous lenses within the bed. These lenses are 30 to 50 em thick and continuous within 2 to 4 m. The matrix of these lenses is the same composition as the rest of the unit and consists of sandy conglomerate: calcitic submature chert-bearing arkose (CMC G, Table 1). It conta1ns grains ranging in size from very fine sand to granule. It has an average grain size of coarse sand, is poorly sorted, fine skewed, and very leptokurtic. The coarse sandstone lithesome is very well indurated due to the high degree of calcite cementation. It is in sharp contact with the underlying so Ostrea-bearing sandstone lithosome and overlying interbedded sandstone and siltstone lithosome. The fossiliferous lenses contain internal molds of bivalves such as Spisula sp., as well as the body fossils of gastropods such as Crommium andersoni and Odostomia griswoldensis (Table 4). The bivalve molds are the most abundant fossil and comprise approximately 20% of these lenses. All the fossils are abraided and poorly preserved. The bivalves are disarticulated and the entire assemblage is randomly oriented. Interpretation The coarse sandstone lithosome is a storm lag which possibly was deposited on the shoreface of the sand beach along the interdistributary bay. The lithosome lies above the beach deposits of the Ostrea-bearing sandstone. Therefore, in a transgressive sequence, this lithosome most likely represents interdistributary bay or beach deposits. The coarse grain size of this unit is anomalous to this portion of the delta, however. The marine fossils in the coarse sandstone lithosome have been abraided and have undergone significant transport. The coarse grain size indicates deposition during heightened energy levels. The poor sorting and structureless nature of the unit is indicative of rapid deposition (Reineck and Singh, 1975). The lithosome may be deposits that were held in suspension by storm induced currents. "Storm lags" characteristically contain a high concentration of shell material and have a larger average grain size than the surrounding units. They range from 3 to 400 em in thickness and have a basal contact which is sharp and often erosive (Brenner and Davies, 1973; Kumar and Sanders, 1976). 51 Coarse-grained storm deposits commonly occur on the shoreface (Reineck and Singh, 1975; Kumar and Sanders, 1976; Reading, 1978). FOSSD..IFEROUS SANDSTONE Description The fossiliferous sandstone lithosome outcrops in all sections except Coalmine Canyon and Salt Creek (Fig. 15). It occurs with the conglomeratic sandstone and sandy mudstone lithosomes and consists of muddy sandstone (96%), fossiliferous material (3%), and organic material. (1%). It weathers to yellowish gray (5Y 8/ 1), grayish orange (1 OYR 7 /4), and dark yellowish brown (lOYR 4/2). On fresh surfaces it is yellowish brown (lOYR 4/2), very pale orange (1 OYR 8/2), and yellowish gray (5Y 8/ 1). The color distribution is splotchy (Fig. 18). The unit weathers to slope topography and exposures are generally poor due to extensive weathering and grass cover. The lithosome is tabular and ranges from 4 to 23 m in thickness. It is predominantly structureless (90 to 100% bioturbated) (Fig. 19), however individual burrows can be found. These unlined burrows are vertical and bifurcate near the top. Their average diameter is 8 mm. Solenid burrows are also present and average 1 em in width and 4 em in length. Rounded, oxidized wood fragments are scattered throughout the unit and range from 4 to 30 mm in length. Calcareous concretions also are present in this unit and average 25 em in thickness and 1 min length. The lithosome consists of muddy sandstone: immature glauconite-, biotite-, and limonite-bearing arkose (Table 1). It has a median grain size of medium to coarse silt, is moderately to poorly sorted, fine skewed, and is 52 Figure is. Fossiliferous sandstone lith esome in the Oil City section. A fine sand stone lithesome bed is near the top of the photo. Hammer is 33 em long. Photo taken near the base of the formation. -- 53 Figure 19. Mottled appearance of the fossiliferous sandstone lithosome in the Oil City sectio~. Hammer is 33 em long. @ • 54 mesokurtic to leptokurtic. The lithosome contains local accumulations of glauconite. The relative abundance of this mineral ranges from 0 to 5% (Table 1) and varies throughout the unit due to mottling. The lithosome is moderately to poorly indurated and poorly cemented. The basal contact is gradational within 25 to 50 em with the conglomeratic sandstone lithosome. It has a sharp upper contact with the fine sandstone lithosome and a gradational upper contact (within 20 to 50 em) with the sandy mudstone lithosome. The fossiliferous sandstone lithosome contains a wide assortment of fossiliferous material including fish scales, plant fragments, foraminifera (Table 5), and macrofossils (Table 4). The macrofossils include bivalves, gastropods, scaphopods, and echinoderms. These fossils occur predominantly within concretionary lenses. The macrofossils of this lithosome are moderately preserved. Fine nodes and ribs have been preserved on several of the specimens and a growth series of Turritella andersoni lawsoni was found. These Turritella range from 2 to 5 em in length. The molluscs characteristically found in this lithosome include Turritella andersoni lawsoni, Turritella bulwaldana, Turritella uvasana aedificata, Nemocardium linteum, Solena and several others listed on Table 4. Articulated bivalves were found in the Domengine Creek section (locality 862, Table 4) and include 2 specimens of Solena and one specimen of Venericardia (Pacificor) hornii calafia?. The lithosome contains over 20 species of foraminifera (Table 5). The most common genera include Anomalina, Cibicides, Elphidium, Nodogenerina, Robulus, and Tritaxia. The vast majority of the fauna is from the Rotaliina 55 suborder (Fig. 20). Planktonic foraminifera represent less than 10% of the fossil assemblage. The ostracods present are primarily ornamented (Table 5). Portions of the lithesome which contain high percentages of organic material have undergone secondary alteration. These areas have an irregular splotchy appearance. These splotches are pale yellowish green (5GY 7/4) and are surrou~ded by pale reddish brown (lOR 5/4) sandstone. Interpretation The fossiliferous sandstone lithesome was deposited on the lower shoreface of a low-energy coastline. This interpretation is based upon the fossils, the grain size, and the high degree of bioturbation present in the unit. Shoreface deposits usually contain many sedimentary structures, but a majority of these structures are subsequently destroyed by biogenic activity, as in the case of the fossiliferous sandstone lithesome. The degree of bioturbation is dependent upon the wave energy of the coastline. A river dominated delta environment in the vicinity of Coalmine Canyon is evidence that the Eocene coastline was a relatively low-energy environment. Low energy coastlines allow the large population of bioturbating organisms to homogenize the sediment thus forming deposits consisting of poorly sorted, structureless, fine-grained sandstone (Howard and Reineck, 1972; Reineck, 1975; Reading, 1978). With such a high degree of bioturbation, there are few individual burrows remaining (Howard and Reineck, 1972). Lower shoreface deposits can be muddy if silt and clay are available (Howard and Reineck, 1972; Howard, 1972). They can contain shell layers and a high percentage of organic detritus (Howard, 1971; Howard and Reineck, 56 Number of individuals ® Sandy Mudstone ® Fossiliferous Sandstone Figure 20. Alpha index plot of the foraminifera of the fossiliferous sandstone and sandy mudstone lithosomes (from Murray, 19 7 3) . 57 1972; Reineck and Singh, 1975), much like the fossiliferous sandstone lithesome. The subsea depth at which the lower shoreface occurs is dependent upon the energy level of the coastline. The lower the energy of the coast, the shallower the depth limits of the shoreface. The lower limit of the shoreface is generally 10m, however this limit can reach depths of 20m (Howard and Reineck, 1972; Reineck and Singh, 1975). The formation of glauconite requires 1) slightly reducing conditions, 2) a slight agitation of the water, 3) a slow sedimentation rate, and 4) depths ranging from 18 to 730 m (Pettijohn, 1975; Selley, 1982). The relatively low percentage of glauconite indicates that the conditions present during the formation of this lithesome were only marginal for the formation of the mineral. The macrofossils found within the lithesome are indicative of shallow marine conditions. The majority of macrofossils appear to have been transported only short distances, however, the articulated Selena and Venericardia were most likely in situ. These Venericardia, such as V. (Pacificor) hornii calafia?, are often found with Turritella and prefer nearshore, shallow-water environments. Turritella prefer a fine-grained substrate, a low amOtmt of turbulence, and waters shallower than 50 m (Saul, 1983). Selena is most frequently found in nearshore areas. The genera Calyptraea, Nemocardium, Glycymeris, and Pitar also prefer shallow water and are most frequently reported at depths shallower than 50 m (Squires, 1984). The microfossils present within this lithesome confirm the environmental conditions indicated by the macrofossils. The number of 58 species was plotted against the number of individuals in order to determine the alpha index of the sample. This index helps determine whether the foraminifera are primarily from hypersaline or normal saline waters (Fig. 20). This lithesome has an average alpha index of six, which indicates that it was probably deposited in a normal saline shelf environment (Murray, 1973). Ornamented ostracods also prefer normal salinity water (Alan Hershey, pers. communication). The low percentage of planktonic forams indicates a shallow shelf environment. The genera most abundant in this lithesome are commonly found in normal marine waters of the inner shelf at depths of 0 to 50 m (Murray, 1973). FINE STRUCTURELESS SANDSTONE Description The fine structureless sandstone lithesome occurs in the Salt Creek section interbedded with the conglomeratic sandstone lithesome. It comprises 95% of this section (Fig. 1 0). The sandstone is light gray (N2) and iight brown (SY 5/6) on fresh surfaces and weathers to yellowish gray (5Y 8/1) and light brown (5YR 5/6). It is well exposed and forms cliff topography. The lithesome is tabular and has an approximate thickness of 38 m. Bedding is present in some areas and averages approximately 40 em in thickness. The lithesome, however, is predominantly structureless and 70 to 90% bioturbated. It is locally parallel laminated and cross bedded. The parallel laminations range from 1 to 15 mm in thickness, averaging 8 mm. The trough cross bedding is very rare and each set averages 2 em in thickness and 8 em in length. Bioturbation was recognized by a mottled appearance 59 and the presence of patches of medium- and coarse-grained sandstone within the unit. The presence of secondary limonite stains outline remnant burrows. Burrow traces are present and preserved Ophiomorpha burrows were found. These burrows average 1 em in diameter and are of varying lengths. Solitary spheroidal concretions of various sizes are scattered throughout the lithesome. The lithesome consists of moderately-sorted, fine-grained sandstone. The grains are subangular and have moderate sphericity. The compositional maturity is moderate. The unit contains a large amount of silt and clay, is moderately to well indurated, and is in gradational contact (within 20 to 40 em) with the conglomeratic sandstone lithesome. The upper contact with the Kreyenhagen Formation is covered. The lithesome is unfossiliferous. Interpretation The fine structureless sandstone lithesome is interpreted to have formed in a middle shoreface environment. The amount of bioturbation decreases and the sediment grain size increases landward aiong the shoreface. The decrease in bioturbation leads to an increase in preserved primary sedimentary structures (Howard, 1971; Howard and Reineck, 1972; Reineck and Singh, 1975; Coleman, 1982). The fine structureless sandstone lithesome is slightly coarser grained, contains more sedimentary structures, and is slightly less bioturbated than the lower shoreface deposits of the fossiliferous sandstone lithesome. Therefore, this lithesome was formed landward of the lower shoreface deposits of the fossiliferous sandstone lithesome. @ • 60 Ophiomorpha traces are a common feature on the shoreface (Howard, 1971; Howard and Reineck, 1972). Parallel laminations, like those found in the fine structureless sandstone lithesome, are the most common sedimentary structure found on the middle shoreface. Cross bedding does occur but is rare (Reineck and Singh, 1975; Reading, 1978). CONGLOMERATIC SANDSTONE Description The conglomeratic sandstone lithesome is traceable in outcrop from 3 km north of Los Gatos Creek to the northern portion of the study area. It lies at the base of the formation, unconformably overlying the Yokut Formation. The unit consists of 65% sandstone matrix, 35% clasts, and 5% fossils. The lithesome weathers to dark yellowish orange (1 OYR 8/2) and light olive gray (5Y 6/1). On fresh surfaces it is very light gray (N8) and grayish orange (1 OYR 7/4). It is tabular in shape and ranges from 2 to 50 em in thickness, averaging 25 em. The lithesome is predominantly structureless but burrows occur at the upper contact where there is a gradation into the fossiliferous sandstone and fine structureless sandstone lithosomes (Fig. 21). The burrows are vertical and horizontal, with vertical predominant. They range from 1 to 3 em in width and average 8 em in length. In the Salt Creek section, the lithesome also occurs within the middle of the Domengine in the fine structureless sandstone lithesome. These exposures show excellent bedding and in some areas consist of a single, parallel bedded layer of pebbles (Fig. 22). In one location, the unit has an erosional base and forms a channel within the fine structureless sandstone. 61 ~1 • Figure 21. Conglomeratic sandstone lithesome in the Domengine Creek section. Knife is 9 em long. Photo taken at the base of the formation. .. .. ~·~~~~: \;:.:>:~·.~>i·/~··r :/~.;.~:>.-~:~;>~·-.\~~;:::.~:t.~~.:-··.~-~i:...... .· :· ... : .. : 0.. . . A 8 Figure 22. The conglomeratic sandstone lithesome of Salt Creek. The lithesome is interbedded with the fine structureless sandstone lithesome and shows; A) channel structure, and B) normal parallel bedding. Location of these structures is shown on Figure 10. 62 This channel is 1 m wide and 30 em deep • The base of the channel is outlined with a 10 em thick layer of matrix supported pebbles. The channel is overlain by alternating layers of sandstone and parallel-bedded gravel (Fig. 22). The lithesome consists of conglomeratic sandstone: calcitic submature hematite-, limonite-, and chert-bearing lithic arkose (DC 2, Table 1). It has a median grain size of very fine- to medium-grained sand, is very poorly sorted, strongly fine skewed, and leptokurtic. The sandstone matrix is fine to medium grained and poorly sorted. The clasts are subrounded and matrix supported. They consist almost exclusively of black and gray chert, which are predominantly the largest grains (Table 3). The size of the clasts ranges from 1 to 37 mm in diameter, averaging 7 mm (small pebble). The clasts at the base of the formation in the Salt Creek section are much larger than those found in the sections to the south. The lithesome within the middle of the Salt Creek section contains clasts which are much smaller, ranging from 5 to 15 mm in diameter, averaging 10 mm. The lithesome is very well indurated and forms a distinctive ridge at the base of the Domengine Formation. This induration is due to extensive calcite cementation. The basal contact of the lithesome. is erosional and irregular south of Domengine Creek. In this area the contact is very sharp and cuts off burrow traces within the underlying Yokut sandstone. At Domengine Creek the contact is diffuse, northward to Salt Creek it becomes progressively more gradational with the Yokut. However, in portions of Salt Creek the contact is erosional. In Salt Creek the clasts are substancially larger than the clasts 63 found to the south. The lithosome's upper contact is gradational within 25 to 50 em with the fossiliferous sandstone and fine structureless sandstone lithosomes. The fossils found within the lithosome are listed in Table 4. It characteristically contains the following bivalves: Crassatella uvasana, Glycymeris sagittata, Macrocallista (Costacallista) domenginica, Nemocardium linteum, Pitar (Calpitaria) campi, and Venericardia (Glyptoactis) domenginica (localities 860, 863, 864; Table 4). The bivalves are poorly preserved, broken, abraided, and disarticulated. The exposures of this lithosome in the Salt Creek section are unfossiliferous. Interpretation The conglomeratic sandstone lithosome is a transgressive lag. Transgressive lags are formed by the shoreline advance along an actively subsiding basin (Swift, 1968, 1975). Clifton (1981) described such deposits as laterally continuous conglomerates consisting of pebbles, granules, and fossil material (Swift, 1968, 1975). The lags typically lie upon planar erosion surfaces and are less than 30 em thick (Clifton, 1981), similar to those seen in the Domengine Formation. The transgressive lag is associated with the lower shoreface deposits of· the fossiliferous sandstone lithosome in the Domengine Creek section, sections A and B, and the Oil City section (Figs. 6, 7, 8, and 9). The lag therefore, was deposited in the lower shoreface environment. In Salt Creek, the conglomeratic sandstone was deposited on the middle shoreface along 64 with the associated deposits of the fine structureless sandstone lithosome (Fig. 10). The occurrences of the conglomeratic sandstone higher in the Salt Creek section were formed by storm activity on the middle shoreface. During a storm, the high-energy river water brings coarser material to the beach region. The coarse material rolls around on the shoreface during the maximum storm intensity, and as the energy level decreases, it is deposited. Pebbles deposited by waves occur along laterally continuous discrete beds (Clifton, 1973), similar to the outcrops in the Salt Creek area. FINE SANDSTONE Description The fine sandstone lithosome occurs in the Domengine Creek section, sections A and B, and the Oil City section. It is interbedded with the fossiliferous sandstone and sandy mudstone lithosomes and is grayish orange (lOYR 7 /4), very light gray (N8), and dark yellowish orange (lOYR 6/6) on fresh and weathered surfaces. The unit is usually well to moderately exposed and forms a small ridge. It is tabular in shape, laterally continuous, and ranges from 5 to 50 em in thickness. The lithosome is pregominantly structureless, however, burrows do occur near the top of the unit. The burrows average 5 to 7 mm in width and 3 em height. They are predominantly vertical and bifurcate near the top of the burrow. Ophiomorpha burrows are also present and are 1 em wide and of varying lengths. 65 The tmit consists of well sorted fine sandstone: calcitic mature arkose. Sieve analysis reveals that it has a median grain size of coarse silt and very fine sand, ranges from moderate to poorly sorted, is fine skewed to nearly symmetrical, and is leptokurtic to platykurtic. The lithosome contains floating granules and small pebbles in the Domengine Creek section. The subrotmded clasts range from 2 to 6 mm in diameter and comprise less than 1/2% of the sandstone. They are similar in composition to the pebbles fotmd in the conglomeratic sandstone lithosome (Table 3). The lithosome is moderately to poorly indurated and in some areas is uncemented. The unit has sharp, irregular basal contacts and sharp upper contacts. The lithosome is tmfossiliferous. In Domengine Creek the lowest occurrence (Fig. 9) of the lithosome has been diagenetically altered. This sandstone bed is approximately 7 em thick and gypsum cemented (Table 1). The bed is dark yellowish orange (lOYR 6/6) and moderate red (5R 4/6) at the base. The sandstone grades through shades of brown and black and is light gray (N7) at the top. Dark gray (N3) streaks cut across the light gray portion of the sandstone at angles greater than 60 degrees indicating a diagenetic origin of the colors of this bed. Interpretation The fine sandstone lithosome was deposited during storm activity on the lower shoreface and within the transition zone. Storm deposits occur on shelves, as well as the shoreface. The sand beds are interbedded with silt and clay of the shelf and are very common within transition zone deposits (like those of the sandy mudstone lithosome). These deposits pass upward into 66 amalgamated layers of the parallel laminated and structureless beds of the upper shoreface (Reineck and Singh, 1975; Kumar and Sanders, 1976). According to Goldring and Bridges (1973), storm deposits, also known as sheet sandstones, are formed by storm waves, tsunamis, and ebb tidal currents. Their description of these storm deposits closely matches that of the fine sandstone lithesome. They state that these sheet sandstones consist of laterally continuous, fine-grained, well-sorted sandstone. The beds range from 5 to 70 em in thickness and have gently undulating erosional bases. Their upper contacts can be sharp or gradational. The sand sheets have parallel laminations and are often bioturbated at the top, however bioturbation may obscure any sedimentary structures present. The presence of floating pebbles and granules within the fine sandstone lithesome is indicative of quick deposition, the type of deposition which would occur during a storm (Reineck and Singh, 1975). SANDY MUDSTONE Description The sandy mudstone lithesome occurs in the upper portion of the Domengine Formation in the Domengine Creek section, in sections A and B, and in the Oil City section. The majority of the lithesome weathers to pale brown (5YR 5/2), however, portions of the unit are olive gray (5Y 4/1). It is olive gray (5Y 4/1), light brown (5YR 5/6), and medium light gray (N6) on fresh surfaces. The color distribution is homogeneous and the lithesome weathers forming slope topography. 67 The unit is tabular and ranges in thickness from 3 to 10.5 m. It is structureless (90 to 100% bioturbated) and individual burrows are very rare. The lithosome consists of sandy mudstone: immature chlorite-, foraminiferal-, and glauconite-bearing arkose. It is well to very well sorted and contains fine- to very fine-grained sand grains which compose from 2 to 15% of the unit. The lithosome is poorly indurated and has a gradational basal contact (within 20 to 50 em) with the fossiliferous sandstone lithosome. The sandy mudstone occurs interbedded with the fine sandstone and is in sharp contact with this unit. It is also in sharp contact with the overlying Kreyenhagen shale in all areas except in the Domengine Creek section where it is overlain by the fine sandstone lithosome. The lithosome contains plant and wood fragments, fish scales, foraminifera (Table 5), and casts of macrofossils. The macrofossils are too poorly preserved to be identified accurately. The most common foraminifera found within this lithosome include Anomalina, Cibicides, Discorbis, Elphidium, Eponides, Globoratalia, Robulus, and Tritaxia. The vast majority of the fauna is from the Rotaliina suborder. The ostracods present are predominantly ornamented and the planktonic forams are relatively uncommon and represent less than 5% of the fossil assemblage. Interpretation The sandy mudstone lithosome is similar to the transition zone deposits described by Reineck and Singh (1975). The unit is finer grained than the underlying lower shoreface deposits (fossiliferous sandstone), but coarser than the overlying shelf and bathyal shales of the Kreyenhagen Formation. This 68 gradation in grain size is a primary characteristic of this depositional environment. Fine sandstone beds (much like those of the fine sandstone lithesome) occur interbedded within the transition zone deposits. Primary sedimentary structures in the transition zone can be totally destroyed by the high degree of bioturbation. These burrowing organisms create a structureless deposit consisting of a homogenous sediment mixture (Howard, 1972; Reineck and Singh, 1975), much like that of the sandy mudstone lithesome. The transition zone is also characterized by a wide variety of species. The sandy mudstone lithesome contains macrofossils as well as a large assemblage of microfossils. The microfossils present in this lithesome are very similar to those found in the fossiliferous sandstone lithesome. The sandy mudstone has an average alpha index of seven which plots into the region of a marine shelf environment of normal salinity (Fig. 20). The low percentage of planktonic forams also indicates a shelf environment. The genera most abundant in this lithesome are most commonly found in normal marine waters of the inner shelf at depths of 0 to 50 m (Murray, 1973). GLAUCONITIC SANDSTONE Description The glauconitic sandstone lithesome crops out at the top of the Domengine Formation in the type area. The unit is very light gray (N8), dark yellowish orange (1 OYR 6/6), and grayish green (.5G 5/2) on fresh surfaces. It weathers to dark yellowish orange (lOYR 6/6), moderate red (5R 4/6), and light brown (5YR 5/6). It is well exposed and is slope forming. 69 The lithesome is tabular and is approximately 5 m thick (Fig. 9). It is structureless (90 to 100% bioturbated) and individual burrows are rare. The unit contains rounded, spherical, calcareous concretions. These concretions occur in a band across the lithesome and range from 40 to 70 em in width. The unit consists of moderately sorted fine- to medium-grained sandstone: calcitic mature glauconite-bearing arkose. Sieve analysis of the lithesome revealed that it has a median grain size of coarse silt, is very poorly sorted, strongly fine skewed, and mesokurtic. The lithosome is characterized by a very high percentage (10 to 25%) of glauconite. This glauconite is rounded and medium grained. The percentage of this mineral varies in hand specimen due to mottling. The glauconitic sandstone is poorly indurated and uncemented throughout most of the unit. It is in sharp contact with the underlying fine sandstone and with the overlying Kreyenhagen Formation. The lithesome is predominantly unfossiliferous, however calcareous worm tubes (Spiroglyptus) were found in a concretion. These tubes are 8 mm wide and 2 em iong and are poorly preserved. The spherical concretions within this unit are surrounded by a diagenetic color sequence. They are covered with a grayish black (N2) gypsiferous layer topped by consecutive colored layers of powdery white (N9), light brown (5YR 5/6), moderate red (5R 4/6), and dark yellowish orange (lOYR 6/6). This is the same color sequence found in the fine sandstone lithosome. 70 Interpretation The glauconitic sandstone lithesome is very similar to the lower shoreface deposits of the fossiliferous sandstone lithesome. Both units are thoroughly bioturbated and have a similar rock texture and composition. The two lithosomes differ primarily in the amount of glauconite and the faunal assemblage present. The large accumulation of glauconite within the glauconitic sandstone lithesome required 1) a slow sedimentation rate, 2) slightly reducing conditions, 3) only a slight agitation of the water, and 4) depths ranging from 18 to 730 m (Pettijohn, 1975; Selley, 1982). Therefore this lithesome was deposited on the lower shoreface on a very low-energy coastline. The sedimentation rate slowed significantly following the deposition of the underlying lithosomes. Increasing reducing conditions hampered the accumulation of a large fossil community like that of the underlying fossiliferous sandstone lithesome. The amount of bioturbation, however, was uneffected. DIAGENESIS OF THE FORMATION Diagenetic minerals of the Domengine Formation include limonite and hematite, calcite in concretrons, and satin-spar gypsum cystals. They are scattered throughout the Domengine and other formations in the area. Petrographic analysis of the calcareous concretions reveals that the calcite is replacing the clastic grains and in some areas forms a luster-mottled (poikilitic) texture. Dolomite rhombs are present in some thin sections. The green splotches which occur in the fossiliferous sandstone 7 1 lithesome were caused by the reduction of ferric iron next to plant fragments or organic material. Groundwater removes the ferrous ions leaving an iron poor green spot within a red, iron-rich matrix (Blatt, 1982). The diagenetic origin of color banding around the gypsum-cemented, fine sandstone bed and concretions of the glauconitic sandstone is not known. The majority of grain contacts observed in thin section consist of an equal percentage of point and long contacts. In portions of the Domengine Formation however, there has been compaction. In these areas, the grain contacts are predominantly (90%) long grain contacts. PALEOGEOGRAPHY AGE AND CORRELATION The Domengine Formation is of late early through early medial Eocene age (Fig. 23). This age designation is based upon the molluscan fauna and foraminifera found within the unit. The Domengine Formation contains macrofossils which are indicative of the West Coast provincial molluscan "Domengine Stage". The molluscs include Turritella andersoni lawsoni, Turritella uvasana aedificata, Venericardia (Pacificor) hornii calafia?, Lyria andersoni, Molopophorus cretaceus, Oleguahia domenginica, Pitar (Lamelliconcha) joaguinensis, and Dentalium (Laevidentalium) calafium. Based on work by Vokes (1939), Merriam (1941), Givens (1974), Givens and Kennedy (1979), Saul (1983), Kappeler (1984), Kappeler and others (1984), and Squires (1984), these taxa are restricted to the "Domengine Stage". Many of these taxa were found during the course of this present study (Table 4). The reference area for the "Domengine Stage" of Clark and Vokes (1936) is located within the study area. For a detailed review of the history of this stage, see Squires (1984). Mallory (1959) assigned the Domengine Formation of the Oil City area to his West Coast benthonic foraminiferal Ulatisian Stage. Although his stages are time transgressive, the Ulatisian Stage occurs within the molluscan "Domengine Stage". Laiming (1940a, 1940b, 1943) assigned this same fauna to his B-1 and B-lA benthonic foraminiferal zones. The Domengine Formation contains the foraminifera, Cibicides coalingensis (now referred to as Discorbis coalingensis) which is characteristic of the B-1 zone 72 PLANKTONIC CALCAREOUS NANNOPLANKTO~ BENTHIC FORAMINIFERAL w ::t: Pacific Coast .J u STANDARD FORAMINIFERAL Provincial STUDY <( ::t: 0 ZONES ZONES STAGES u u a. ZONES Molluscan Stages en 0 w Berggren, Okada and Loiming AREA a. m AGES Martini Mallory lark a Vokes0936 c w ::J and others Bukry (1940o, 1940b en (1971) (1959) Givens~:974) :::!: (1985) (1980) 1941ll Soul 1984) Pl2 A-1 "Tejon" p II t-·----- KREYENHAGEN w N15 CP 13 - .J A-2 NARIZIAN 0 FORMATION 0 LUTETIAN ...... w i f------z A-3 w "Transition" 50- u ------0 ,.." w / PIO BI-A / CPI2b / - Nl4 . . . - ..... DOMENGINE -~ "Domengine" CPI2o B-1 ULATISIAN 1 FORMATION P9 I >- Nl3 ...J YPRESIAN CP II I 0:: r---- <( I 1------b1 rJ-'] '? 1? -?r w II P8 Nl2 B-2 I "capay YOKUT CP 10 55- / FORMATION Figure 23. Correlation chart of the Domengine Formation with various authors for comparison of the age assignment (modified from Kappeler, 1984; and Squires, 1984) . -...! w p ' 74 (Table 5). Anomalina coalingensis is also present in the Domengine Formation and is restricted to zones B-1 through B-4 (Fig. 23). The fauna of the Domengine Formation can be correlated to many deposits within California. The molluscs are very similar to those reported by Vokes (1939), Stewart (1946), Kappeler (1984), and Kappeler and others (1984) of the Avenal Formation of Reef Ridge. Many of the molluscs which occur in the Domengine Formation, also occur in the Llajas Formation of Simi Valley (Squires, 1984). The Domengine fauna is also correlative to the Turritella uvasana applinae fauna ("Domengine Stage") of the upper half of the Juncal Formation of the Pine Mountain area (Givens, 1974). All three members of the La Jolla Group (Mount Soledad, Ardath Shale, and Scripps Formation) of the San Diego area contain typical "Domengine Stage" fauna such as Turritella andersoni lawsoni and Ostrea idriaensis (Givens and Kennedy, 1979). The macrofauna of the "Domengine"-age, unnamed sandstone strata of the lower Piru Creek region of the Transverse Ranges (Squires, 1977) is very similar to the fauna of the Domengine Formation. DOMENGINE-KREYENHAGEN UNCONFORMITY The contact between the Domengine and Kreyenhagen Formations is very abrupt in the Domengine Creek, Salt Creek, and Coalmine Canyon sections. In the Domengine Creek and Salt Creek sections, the middle and lower shoreface deposits of the Domengine are overlain by the offshore deposits of the Kreyenhagen Formation. In a normal transgressive sequence the depositional environments would indude middle shoreface, lower shoreface, transition zone, and offshore deposits (Reading, 1978). Therefore 75 several environments are missing in these sections. White (1940) stated that this contact was erosional in the Salt Creek region, the evidence being a substantial change in thickness of the Domengine in the general vicinity of Martinez Creek (Fig. 2). In this area the formation is only 7 m thick versus a thickness of 51 m only 739 m (2,400 ft.) away. In addition, White (1940) noted that fossiliferous beds which parallel the basal contact in the thicker sections were not present in Martinez Creek. Therefore, the contact between the Domengine and Kreyenhagen Formations is unconformable in Salt Creek and the type area. In Coalmine Canyon, the contact between the Domengine and Kreyenhagen is also very abrupt. The upper portion of the Domengine consists of interdistributary bay beach deposits. The interdistributary bay shales and shelf deposits normally found in a transgressive sequence (Reading, 1978) are not present. Kappeler (1984) noted a similar lack of transitional environments throughout the Reef Ridge area between the Avenal and Kreyenhagen Formations. She attributed this to the erosion of the transitional deposits similar to what has occured in the Salt Creek region. This may also have occurred in the Coalmine Canyon area where erosion of transitional deposits resulted in an unconformity between the Domengine and Kreyenhagen Formations. Another explanation for the "missing" environments in Coalmine Canyon is that they are actually represented in this section by a 1-m-thick interbedded sandstone and siltstone bed at the base of the Kreyenhagen Formation (Fig. 5B) (AI Almgren, personal communication). This deposit has a different character than the rest of the Domengine and Kreyenhagen ,, . 76 Formations. This type of deposit may have resulted from quick subsidence in which the rate of subsidence exceeded the rate of sedimentation. The presence of an unconformity, however, appears to be the best explanation, due to the lack of transitional deposits in the Domengine and Avenal Formations in the Salt Creek and Reef Ridge areas, respectively. The Domengine is not present for approximately 4 km north of Los Gatos Creek (Fig. 2) where the Keyenhagen lies directly on the Cretaceous Moreno Shale. This pinchout may represent 1) nondeposition of the formation due to the presence of a rocky promontory or 2) erosion of the Domengine deposits. The presence of a rocky promontory is the simplest solution that accounts for the lack of Domengine strata and that also fits the paleogeography of the area (Fig. 15). The uplift and erosion of the transitional deposits in the Salt Creek, Domengine Creek, and Coalmine Canyon area was followed by rapid subsidence throughout the study area. This erosion and subsidence was of short durtion, thereby leaving no paleontological evidence for an unconformity. PROVENANCE The Domengine Formation consists predominantly of submature arkose (Table 1). Folk (1974) states that a submature arkose is indicative of a mild tectonic setting during sedimentation. The formation of an arkose requires quick erosion of the source material and relatively rapid deposition in order to preserve the unstable grains (Folk, 1974). 77 The heavy mineral studies, petrographic analysis, and conglomerate clast analysis of the Domengine Formation reveal that the source terrain consisted predominantly of sedimentary and granitic rocks, as well as some high rank metamorphic rocks. Because the Domengine Formation unconformably overlies the Panoche, Moreno, Lodo, and Yokut Formations, it is possible that these formations were eroding within the Domengine source area. The conglomerate clasts and heavy minerals of the Panoche and Yokut Formations are very similar to that of the Domengine (Table 1, Fig. 24). The Panoche Sandstone is arkosic, and contains subangular to angular grains and fresh feldspar and quartz fragments (Table 1, Fig. 24). A sedimentary source is suggested by the roundness of the heavy minerals and conglomerate clasts. A sedimentary source is also suggested by the presence of sandstone, chert, quartzite, jasper, and shale clasts. The pebble conglomerate lithesome of Coalmine Canyon contains a large percentage of sedimentary rock fragments (Table 3). Many of these clasts are derived from the underlying Panoche Formation. The rock composition of the Domengine in Coalmine Canyon varies slightly from that of the other sections (Fig. 24). This variation is possibly due to further reworking and transport of these sediments prior to deposition on the delta. The Domengine contains forams which are believed to be reworked from a sedimentary rock source (Table 5). These forams represent a bathyal environment {Ingle, 1980) and are common in deep marine deposits such as the Lodo and Moreno Formations. Q MEAN (Domengine Rocks) MEAN ){ X Qs1F37 R" lLJ X (f) 0 ~ Q:" <:{ u ,_:r: -1 F - · 1=1 1=3 R K --· 1=1 1:3 p A YOKUT FORMATION Q: QUARTZ K = POTASSIUM FELDSPAR • PANOCHE FORMATmN F = FELDSPAR P : PLAGIOCLASE FELDSPAR DOMENGINE FORMti,TION R : ROCK FRAGMENTS ® Coolmine Canyon Section Other Sections Figure 24. Ternary diagrams showing the composition of rocks from the Domengine, Panache, and Yokut Formations (based on Folk, 1974). The composition and location of each sample plotted above is shown on Table 1. -.I ro 79 The Franciscan complex is believed to be a major source for the Domengine Formation in the Vallecitos area (Fig. 12) (Nilsen and Clarke, 1975). The Franciscan Formation was also eroding within the source terrain of the Domengine Formation in the study area. This source is indicated by the presence of glaucophane (Table 2) and red chert clasts (Table 3) which are characteristic of the Fanciscan complex (White, 1940; Bailey, 1966; Nilsen, 1981). Nilsen and Clarke (1975) believed that the Salinian Block and Sierra Nevada Batholith were major sources for the Domengine Formation. These granitic sources, however, were too far away from the study area to contribute large amounts of sediment to the Domengine Formation. In addition, sediment derived from the Sierra Nevada would have had to cross the San Joaquin Valley depositional basin and move "uphill" onto the shallow marine deposits of the Domengine Formation. The most likely province, therefore, are the Paleocene and Mesozoic sedimentary rocks to the west of the present outcrops. PALEOGEOGRAPHY Climate The Pacific Coast during the Eocene experienced a subtropical climate from Washington to Peru (Durham, 1950; Squires, 1984). Peak temperatures in the Eocene occurred between 53 and 49 Ma (early to middle Eocene). This peak was probably the warmest period in the Cenozoic (Kennett, 1982). Vokes (1939) listed the following 31 genera from the Domengine Formation which 80 can be compared to modern taxa and have living representatives in tropical waters (Vokes, 1940; Durham, 1950; Addicott, 1970; Squires, 1984): Pinna, Pteria, Pedalion, Spondylus, Crassatellites, large Venericardia, Miltha, Macrocallista, Pitar, Pelecyora, Corbula; and the gastropods Akera, Terebra, Conus, Olivella, Ancilla, Voluta?, Lyria, Harpa, Pseudoliva, Ficopsis, Cypraea, Rimella, Terrebellum, Potamides, Turritella, Architectonica, Xenophora, Eocernina, Nerita, and Velates. This assemblage indicates that the Domengine Formation was deposited in water warmer than 20°C (Vokes, 1940; Durham, 1950). The Avenal Formation was deposited in a subtropical climate (Kappeler, 1984) and the presence of coal in the Alcalde Hills is also indicative of warm tropical climates. Tropical environments are condusive to the production and preservation of organic material and peat deposits form a large bulk of the subaerial deposits (Coleman, 1982). Paleogeography The Domengine Forn1ation in the Alcalde Hills rests unconformably on the Cretaceous age deposits of the Panache Formation. This hiatus is not present north of Oil City. In this region there is a fairly continuous sequence of Cretaceous through early Eocene deposits beneath the Domengine. A paleo high is therefore inferred to have been present in the Alcalde Hills area at some time between the Cretaceous and late early Eocene which resulted in the erosion or nondeposition of the Paleocene and early Eocene deposits. A depositional basin was present, however in the northern half of the study area. This depositional basin was filled with the sandstones and shales of the 81 Lodo and Yokut Formations. There were intermittant periods of erosion resulting in a few minor unconformities. The unconformable contact between the Domengine and Yokut sandstones extends from the Oil City area into East San Carlos Creek where the two formations become undivided (Fig. 13) (Nilsen, 1981). The hiatus resulted from a minor uplift and the subsequent erosion that extended through the study area to San Carlos Creek. The study area subsided in the late early Eocene. This regional subisdence resulted in a westward marine transgression and the deposition of the Domengine Formation. A rocky coastline was possibly present from Los Gatos Creek to Salt Creek (Fig. 25). This rocky coastline extended into the shorface zone of the beach and possibly prevented the deposition of foreshore and backshore deposits. A low rocky promontory, in the Los Gatos Creek region (Fig. 2.5) prevented the deposition of shallow-marine rocks of the Domengine Formation. The coastline was relatively low energy. In the southern portion of the study area, river brought sediment to this low-energy coastline and formed a prograding river-dominated delta. This deita extended down to the Reef Ridge area (Fig. 11) and is also evident in the rocks of the Avenal Formation (Fig. 26). The rocks of Coalmine Canyon were deposited predominantly along the margin of an active distributary channel, near an interdistributary bay. The occurence of coal seams within the Alcalde Hills (Fig. 3) indicates that swamps were present throughout an area at least 2.5 km wide (Fig. 25). The continual subsidence resulted in the deposition of transition zone deposits throughout the northern portion of the study area (Fig. 26). There was intermittent storm activity which stirred up the sediment of the 8 2 ~ ' ·· .. \.., LEGEND '· ... ..,. . sc Salt Creek \.~sc DC Domengine Creek \~Middle Shoreface SB Section 8 \ "-: ....\ .., ...... oc Oil City Peak \ SA Section A \ \ CMC Coal mine Canyon ~Lower Shoreface ~ Transition Zone Shelf . '. Figure 25. Paleogeography of the study area during the deposition of the Domengine Formation. 83 ······.,~ Lower Shoreface ~ ~" ... '·. ·...... ·...... ·. •, ·· .. ·...... , .. ...c---.. --- ~ ..c--- LEGEND -- AIC'"'-...... --...... CMC Coalmine Canyon ------.. zc Zapata Canyon} Reef Rg. ~ GC Garza Canyon Avenal Fm, Figure 26. Paleogeography of the Alcalde Hills and Reef Ridge during the deposition of the Domenaine Form- ation. 84 shoreface and transition zone. This storm activity resulted in the deposition of thin sandstone beds and storm gravels. Uplift at the end of the early medial Eocene resulted in the erosion of the transitional deposits of the Salt Creek and Coalmine Canyon area. This erosion was followed by quick subsidence and the subsequent deposition of the Canoas Siltstone member of the Kreyenhagen Formation throughout the study area. DOMENGINE-A VENAL EQUIVALENCE The Domengine and Avenal Formations are the same stratigraphic unit. Harun (1984) has shown these units to be continuous with each other in the subsurface. The depositional environments distinguishable within the Avenal are very much like those of the Domengine Formation and include lower and upper shoreface deposits, transgressive lag, and sandflat and tidal channel deposits of a tidal-dominated delta (Kappeler and others, 1984; Kappeler, 1984). The tidal-dominated delta deposits of the Avenal are probably part of the same deltaic complex which formed the Domengine Formation in the Alcalde Hills (Fig. 26). The presence of tidal-dominated and fluvial-dominated lobes on the same deltaic complex occurs_ on the Mississippi delta. Individual lobes of this delta are known to prograde, become abandoned, and then transgress. During the transgressive phase, tidal processes play a major role in reshaping the depositional environments found on the lobe. On the Plaquemines lobe of the Mississippi delta of the Quatre Bayou Pass area, Louisiana, the tidal range is only 40 em. These tidal currents, however, have formed tidal channels, 85 flood-tidal deposits, and ebb-tidal delta deposits. The tidal channels occupy abandoned distributary channels and the flood-tidal delta deposits "form a landward-prograding planar sand sheet". With increased exposure to these tidal currents, the sediments become progressively coarser (Howard, 1982). Therefore, the tidal-dominated delta deposits of the Avenal represent an abandoned lobe of the fluvial-dominated delta which formed the Domengine Formation in the Alcalde Hills. This abandoned lobe was in the transgressive phase and could not withstand the influence of relatively small tidal currents. The Avenal was named by Anderson in 1905. This name has priority over the name Domengine which was first used by Clark in 1926. Therefore, the name "Domengine" needs to be suppressed. REFERENCES Addicott, W. 0., 1970, Tertiary paleo dim a tic trends in the San Joaquin Basin, California: United States Geological Survey Professional Paper 644-D, 19 p. Adegoke, 0. S., 1969, Stratigraphy and paleontology of the marine Neogene formations of the Coalinga region, California: University of California Publications in Geological Sciences, v. 80, 241 p. Anderson, F. 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E., 1964, Minor sedimentary structures in a prograding distributary: Marine Geology, v. 1, no. 3, p. 240-258. Colemen, J. M., and Prior, D. B., 1982, Deltaic environments of deposition, in Scholle, P. A., and Spearing, D., eds., Sandstone depositional environments: American Association of Petroleum Geologists Memoir 31, p. 139-178. 89 Givens, C. R., and Kennedy, M.P., 1979, Eocene molluscan stages and their correlation, San Diego area, California, in Abbott, P. L., ed., Eocene depositional systems, San Diego: Societyof Economic Paleontologists and Mineralogists, Field Trip Guide, Geological Society of America Annual Meeting, p. 81-95. Goddard, E. N., Compiler, 1980, Rock color chart: Boulder, Colorado, Geological Society of America, 8 p. Goldring, R., and Bridges, P., 1973, Sublittoral sheet sandstones: Journal of Sedimentary Petrology, v. 43, p. 736-74 7. Hornaday, G. R., 1974, Historical determination of the base of the Paleocene in the Panoche Creek area, in Payne, M ., ed., The Paleogene of the Panoche Creek-Cantua Creek area, central California: Society of Economic Paleontologists and Mineralogists, Special Publication, p. 25-27. Howard, J.D., 1971, Comparison of the beach-to-offshore sequence in modern and ancient sediments, in Howard, J.D., Valentine, J. W., and Warme, J. E., eds., Recent advances in paleoecology and ichnology: American Geological Institute Short Course Lecture Notes, p. 148- 183. Howard, P. C., 1982, Tidal deposits of Quatre Bayou Pass, Louisiana, in Nummedal, D ed., Deltaic sedimentation on the Louisiana coast: Gulf Coast Section Society Economic Paleontologists and Mineralogists Spring Field Trip Guidebook, p. 92-100. Howard, J. D., and Reineck, H. E., 1972, Georgia coastal region, Sapelo Island, U.S.A.: sedimentology and biology. IV. Physical and biogenic sedimentary structures of the nearshore shelf: Senckenbergiana Maritima, v. 4, p. 81-123. Harun, H., i 984, Distribution and deposition of lower to middle Eocene strata in central San Joaquin Valley, California: Stanford Univeristy unpublished Masters thesis, 100 p. Ingle, J. C., Jr., 1980, Cenozoic paleobathymetry and depositional history of selected sequences within the southern California continental borderland: Cushman Foundation for Foraminiferal Research, Special· Publication, No. 19, p. 163-195. Kappeler, K. A., 1984a, Deposi tiona! environments of the A venal Sandstone of Reef Ridge, central California: California State University, Northridge unpublished Masters thesis, 86 p. Kappeler, K. A., Squires, R. L., and Fritsche, A. E., 1984b, Transgressive marginal-marine deposits of the Avenal Sandstone, Reef Ridge, central California, in Blueford, J. R., ed., Kreyenhagen and related 90 ~ ' rocks: Society of Economic Paleontologists and Mineralogists Publication, p. 9-27. Kennett, J.P., 1982, Marine geology: New Jersey, Prentice-Hill, 813 p. Kolb, C. R., and Van Lopik, J. R., 1966, Depositional environments of the Mississippi River deltaic plain- southeastern Louisiana, in Shirley, M. L., and Ragsdale, J. A., eds., Deltas in their geologic framework: Houston Geologic Society Special Publication, p. 17-60. Kumar, N., and Sanders, J. E., 1976, Characteristics of shoreface storm deposits: Modern and ancient examples: Journal of Sedimentary Petrology, v. 46, no. 1, p. 145-162. Laiming, B., 1940a, Some foraminiferal correlations in the Eocene of the San Joaquin Valley, California: Sixth Pacific Science Congress Proceedings, v. 2, p. 538-568. ---- 1940b, Foraminiferal correlations in Eocene of San Joaquin Valley, California: American Association of Petroleum Geologists Bulletin, v. 24~ p. 1923-1939. 1943, Eocene foraminiferal correlations in California, in Geologic formations and economic development of the oil and gas fields of California: California Division of Mines Bulletin 118, pt. 2, ch. 6, p. 193-198. Mallory, V. S., 1959, Lower Tertiary biostratigraphy of the California Coast Ranges: American Association of Petroleum Geologists, 416 p. Mansfield, C. F., 1972, Petrofacies units and sedimentary facies of the Late Mesozoic stata west of Coalinga, California, in Steinert, R. E., ed., Cretaceous of the Coalinga area: Society of Economic Paleontologists and Mineralogists, Pacific Section, Fall Field Trip Guidebook, p. 19-26. Martini, E., 1971, Standard Tertiary and Quaternary calcareous nannoplankton zonation, in Farinacci, A., ed., Proceedings of the Second International Conference on planktonic microfossils, Rome 1970, v. 2, p. 739-786. Milam, R. W., 1984, Late e"arly to late middle Eocene planktonic foraminiferal zonations in California, in Blueford, J. R., ed., Kreyenhagen and related rocks: Societyof Economic Paleontologists and Mineralogists Special Publication, p. 51-66. Murray, J. W., 1973, Distribution and Ecology of living benthic foraminifends: New York, New York, Crane, Russak and Company Inc., 274 p. 91 Nilsen, T. H., 1981, Early Cenozoic stratigraphy, tectonics and sedimentation of the central Diablo Range between Hollister and New Idria, in Frizzell, V., ed., Geology of the central and northern Diablo Range, California: Society of Economic Paleontologists and Mineralogists Special Publication, p. 21-34. Nilsen, T. H., and Clarke, S. H., Jr., 1975, Sedimentation and tectonics in the early Tertiary continental borderland of central California: United States Geological Survey Professional Paper 925, 64 p. Okada, H., and Bukry, D., 1980, Supplementary modification and introduction of code numbers to the low-latitude coccolith biostratigraphic zonation (Bukry 1973-1975): Marine Micropaleontology, v. 5, p. 321-325. Pettijohn, F. J., 1975, Sedimentary rocks: New York, Harper and Row, 628 p. Powers, M. C., 1953, A new roundness scale for sedimentary particles: Journal of Sedimentary Petrology,v. 23, p.ll7-119. Ragan, D. M., 1973, Structural geology, an introduction to geometrical techniques: New York, John Wiley and Sons, second edition, 208 p. Reading, H. G., 1978, Sedimentary environments and facies: New York, Elsevier Publications, 569 p. Reineck, H. E., and Singh, I. B., 1975, Depositional sedimentary environments: New York, Springer-Verlag Publishers, 439 p. Saul, L. R., 1983, Notes on Paleogene turritellas, venericardias, and molluscan stages of the Simi Valley area, California, in Squires, R. L., and Filewicz, M. F., eds., Cenozoic geology of the Simi Valley area, southern California: Society of Economic Paleontologists and Mineralogists, Pacific Section, Volume and Guidebook, p. 71~80. Selley, R. C., 1982, An introduction to sedimentology: London, Academic Press, 417 p. Squires, R. L., 1977, Eocene molluscan assemblage and stratigraphy, lower Piru Creek, Transverse Ranges, California: California Division of Mines and Geology Special Report, v. 129, p. 81-86. ----- 1984, Megapaleontology of the Eocene Llajas Formation, Simi Valley, California: Natural History Museum of Los Angeles County, Contributions in Science, no. 350, 76 p. Steinmeyer, E. H., 1972, Pacific Gas and Electric Company pipeline trench section, Kings County, California, in Rennie, E. W ., Jr., ed., Guidebook: geology and oil fields, west side central San Joaquin Valley: American Association of Petroleum Geologists, Society of 92 Exploration Geophysicists, Society of Economic Paleontologists and Mineralogists, Pacific Sections, 47th Annual Meeting, p. 70-71. ----- 1974, Biostratigraphy of the Paleocene-Eocene in the vicinity of Salt Creek, Fresno County, California, in Payne, M., ed., The Paleogene of the Panoche-Cantua creek area: Society of Economic Paleontologists and Mineralogists Special Publication, p. 69-84. Swift, D. J. P., 1968, Coastal erosion and transgressive stratigraphy: Journal of Geology, v. 76, p. 444-456. ---- 1975, Barrier-island genesis: evidence from the central Atlantic shelf, easternU.S.A.: SedimentaryGeology, v.14, p. 1-14. Van Heerden, I. L. 1982, Deltaic sedimentation in Atchafalaya Bay (South central Louisiana), in Nummedal, D. ed., Deltaic sedimentation on the Louisiana coast: Gulf Coast Section Society of Economic Paleontologists and Minerologists Special Public.ation, p. 40-61. Vokes, H. E., 1939, Molluscan faunas of the Domengine and Arroyo Hondo Formations (Fresno County) of the California Eocene: New York Academy of Science Annuls, v. 38, 246 p. ----- 1940, Paleoecology of the fauna of the Domengine Formation, middle Eocene, California: 6th Pacific Science Congress, Proceedings, v. 2, p. 597-605. Von Estroff, F. E., 1930, K reyenhagen shale at type locality, Fresno County, California: American Association of Petroleum Geologists, Bulletin, v. 14, no. 10; p. 1321-1336. Weaver, C. E., and others, 1944, Correlation of marine Cenozoic formations of western North America: Geological Society of America Bulletin, v. 55, p. 569-598. Wentworth, C. K., 1922, The shapes of beach pebbles: United States Geological Survey Professional Paper 131-C, p. 75-83. White, R. T., 1940, Eocene Yokut Sandstone north of Coalinga, California: American Association of Petroleum Geologists, Bulletin, v. 24, no. 10, p. 1722-1751. Zingg, T., 1935, Beitrage zur Scholtteranalyse: Min. Petrog. Mitt Schweiz., v. 15, p. 39-140. APPENDIX 1 LOCATION OF MEASURED SECTIONS Coalmine Canyon section, T.20S., R.15E., Coalinga 7.5 minute quadrangle, California. Section A and Oil City sections, T.19S., R.15E., Domengine Ranch 7.5 minute quadrangle, California. 93 94 Section B, section 9, T.19S., R.15E., Domengine Ranch 7.5 minute quadrangle, California. Domengine Ranch section, T.18S., R.15E., Domengine Ranch 7.5 minute quadrangle, California. Salt Creek section, R.14E., Joaquin Rocks quadrangle, California. APPENDIX 2 MACROFOSSIL LOCALITIES All are California State University, Northridge localities. 860. At an elevation of 1,200 ft in the basal pebble bed of the Domengine at the type area, 2,200 ft (679 m) east and 720ft (222m) north of the southwest corner of section 29, T.18S., R.15E., Domengine Ranch 7.5-minute quadrangle, 1956. 861. At an elevation of 1,230 ft at the top of the ridge in the type area, 2,200 ft (679 m) east and 720 ft (222 m) north of the southwest corner of section 29, T.l8S., R.15E., Domengine Ranch 7.5-minute quadrangle, 1956. · 862. At an elevation of 1,240 ft in the concretion zone on the top of the ridge, 2,200 ft (679 m) east and 720 ft (222 m) north of the southwest corner of section 29, T.18S., R.15E., Domengine Ranch 7.5-minute quadrangle, 1956. 863. At an elevation of 1,360 ft in the basal conglomerate zone along ridge, 1,500 ft (463 m) east and 1,400 ft (432 m) south of the northwest corner of section 15, T.19S., R.l5E., Domengine Ranch 7.5-minute quadrangle, 1956. 8611-. At an elevation of 1, 740 ft in the basal pebble bed, 680 ft (210m) west and 100ft (31 m) north of the southeast corner of section 17, T.19S., R.15E., Domengine Ranch 7.5-minute quadrangle, 1956. 865. At an elevation of 1,420 ft in the small resistant ridge of the basal Domengine, 1,600 ft (494 m) north and 1,360 ft (420 m) south of the northeast corner of section 9, T.19S., R. 15E., Domengine Ranch 7.5-minute quadrangle, 1956. &66. At an elevation of 1,040 ft in the top portion of the Domengine within the canyon, 150ft (46 m) east and 1,800 ft (556 m) south of the northwest corner of section 36, T.20S., R.14E., Coalinga 7.5-minute quadrangle, 1956. 867. At an elevation of 1,035 ft near the waterfall within the canyon, 170 ft (52 m) east and 1,800 ft (556 m) south of the northwest corner of section 36, T.20S., R.14E., Coalinga 7.5-minute quadrangle, 1956. 868. At an elevation of 1,035 ft at the waterfall within the canyon, 175 ft (54 iTIT east and 1,800 ft (556 m) south of the northwest corner of section 36, T.20S., R.14E., Coalinga 7.5-minute quadrangle, 1956. 869. At an elevation of 1,470 ft in the resistant bed on the ridge and within the small canyon, 1,975 ft (610 m) west and 1,400 ft (432 m) north of the northeast corner of section 9, T.19S., R.l5E., Domengine Ranch 7.5-minute quadrangle, 1956. 95 96 !70. At an elevation of 2,100 ft along the top of the ridge, 2,350 ft (725 m) west and 1,300 ft (401 m) south of the northeast corner of section 9, T.19S., R.15E., Domengine Ranch 7.5-minute quadrangle, 1956. !71. At an elevation of 2,085 ft within the resistant bed along the ridge, 250 :ftT77 m) west and 2,650 ft (818 m) south of the northeast corner of section 17, T.19S., R.15E., Domengine Ranch 7.5-minute quadrangle, 1956. 872. At an elevation of 2,090 ft above the resistant bed along the ridge, 250 ft (77 m) west and 2,650 ft (818 m) south of the northeast corner of section 17, T.l9S., R.15E., Domengine Ranch 7.5-minute quadrangle, 1956. Q ' APPENDIX 3 MICROFOSSIL SAMPLE LOCALITIES * Sample contained foraminifera or radiolarians, those locality numbers without the asterics were barren samples. 101* 2,160 ft (667 m) west and 410ft (127m) south of the northeast corner of section 9, T.19S., R.15E., at an elevation of 1,530 ft at the base of the Kreyenhagen Formation. 102 2,130 ft (675 m) west and 400ft (123m) south of the northeast corner of section 9, T.l9S., R.15E., at an elevation of 1,520 ft at the top of the Domengine Formation. 103* 2,165 ft (668 m) west and 415ft (128m) south of the northeast corner of section 9, T.19S., R.15E., at an elevation of 1,530 ft within the top portion of the Domengine Formation. 104* 2,170 ft (670 m) west and 420ft (130m) south of the northeast corner of section 9, T.19S., R.15E., at an elevation of 1,525 ft within the middle of the Domengine. 105* 2,210 ft (682 m) west and 420ft (130m) south of the northeast corner of section 9, T.19S., R.15E., at an elevation of 1,495 ft within the middle of the formation. 106* 2,270 ft (701 m) west and 440ft (136m) south of the northeast corner of section 9, T.19S., R.15E., at an elevation of 1,480 ft at the base of the Domengine. 107* 500ft (154m) west and 110ft (34m) north of the southeast corner of section 17, T.19S, R.15E., at an elevation of 1,865 ft in the upper 1m of the Domengine. 108 580 ft (179 m) west and 120 ft (37 m) north of the southeast corner of section 17, T.19S., R.15E., at an elevation of 1,840 ft in the middle of the Domengine. 109* 610ft (188m) west and 110ft (34m) north of the southeast corner of section 17, T.l9S., R.15E., at an elevation of 1,840 ft in the basal portion of the formation. 110 620 ft (191 m) west and 140ft (43 m) north of the southeast corner of section 17, T.19S., R.l5E., at an elevation of 1,830 ft near the base of the formation. 97 98 111 * 520ft (160 m) west and 100ft (31 m) north of the southeast corner of section 17, T.19S., R.15E., at an elevation of 1,860 ft near the upper portion of the Domengine. 112 500 ft (154 m) west and 110 ft (34 m) north of the southeast corner of section 17, T.19S., R.15E., at an elevation of 1,865 ft near the base of the Kreyenhagen. 113* 100 ft (31 m) east and 2,390 ft (738 m) north of the southwest corner of section 16, T.19S., R.15E., at an elevation of 1,940 ft at the top of the Domengine. 114 190 ft (55 m) east and 2,380 ft (734 m) north of the southwest corner of section 16, T.l9S., R.15E., at an elevation of 1,950 ft at the top of the formation. 115* 3,090 ft (954 m) west and 780 ft (241 m) north of the southwest corner of section 16, T.19S., R.15E., at an elevation of 1,245 ft in the middle portion of the Domengine. 116 3,100 ft (956 m) west and 740ft (228m) north of the southwest corner of section 16, T.l9S., R.15E., at an elevation of 1,240 ft in the middle portion of the formation. 117 3,150 ft (972 m) west and 800ft (247m) north of the southwest corner of section 16, T.19S., R.15E., at an elevation of 1,250 ft in the middle of the section. 118 2,990 ft (923 m) west and 840ft (259m) north of the southwest corner of section 16, T.19S., R.15E., at an elevation of 1,190 ft in the basal portion of the Kreyenhagen Formation. 119 2,990 ft (923 m) west and 840ft (259m) north of the southwest corner of section 16, T.l9S., R.15E., at an elevation of 1,200 ft at the top contact of the Domengine Formation within the Kreyenhagen Formation approximately 1 m above locality 118. 120 3,230 ft (997 m) north and 360ft 011 m) west of the southeast corner of section 27, T.20S., R.14E., Coalinga 7.5-minute quadrangle, 1956, at an elevation of 1,975 ft, 27 m below the Domengine Formation within the Cretaceous Panoche Formation. 121 200ft (62 m) west and 3,390 ft (1,046 m) north of the southeast corner of section 27, T.20S., R.14E., Coalinga 7.5-minute quadrangle, 1956, at an elevation of 1, 975 ft, 15 m below the basal Domengine contact within the Cretaceous strata. 99 122 170 ft (52 m) west and 3,330 ft (1,027 m) north of the southeast corner of section 27, T.20S., R.l4E., Coalinga 7.5-minute quadrangle, 1956, at an elevation of 1, 970 ft, 3 m below the Domengine within the Panoche Formation. 123 150 ft (46 m) west and 3,480 ft (1,074 m) north of the southeast corner of section 27, T.20S., R.14E., Coalinga 7.5-minute quadrangle, 1956, 12m above the base of the Domengine within the claystone. 124 70 ft (22 m) west and 3,490 ft (1,077 m) north of the southeast corner of section 27, T.20S., R.l4E., Coalinga 7.5-minute quadrangle, 1956, 25m above the base of the Domengine. 12.5 40ft (12m) west and 3,540 ft (1,093 m) north of the southeast corner of section 27, T.20S., R.14E., Coalinga 7.5-minute quadrangle, 1956, at an elevation of 1, 940ft, near the middle of the Domengine. 126* 100 ft (31 m) east and 2,390 ft (738 m) north of the southwest corner of section 16, T.19S., R.l5E., at an elevation of 1,930 ft in the middle of the Domengine. All localities are in the Domengine Ranch 7.5-minute quadrangle (1956) unless otherwise noted.