Subsurface Geology of the South Cuyama Oil Field and Adjacent Areas, Southern Coast Ranges, California

Home , Caliente Range, Cuyama Valley, La Panza Range, South Cuyama Oil Field

AN ABSTRACT OF THE THESIS OF

Hans Frederick Schwing for the degree of MASTER OF SCIENCE

in Geology presented on May 6, 1983

Title: SUBSURFACE GEOLOGY OF THE SOUTH CUYAMA OIL FIELD AND

ADJACENT AREAS, SOUTHERN CO SA RAlitE$2 CAIWORNIA Redacted for Privacy Abstract approved: Dr. Robert eats 071

Subsurface mapping was used to determine the structure and

geologic history of the South Cuyama dome and part of the Russell

fault in the South Cvyama oil field area. Deformed Late Cretaceous

and/or early Tertiary marine strata are unconformably overlain by

the late Oligocene to early Miocene Vaqueros Formation (Quail

Canyon Sandstone Member, Soda Lake Shale Member, and Painted Rock

Sandstone Member) northeast of the Russell fault. Rapid subsidence

abruptly downdropped shelf deposits in the transgressive Quail

Canyon Sandstone, ending shallow-marine deposition. Warping of the

Quail Canyon shelf formed elongate west-northwest-trending submarine

troughs and highs at the same time as the basinal Soda Lake Shale

Member was deposited. Locally, the Soda Lake Shale ponded in topo-

graphic lows floored by Quail Canyon Sandstone. In addition, pro-

grading turbidites of the Soda Lake Shale Member and shelf deposits

of the Painted Rock Sandstone thinned over the highs, including the

proto-South Cuyama dome. Renewed subsidence during the late Saucesian accompanied deposition of the Saltos Shale Member of the Monterey

Formation. Late Saucesian-early Relizian movement along the northeast-trending Cox normal fault set in part controlled further growth of the proto-South Cuyama dome and thinning of the Saltos

Shale over structural highs. Shelf and shallow-marine deposits of the Branch Canyon Sandstone and overlying undifferentiated

Branch Canyon Sandstone-Santa Margarita Formation (BCSM) prograded across the basin during the middle andlate Miocene. Major right-

slip along the Russell fault juxtaposed contrasting coeval strati-

graphic sections prior to deposition of the Pliocene(?)Morales(?)

Formation. Northeast-trending normal faults and northwest-trending

strike-slip faults formed across the dome during deposition ofthe

BCSM in response to right-lateral wrench faulting onthe Russell

fault. The Morales(?) Formation conformably overlies the BCSMand

probably represents the transition from marine to nonmarinedepo-

sition; the uppermost part possibly includesPleistocene alluvial

deposits. Right slip along the Russell fault was accompanied by

folding of at least the lowermost Morales(?) into thepresent-day

South Cuyama elongate dome subparallel to the Russellfault.

Right-stepping en echelon axial culminations on thedome were off-

set 4,500 feet right-laterally by the Russellfault.

The south-dipping South Cuyama thrust fault tectonically over-

rode the Russell fault, South Cuyama dome, andPleistocene alluvial deposits, folding and thrusting Eocene and younger strata of the

Sierra Madre Mountains northward. The north-dipping Morales fault thrust Paleocene to Miocene strata of the Caliente Range southward over Pliocene(?)-Pleistocene alluvial deposits during the late

Pleistocene. Between these two thrust faults is the present-day

Cuyama Valley.

Structures in the South Cuyama oil field and adjacent areas formed in response to recurrent right-lateral wrench tectonism along the Russell fault during the middle to late Miocene and possibly from latest Oligocene to Pliocene time. The complex faulting and folding associated with wrench tectonism are obscured by the Pleistocene-Holocene contractile regime. SUBSURFACE GEOLOGY OF THE SOUTH CUYAMA OIL FIELD AND ADJACENT AREAS, SOUTHERN COAST RANGES, CALIFORNIA

Hans Frederick Schwing

A THESIS

submitted to

Oregon State University

in partial fulfillment of the requirements for the degree of

Master of Science

Completed May 6, 1983

Commencement June 1984 APPROVED: Redacted for Privacy

Professor and Chairman of G(o ogy in charge of major

Redacted for Privacy

Dean of Graduate School (7

Date thesis is presented May 6, 1983

Typed by Therese Belden for Hans Frederick Schwing ACKNOWLEDGEMENTS

I would like to thank Dr. Robert S. Yeats forintroducing me

to the Cuyama basin and for his guidance andadvice throughout the

course of this project. William J. M. Bazeley and Thom Davis of

Arco Exploration Company deserve special thanks fortheir coopera-

tion, advice, and discussions of Cuyama basin geology. Barb Nevins

of Oregon State University discussed the subsurfacegeology of the

Cuyama Valley with me and provided many useful suggestions.

Karla Urbanowicz and Bill Gilimore of Oregon State helped

construct some of the cross sections. I am extremely grateful

to Edwin Howes for his superb draftingand extreme patience.

I would like to thank my colleagues at Oregon StateUniversity,

especially Dan Olson, for their friendship and discussionsduring

my stay at Oregon State. Therese Belden provided invaluable help

in the completion of this project. The 26th St. Beanery was instru-

mental in the writing of the thesis. Lamar and Isabelle Johnston

generously provided lodging at their ranch in CuyamaValley during

the summer of 1980.

I would especially like to thank my wife Maryand son Hans

for their continuous support and love. I would also like to thank

my parents, brothers, andsisters, especially Katrina, for their

encouragement and support during my studies.

This project was funded by a grant from theNational Science

Foundation (4! EAR-8022271) and a grant from theAtlantic Richfield

Company for field work during the summer of1980. This project could not have been completed without the support and cooperation of William J. M. Bazeley and the Atlantic Richfield Company, who provided well data, basemaps, and aerial photos for the study.

Dr. K. F. Oles and Dr. J. G. Johnson of Oregon State University reviewed the thesis and deserve special thanks. Cathy Hiebertof

Union Oil Company of California helped with some of thefinal typing. TABLE OF CONTENTS

INTRODUCTION 1 Regional Setting 1 Objectives 5 Methods 6 Previous Work 7

STRATIGRAPHY 9 General Statement 9 Unnamed Pre-Oligocene Marine Sedimentary Rocks 11 Simmler Formation 12 Vaqueros Formation 14 Monterey Formation 19 Branch Canyon Sandstone 22 Santa Margarita Formation 24 Branch Canyon Sandstone-Santa Margarita Forma- 28 tion Undifferentiated Morales(?) Formation 29 Alluvium 34

STRUCTURE 36 General Statement 36 "Vaqueros" Structure 36 Cox Faults 41 Russell Fault 43 South Cuyama Fault 51 Morales Fault 55 Tectonic Ridges 57

GEOLOGIC HISTORY 59

CONCLUSION 66

REFERENCES CITED 67 LIST OF FIGURES

Figure Page

1. Index map 2

2. Tectonic map of the Cuyama basin 3

3. Generalized regional geologic map of the Cuyama 4 basin area

4. Generalized stratigraphy of the Cuyama basin 10

5. Isopach map of the Johnston sand 25

6. Isopach map of the Branch Canyon Sandstone- 30 Santa Margarita Formation Undifferentiated

7. Isopach map of the basal Morales(?) Formation 33 claystone

8. Tectonic map 37

9. Evolution of the "Vaqueros" Structure 40

10. Offset isopachs along the 72-1 fault 48 LIST OF PLATES

Plate Pocket

I Well base map and cross section locations

II Well base map of South Cuyama oil field and cross section locations

III Geologic map of the South Cuyama area

IV Stratigraphic correlation chart across western Cuyama Valley

V Composite Type E-log for the South Cuyama oil field

VI Isopach map of the interval from electric log marker 17 in the Saltos Shale Member to the base of the Vaqueros Formation

VII Vaqueros Formation stratigraphic correlation section

VIII Cross section A-A'

IX Isopach map of an interval in the Saltos Shale Member of the Monterey Formation

X Cross section B-B'

XI Cross section C-C'

XII Cross section D-D'

XIII Cross section E-E'

XIV Cross section F-F'

XV Structure contour map of electric log marker 17 in the Saltos Shale Member of the Monterey Formation

XVI Structure contour map of electric log marker 17 in the Saltos Shale Member of the Monterey Formation in the South Cuyama oil field

XVII Structure contour map of the Russell fault Page Pocket

XVIII Structure contour map of electric log markers near the base of the Morales(?) Formation

XIX Structure contour map of the South Cuyama fault SUBSURFACE GEOLOGY OF THE SOUTH CUYAMA OIL FIELD AND ADJACENT AREAS, SOUTHERN COAST RANGES, CALIFORNIA

INTRODUCTION

Regional Setting

The South Cuyama oil field is located approximately 45 miles west of Bakersfield, California in the Cuyama basin in the southern

Coast Ranges (Figures 1 and 2). The basin lies north of the west- trending Transverse Ranges and west of the Great Valley.

The Cuyama basin contains a sequence of middle and late

Cenozoic age which unconformably overlies and is superimposed on a

Late Cretaceous to early Tertiary sedimentary succession (Figure 3).

The Cuyama basin is part of the Salinian block, a region between

the San Andreas and Rinconada faults which is characterized by

granitic or gneissic basement. East of the San Andreas fault and west of the Rinconada fault non-granitic Franciscan Formation com-

prises the "basement." There is no direct evidence for the nature

of the basement beneath the Cuyama basin. However, in the La Panza

Range northwest of the Cuyama basin, Late Cretaceous strata are

underlain by a Mesozoic granitic terrane (Ross, 1978). Furthermore,

the Barrett Ridge area north of the Cuyama basin and the Mount Abel

area east of the basin are characterized by a gneissic terrane at

least in part of Precambrian age (Ross, 1978; Kistler, 1978). The

granitic and gneissic terranes are separated by the north-northwest- 2

Figure 1. Index map.

42°

38° O -.6 0 be. 0

0 o- 0

(3. Figure 2 ee.\/Figure 3 f 11\ Bakersfield \ a Cs* -t ,scp,t\O Mojave \ Desert CO I B1 PoNe*\\.// 0/1 CMICI 60 34°N Transverse Little a Los Son Bernardino 411 Angeles Mountains

O 100 200 300 Km

O 100 200 Mi

1124° 1120° 1116°W 120° \ 119°

35°

C.) GREA 0 V A t.1 E

RAZIER SAN GABRIEL Frkklk,.. M TN

SAN RANGE T ABEL ANDREA MT PINOS 1... FO RILLILLSLS FAULT SO -.1

/44s CPARR..120 .:( ...------c _. A .:4 LAKE L A IN 4. vkokt.... sit).\ ..V 10,.t toS S ,4 Cif:00' )./e/4 i F LT. 119° 81:1-IIME:EAlsEHT); F'''''"'".4-----1--'--':..T.:.'" c,°. :)0c,,,i44)CHILItt.411-:" ---1.--;.;4,:"13:1:EL,t'ASC:(:1% R1.10,5SELLnNCNRtp4l 4.. RANGE SOUTH CUYAMA f L''' Figure 2. Tectonic Map of LA PANZA A 4 AC)REMING CUYAP, FLT. f,GE 0N..1 ADA S ERR the Cuyama Basin. SUR- NACI M IENTO FAULT VO.0

SANTA LUCIARANGE SAN RAFAELMTNS Strike-slip faultReverse fault 121° Dotted where covered

SCALE CALIFORNIA

0 10 20 /On Anticline 0C292179aNitSiT110 20 1,A \-%

35° Drafting by Edwin R Howes 120°

0.1 Figure 3. Generalized Regional Geologic Map of the Cuyama Basin Area. (Modified from Jennings and Strand, 1969; Smith, 1964; and Jennings 1958 59.)

Reverse fault, dotted where OM concealed Recent alluvial deposits

0 Os Strike-slip fault, Nonmarine deposits, surface dotted where Preserved; Pleistoceneage. concealed ° Nonmarine deposits, deformed; Pliocene and Pleistocene age. 35.00

Oat Sedimentary rocks of Miocene age, local igneous flows and intrusions

'New CuyOrn; Mm, marine AV, -Branch Canyon Mc, nonmarine South w.k Mb, basalt sill Cuyama o//ey Oil Field 0 c Santa Barbara Nonmarine sedimentary rocks of anyon Oligoceneage. ,En% Marine sedimentary racks of Eocene and Paleocene age 0 0 15 Marine sedimentary rocks oflate 6-Cretaceous age.

o Gneissic Rock 0

-At 5

trending San Juan-Chimenas fault which may join the San Andreas

fault north of Red Hills. The subsurface Russell fault may be

the southern extension of the San Juan-Chimeneas fault (Schwade

and others, 1958; Bartow, 1974). The origin and tectonic emplace-

ment of the granitic Salinian block west of the "Franciscan"

rocks of the Great Valley is a controversial topic (cf. Ross,

1978; Kistler, 1978; Page, 1981).

The present-day Cuyama Valley trends slightly north of west,

almost a Transverse Range trend, cutting across older northwest-

oriented structures. The valley is bounded on the north by the

Caliente Range which has been thrust southward along the north-dip-

ping Whiterock and Morales faults. The Sierra Madre Mountains have

been thrust northward on the south-dipping South Cuyama and Ozena

faults. These thrust faults tectonically overlie the older northwest-

trending Russell fault.

The Cuyama Valley contains two large oil fields: the South

Cuyama and Russell Ranch oil fields (Figures 2 and 3). The South

Cuyama oil field is the major focus of the study (Figure 3; Plates

I and II).

Objectives

The purpose of this study was to map in detail the subsurface geology of the area outlined in Plate I and to integrate this subsurface geology with surface geology. The emphasis of the subsurface mapping is on tectonic style and structural age relations. 6

The results of the study are used to integratethe geologic history of this well-documented area with the regionalhistory of the southern

Salinian block and the San Andreas fault.

A related study conducted by Barbara B. Nevins(1982) at Oregon

State University examines the Russell Ranchoil field. These studies

are part of a larger project, underthe direction of Dr. Robert S.

Yeats, with the major goal of determining therelation between the

major thrust faults of Cuyama basin and the right-lateral SanAndreas

fault.

Methods

The study area contains 330 oil wells drilled inand adjacent

to the South Cuyama oil field(Plates I and II). Well data include

electric logs, dipmeter logs, directional surveys, core,sidewall

and ditch sample descriptions, and paleontologicalreports. With

the subsurface data, 70 cross sections wereconstructed, of which

six appear in this report (Plates I andII). Structure contour

maps of key horizons and isopach maps wereconstructed. Detailed

subsurface mapping in the oil field indicatesthat dip values from

dipmeter reports are consistently too steep;therefore, the true

stratigraphic thickness of an interval to beisopached was deter-

mined by measuring the thickness of theinterval on the constructed

cross sections.

The detailed geologic mapping of the areaby Vedder and Repenning

(1975) was used for surface control (PlateIII). Field work consisted 7 of familiarizing myself with the rocks in surface exposure, including lithology, contacts, facies relations, and structural style to aid in subsurface mapping.

Previous Work

The earliest attempts to produce comprehensive geological reports on the Cuyama Valley area were by English (1916) and Eaton and others (1941). Following the discovery of oil in Cuyama Valley,

Hill and others (1958) published a description of the stratigraphy of the study area. A companion study by Schwade and others (1958) concentrates on the regional geology, including subsurface geology.

A short report on the geology of the South Cuyama oil field was published by Zulberti (1954).

Dibblee (1973a) produced a regional geologic map of the Cuyama basin and adjacent areas. The U.S. Geological Survey published detailed geological maps of the study area on a 7 1/2 minute quadrangle base (Vedder, 1970; Vedder and Repenning, 1975).

Important sedimentological studies include Bartow (1974, 1978) on the Simmler and Vaqueros Formations, Clifton (1968, 1981) on the

Branch Canyon Sandstone, Fritsche (1969) on the Miocene sedimentary rocks of the Sierra Madre Mountains, and Chipping (1970) on the

Paleogene of the Sierra Madre Mountains.

Important biostratigraphic studies include Repenning and Vedder

(1961) and Vedder (1973) on the Miocene rocks of the Caliente Range,

Fritsche (1969) on mollusks of the Sierra Madre Mountains and Phillips 8

(1976) and Lagoe (1981, 1982) on the Monterey Formation.

Dibblee (1973b) discussed the regional stratigraphy of the

Cuyama basin and adjacent areas. Upson and Worts (1951) published a groundwater report on the Cuyama Valley. 9

STRATIGRAPHY

General Statement

The crystalline basement terranes of the Salinian block are overlain by strata of Late Cretaceous to Holocene age. Figure 4 is a generalized stratigraphic diagram of the Cuyama basin, and Plate V is a type electric log for the South Cuyama oil field. A north-south straight-line stratigraphic correlation chart (Plate IV) indicates that large differences in thickness and stratigraphic sequence occur across major faults in the Cuyama Valley area.

Crystalline basement is not encountered in the study area.

Effective "basement" is a Late Cretaceous and/or early Tertiary succession of marine sedimentary rocks which presumably overlies crystalline rocks at depth. The nonmarine Simmler Formation of

Oligocene age lies unconformably on older marine strata in the

Cuyama basin, northeast and west of the study area. Conformably above the Simmier Formation lies the marine Vaqueros Formation of late Oligocene to early Miocene age. The Vaqueros Formation is overlain conformably by the early Miocene marine Monterey For- mation, which is itself conformably overlain by and in part lateral-

ly gradational into the Branch Canyon Sandstone in the study area.

The marine Santa Margarita Formation conformably overlies the Branch

Canyon Sandstone and is probably of middle to late Miocene age.

East and northeast of the study area, the Oligocene-Miocene marine

sequence grades laterally eastward into the nonmarine Caliente Figure . Generalized stratigraphy of the Cuyama Basin (from Lagoe, 1982).

M1.1.. NoRTHWEST CALIENTE 6 CENTRAL AND SOUTHEAST EPIN3I/ FORAM. CUYAMA VALLEY SIERRA MADRE RANGE SERIES STAGES STAGES IA PANZA RANCES CALIENTE RANCE k.

POST- PLIOCENE PASO RORLES FM. 'MALES FM. MORALES FM. MORALES FM. Ho IINIAN

-,...... ,..-...... -.-....--'.,/-s- w "JACA- LITos" 13 - - - WHIM SANTA MARGARITA EH. SANTA SANTA SANTA "MAMA- / / MARGARITA MARGARITA / MARGARITA / RITAN" / FM. FM. / FM. / .

&a J W 0...1 MONTEREY BRANCH MONTEREY 0LUISIAN . nI . z oz CANYON z . FORMATION .0 z x. SANDSTONE p.. la "TEA- z 0 2 li a 1 101 0 (..,I-. 0W , 4. In u bum" LI k 2 x n KELIZIAN 0 u ? 0 z . MoNTERET 0 g.. u w 33 5 e W . VAQUEROS 3 $, FM. 2 E ii 6 FORMATION z SAUC------1 8 8 ES IAN - - _ - - VAQUEROS VAQUEROS VAQUEROS "YAW- FORMATION FORMATION FORMATION

EROS" oLIG0- ZEH0R- SimmLER FM.

GENE RIAN SIHHLER FM. SIMMER FM. SIMMER. FM.

PRE- tRETAGEMIS- CRETACEOUS- CRETACEOUS- PAIYANAHE CRYSTAL- ZENIOR- CRYSTALLINE ROCKS PALEOCENE PALEOGENE ROCKS LINE ROCKS ROCKS RIAN ROCKS 11

Formation. The Miocene marine strata are overlain unconformably by Pliocene and Pleistocene nonmarine deposits, including the

Morales Formation and younger alluvial deposits of the Cuyama

River.

Unnamed Pre-Oligocene Marine Sedimentary Rocks

Unnamed pre-Oligocene marine sedimentary rocks unconformably underlie the late Oligocene to early Miocene Vaqueros Formation in the study area north of the Russell fault. Wells drilled into the tectonic block southwest of the Russell fault and beneath the

South Cuyama fault were not deep enough to determine if pre-Oligocene marine strata are present there. The thickness of the pre-Oligocene sequence is unknown in the study area. The South Cuyama Unit 52-1 well penetrated 690 feet of pre-Oligocene marine strata without reaching the base of the sequence. Cores indicatethat the strata are composed of interbedded sandstone and siltstone. The sandstone is gray to dark gray, fine- to medium-grained, and tightly cemented.

The siltstone is black to dark gray, hard, massive, and brittle.

Both rock types contain abundant carbonaceous matter. Most oil reports refer to this sequence as the "Cretaceous" of Cuyama Valley.

Hill and others (1958) stated that a few well sections contain

Siphogenerinoides whitei, a foram diagnostic of the Late Cretaceous.

However, Hill and others do not specify which wells in Cuyama Valley contain this fauna. In the study area, well data indicate that fos-

sils are extremely rare and are not diagnostic of age. Dipmeter and 12 core dips indicate the contact with overlying strata is an angular unconformity.

Pre-Oligocene marine sedimentary rocks are exposed in the cores of en echelon domes in the southeastern Caliente Range and over large areas of the Sierra Madre Mountains (Figure 3), where locally they are overlain by nonmarine Simmler Formation which itself underlies the Vaqueros. Chipping (1970, 1972) determined that most of these strata in the Sierra Madre Mountains are early Tertiary in age and were deposited by turbidity currents. Hill and others (1958) named the sequence in the southeastern Caliente Range the Pattiway Formation.

Vedder and Repenning (1975) assigned a Paleocene age to the Pattiway

Formation, and Sage (1973) concluded the Pattiway Formation was deposited within a submarine fan or delta environment.

It is not possible to correlate the pre-Oligocene marine strata beneath Cuyama Valley in the study area to either the Pattiway

Formation or to the Late Cretaceous to early Tertiary sequence in the Sierra Madre Mountains due to poor age control in the subsurface and to the presence of major faults between the subsurface and outcrop sections.

Simmler Formation

The Simmler Formation was named by Hill and others (1958) for a nonmarine sequence, 3,000 feet thick, that overlies the Pattiway

Formation in the southeastern Caliente Range. In the Cuyama Gorge area and southeastern Caliente Range, the Simmler Formation lies 13 unconformably on and overlaps the upper Cretaceous to lower Terti- ary marine sedimentary sequence and is overlain conformably by the

Vaqueros Formation. Within the study area, the Arco Fisher 1 well encounters the only nonmarine strata possibly correlative to the

Simmler Formation.

At the type area the Simmler Formation consists of red and greenish gray sandstone with interbeds of maroon and green siltstone. The Arco Fisher 1 well penetrated approximately 45 feet of dark brown to red sandy claystone and red, coarse-grained, angular, argillaceous sandstone underlying the Vaqueros Formation; the base of the variegated sequence was not reached.

The Simmler Formation consists of a sandstone facies and a conglomerate facies (Bartow, 1974; 1978). The sandstone facies appears to be restricted to areas northeast of the Big Spring and Morales thrust faults, and the conglomerate facies is found southwest of these faults. As noted by Bartow (1974, 1978), ter- restrial redbeds in Santa Barbara Canyon are similar in lithology and stratigraphic position to the conglomerate facies of the

Simmler Formation. The beds were originally called the Pato Red

Member of the Vaqueros Formation by English (1916), and the Caliente

Formation by Hill and others (1958) and Vedder (1968). The redbeds in Santa Barbara Canyon may be correlative to the Simmler Formation encountered in the Arco Fisher 1 well; both underlie the marine

Vaqueros Formation. Dibblee (1973a) mapped a small exposure of

Simmler Formation in the central Sierra Madre Mountains underlying 14 the Vaqueros Formation.

Because the Simmler Formation is unfossiliferous, its Oligocene age assignment is based on its stratigraphic position unconformably overlying marine strata as young as Eocene and conformably underlying marine strata as old as Oligocene.

Vaqueros Formation

Eaton and others (1941) mapped middle Tertiary marine sandstone, siltstone, and shale in the Caliente Range as "Vaqueros" and lower "Temblor." They differentiated the two formations on the basis of faunal content even though they arelithologically inseparable. Hill and others (1958) renamed these strata the

Vaqueros Formation, with three members in the Cuyama basin. In ascending order, the members are the Soda Lake Sandstone Member,

Soda Lake Shale Member, and the Painted Rock Sandstone Member.

Dibblee (1973b) renamed the basal sandstone the Quail Canyon

Sandstone Member.

In the Cuyama basin, the Vaqueros Formation lies conformably on the Simmler Formation. Where the Simmler Formation is not present, the Vaqueros Formation lies with angular unconformity on the Late

Cretaceous-early Tertiary marine sequence. In the Caliente Range, the Vaqueros Formation is 7,000 feet thick. South of the Morales fault on the north side of the Cuyama Valley, the Vaqueros Forma- tion is only 900 feet thick (Plate VI). The formation thickens to the

south-southwest to 1,800 feet in the center of the valley north 15 of the South Cuyama oil field, and thins to less than 450 feet in the oil field itself (Plates VI and VII). In the southeastern

Sierra Madre Mountains, the Vaqueros Formation varies from 0 to 800 feet thick (Fritsche 1969).

Quail Canyon Sandstone Member. At the type locality in the southeastern Caliente Range, the Quail Canyon Sandstone Member consists of 300 feet of fine- to medium-grained well-sorted massive sandstone (Hill and others, 1958; Bartow, 1974). The member is gradational upward and laterally westward into the Soda Lake Shale

Member.

In the subsurface of the study area, the Quail Canyon Sandstone

Member varies in thickness from 0 to over 100 feet. Thickness variations in the member appear to be related to pre-Vaqueros topography (Plate VII). The member is composed of gray, fine- to medium-grained calcareous sandstone. Megafossil fragments and thin fossil "reefs" were found in several cores. The Quail

Canyon Sandstone Member is a productive oil sand at the crest of the South Cuyama dome where it is called the "Colgrove sand" or

"Hibberd zone."

The Quail Canyon Sandstone Member contains a sparse molluscan fauna diagnostic of the Vaqueros Stage (provincial early to middle

Miocene) in the Caliente Range (Dibblee, 1973b; Vedder and Repenning,

1975). In the Caliente Range, the member lies conformably below siltstone containing a Zemorrian foraminiferal fauna of Oligocene to early Miocene age and conformably above the nonmarine, unfossilifer- 16 ous Simmler Formation. Where the Simmler Formation is absent, the Quail Canyon Sandstone lies unconformably on the Late Cretaceous to early Tertiary marine sequence. The Quail Canyon Sandstone Mem- ber is of late Oligocene age as based upon foraminifera in the overlying siltstone.

Bartow (1974) interpreted the Quail Canyon Sandstone Member to be a basal transgressive sand, probably deposited in a variety of high-energy shallow marine environments.

Soda Lake Shale Member. The Soda Lake Shale Member is 1,200 feet thick at the type locality near Soda Lake in the Carrizo

Plain (Hill and others, 1958). In the type area, the Soda Lake

Shale Member is composed of dark gray to black siltstone and platy shale with thin sandstone interbeds (Bartow, 1974). In the southeastern Caliente Range, the Soda Lake Shale Member is approximately 2,000 feet thick (Bartow, 1974). The upper part of the Soda Lake Shale Member contains turbidite sandstone, and the contact with the overlying Painted Rock Sandstone Member is gradational.

In the study area, the Soda Lake Shale Member varies in thickness from 100 to 800 feet. The thickest section occurs in the center of the Cuyama Valley north of the South Cuyama oil field (Plate

VII and VIII). The member thins to the south over the South Cuyama dome by onlapping older Soda Lake strata and by actual thinning of the member (Plate VII), indicating early growth of the South Cuyama dome during deposition of the Soda Lake Shale. The member also thins 17 toward the north side of the valley, however, it is not possible to determine the mechanism of thinning on the north side of the valley

(Plate VII). Cores from the Soda Lake Shale Member consist of dark gray to black, massive siltstone. The member is locally calcareous and contains foraminifera and fish remains. The member contains sandstone interbeds, especially in the upper part, which are probably turbidites. The contact with the overlying Painted Rcck

Sandstone Member is gradational. Locally the subsurface Soda Lake

Shale Member is called the "Colgrove Shale".

In the southeastern Caliente Range, the lower part of the Soda

Lake Shale Member contains a Zemorrian foraminiferal fauna, now interpreted as late Oligocene (Poore, 1981). The remainder of the member, up to the base of the Painted Rock Sandstone Member, contains a foraminiferal fauna diagnostic of the early Miocene Saucesian Stage

(Vedder and Repenning, 1975). The lowest part of the member in the

Cuyama Valley oil fields contains a Zemorrian Stage fauna and the upper part a Saucesian Stage fauna, according to R. L. Pierce(in

Dibblee, 1973b). Very little paleoecologic or paleoenvironmental work has been done on the Soda Lake Shale Member. Bartow (1974) suggested that the member is a basinal deposit with turbidite interbeds, and the upper part of the Soda Lake Shale Member represents a shallowing upwards cycle of deposition.

Painted Rock Sandstone Member. The Painted Rock Sandstone

Member was named after Painted Rock, a sandstone outcrop in the northwestern Caliente Range with Chumash Indian pictographs (Cawley, 18

1962). Hill and others (1958) designated the excellent exposures on the southeastern flank of Caliente Mountain as the type locality.

Eaton and others (1941) previously mapped the lower portion of the

Painted Rock Sandstone Member as "Vaqueros" and included the upper portion in their "Temblor."

The Painted Rock Sandstone Member is 5,400 feet thick at the type locality and thins southeastward to less than 500 feet in the southeastern Caliente Range. In the study area beneath Cuyama

Valley, the member varies in thickness from less than 300 feet tc,

850 feet. The Painted Rock Sandstone is more than five times thicker on the north side of the Morales fault than it is on the south side

(Plate IV). The Painted Rock Sandstone Member is not present in the

Sierra Madre Range portion of the study area.

At the type locality, the Painted Rock Sandstone is composed predominantly of thick-bedded, medium-grained, arkosic sandstone.

The lower part of the member contains a large proportion of siltstone. Sandstone interbeds in the lowermost few hundred feet of the member are probably turbidite deposits (Bartow, 1974) similar to sandstone in the Soda Lake Shale. The upper part of the Painted Rock Sand- stone is locally fossiliferous.

The Painted Rock Sandstone Member is the main producing zone in the South Cuyama oil field, where it is known as the "Dibblee sand" or the "Dibblee zone" by the petroleum industry. Within the oil field, the Painted Rock Sandstone Member is subdivided into several subzones (Zu2berti, 1954). Cores indicate the lower part of 19

the member is composed of gray, fine-grained,massive, silty sand-

stone with sandy siltstone interbeds. The upper part of the member

consists of gray, fine- to medium-grained, silty sandstonewith

common fossil "reefs." The upper contact with the overlying Monterey

Formation becomes stratigraphically higher towards thenorth in the

study area (Plates VII and VIII).

A Vaqueros Stage (provincial early Miocene) marine fauna is

found in the Painted Rock Sandstone Member (Repenning andVedder,

1961). The uppermost part of the member contains Temblor Stage

(provincial early-middle Miocene) molluscs (Dibblee, 1973b). Sau-

cesian Stage foraminifera occur in siltstones thatunderlie and

overlie the member in the subsurface and at the surface (Dibblee,

1973b). In the northwestern Caliente Range, the overlyingMonterey

Formation is Relizian (Lagoe, 1982). Bartow (1974) intepreted

the Painted Rock Sandstone Member in the central CalienteRange

as a marine shelf deposit which probably received sediment from

prograding Painted Rock Sandstone deltas to the northwest and

southeast.

Monterey Formation

In the Cuyama Valley, strata mapped as Monterey Formationwere

referred to the Maricopa Shale and the Whiterock Bluff shalemember

of the Santa Margarita Formation by English (1916). Eaton and others (1958) mapped these strata as theupper part of the "Temblor."

Hill and others (1958) correlated these stratato the Monterey 20

Formation, which they subdivided into two members, the Saltos Shale

Member and the overlying Whiterock Bluff Shale Member.

Saltos Shale Member. The Saltos Shale Member is best exposed on the southwest slopes of the Caliente Range. Hill and others

(1958) designated the type section in an unnamed canyon on Caliente

Mountain. The Saltos Shale Member also occurs in the subsurface of

the Cuyama Valley and is exposed in the Sierra Madre Mountains.

In the Caliente Range, the Saltos Shale Member consists of up to 2,100 feet of siliceous claystone and siltstone with thin beds of impure limestone and dolomite. Abundant foraminifera and

fish remains are characteristic. The Saltos Shale lies conformably

on the Vaqueros Formation and grades upward into the WhiterockBluff

Shale Member (Phillips, 1976). On the northeast flank of the

Caliente Range, the Saltos Shale Member interfingers with the

Branch Canyon Sandstone to the east (Clifton, 1981).

In the study area beneath Cuyama Valley, the Saltos Shale Mem-

ber varies in thickness from 1,000 feet on the north side of the

valley to less than 100 feet in the South Cuyama oil field (Plate

IX). Here it consists of dark brown to dark gray laminated silt-

stone and claystone with thin beds of medium-grainedsilty-sand-

stone. Foraminifera and fish remains are abundant in cores and

ditch samples.

Fritsche (1969) mapped a calcareous clayey shale and claystone

in the Sierra Madre Mountains as the Saltos Shale Member of the

Monterey Formation. In the upper plate of the South Cuyama thrust, 21

Vedder and Repenning (1975) mapped a sequence which they called an informal lower unit of the Monterey Formation; they suggested that this unit may be correlative with the Saltos Shale Member. Their lower Monterey unit is approximately 700 feet thick and grades upwards into the Branch Canyon Sandstone.

The lower part of the Saltos Shale Member contains foraminifera characteristic of the Saucesian Stage (early Miocene), and the upper part contains foraminifera of the Relizian Stage (late early Miocene)

(Lagoe, 1981; 1982). In the subsurface study area, Lagoe (1981; 1982) interprets the Saucesian portion of the Saltos Shale Member to be a base of slope or basin-floor deposit which accumulated at middle bathyal depths (1,560-6,250 feet; 500-2,000 meters). The upper part was deposited at upper bathyal depths (470-1,560 feet; 150-500 meters) as shelf-edge deposits.

Whiterock Bluff Shale Member. The Whiterock Bluff Shale Member was named after exposures at Whiterock Bluff, northwest of the study area, by English (1916) and Hill and others (1958). The member is composed of a white-weathering biogenetic siliceous shale with Relizian and Luisian microfossils (Phillips, 1976). The member is not found in the South Cuyama study area, where beds of the same age are mapped as

Branch Canyon Sandstone. Vedder and Repenning (1975) mapped a tongue of siliceous siltstone within the Branch Canyon Sandstone in the Sierra

Madre Mountains as an informal upper unit of the Monterey Formation.

They reported that the siltstone contains a Luisian foraminifera fauna and may be correlative with the Whiterock Bluff Shale Member. 22

Branch Canyon Sandstone

The rocks of the Branch Canyon Sandstone were mapped as lower

"Neroly," "Cierbo," "Briones," "Temblor," and "Vaqueros" by Eaton

and others (1941) based on the faunal content of the rocks rather

than lithology. Hill and others (1958) renamed these strata the

Branch Canyon Formation with the type section at Branch Canyon,

south of the South Cuyama oil field (Plate III). Dibblee (1973b)

changed the name to Branch Canyon Sandstone. The Branch Canyon

Sandstone is also found in the subsurface of Cuyama Valley and

in surface exposures in the Caliente Range.

At the type locality, the Branch Canyon Sandstone unconformably

overlies pre-Oligocene marine sedimentary rocks and is 3,200 feet

thick. Vedder and Repenning (1975) mapped four informal units in

the Branch Canyon Sandstone. These units have not been correlated

to the Branch Canyon Sandstone in the subsurface. The Branch Canyon

Sandstone is predominantly a gray, thick-bedded to massive, fine-

to coarse-grained sandstone. The upper part contains many calcareous

"reefs." The upper contact of the Branch Canyon Sandstone at the

type locality was mapped at the base of a phosphatic claystone which Hill and others (1958) assigned to the Santa Margarita

Formation. To the east, where the basal claystone of the Santa

Margarita Formation pinches out, the Branch Canyon Sandstone is

overlain by lithologically similar sandstone of the Santa Margarita

Formation (Fritsche, 1969). Madsen (1959) stated that the greater 23 amount of shale and the presence of "reefs" composed almostentirely of Ostrea titan in the Santa Margarita Formation served to distinguish the sandstone members of the Santa Margarita Formation from the Branch Canyon Sandstone.

At the type section, the lower part of the Branch Canyon Sand- stone contains mollusks and echinoids diagnostic of the"Temblor

Stage", and the remainder contains a fauna diagnostic of the "Santa

Margarita Stage" (Dibblee, 1973). Siltstone from near the base of the formation contains Relizian Stage foraminifera (Hill and others,

1958). A tongue of the Monterey Formation in the upper part of the

Branch Canyon Sandstone, between Branch Canyon and Salisbury Canyon, contains Luisian foraminifera . The Branch Canyon Sandstone is late early to early late Miocene age.

In the South Cuyama oil field, the Saltos Shale Member of the

Monterey Formation is overlain by 400 to 700 feet of sandstone with a blocky electric log response (Plate V). Core samples from

this section consist of dark gray to gray, fine- to medium-grained massive sandstone. The underlying Monterey Formation contains

Relizian foraminifera, and overlying strata contain probable Luisian

foraminiferas. This subsurface section of sandstone is assigned to

the Branch Canyon Sandstone based on its massive character, strati-

graphic position, and probable early to middle Miocene age.

The "Johnston sand" of Zulberti (1951) is a tongue of gray,

fine- to medium-grained, silty sandstone in the upper Saltos Shale

Member on the southeast plunge of the South Cuyama dome. The sand- 24 stone is from 0 to 250 feet thick, lensing out in a west-northwest direction toward the crest of the dome (Figure 5; Plates X and XI).

The "Johnston sand" is considered to be an informal member of the

Branch Canyon Sandstone in this study for the following reasons:

1) it is overlain and underlain by Relizian Monterey Formation and is therefore probably the same age as the lower part of the Branch

Canyon Sandstone at the type locality, 2) it has an electric log response similar to that of the Branch Canyon Sandstone, and 3) the

Monterey interval between the Branch Canyon Sandstone and "Johnston sand" appears to decrease in thickness to the southeast by inter- tonguing with the Branch Canyon Sandstone.

Clifton (1981) interprets the Branch Canyon Sandstone in the

Caliente Range to represent deposition in a variety of shallow- marine environments, from shallow shelf to beach foreshore. He concludes that the marine to nonmarine facies change in the Caliente

Range is made up of numerous progradational sequences deposited during marine transgressive-regressive cycles. These cycles have not been recognized in the Sierra Madre Mountains (H. Clifton, 1982, person. commun.).

Santa Margarita Formation

Eaton and others (1941) mapped marine sandstone and claystone above the Branch Canyon Sandstone in the Sierra Madre Mountains as

"Neroly." Hill and others (1958) renamed these strata the Santa

Margarita Formation. Fritsche (1969) and Vedder and Repenning 25

IFigure 5.Isopach Map of the Johnston Sand.

Branch Canyon Ss '=2 Sa nos Shale

Cr 361. Johnston Sand 14;) Strike-slip Fault 23 24 s 53,3". 3 Salton Shale

17 Normal Fault

Painted Rock Ss

Contour Line, Interval 50 Ft. 30 25 27 South Cuyamo Oil Field

35 34

LOCATION MAP 4 444.,

.*(?(

7 "YOrna Valley 710 N SCALE 7 9 N 0 I 2 3 4 5000 Ft. South Cuyamo rAIMA FLT Oil Field iOs> 33 O 5 K m 11,,o T$Nr= cex < 2. O 5M, 26

(1975) divided Miocene strata above the Branch Canyon Sandstone near Branch Canyon into five lithologic units. The uppermost unit

is in part nonmarine and lies unconformably on the underlying marine unit, leading Vedder and Repenning (1975) to tentatively assign the nonmarine unit to the Caliente Formation. Dibblee (1973a) mapped

the nonmarine member as the Quatal Formation. This report follows

Fritsche (1969) and includes the nonmarine unit in the Santa Margarita

Formation with the four underlying marine units.

The Santa Margarita Formation is exposed in the complexly fold-

ed upper plate of the South Cuyama fault. The thickness of the for-

mation varies, probably due to intense folding. The marine portion

of the Santa Margarita Formation is approximately 1,400 feet thick,

and the overlying nonmarine unit is at least 500 feet thick with

the top eroded away. In the Caliente Range, near Morales Canyon,

the Santa Margarita Formation is 1,400 feet thick.

The lowermost unit of the Santa Margarita Formation consists

of approximately 300 feet of siliceous claystone and shale. Phos-

phate pellets and nodular phosphatic zones distinguish Santa Margarita

claystone from the Monterey Formation (Fritsche, 1969). The basal

claystone is overlain with local unconformity by 300 to 800 feet of

poorly sorted, clayey sandstone. This lower sandstone unit is over-

lain by about 500 feet of siliceous claystone and siltstone.

This unit is itself overlain conformably by 350 feet of sandstone

lithologically similar to the lower sandstone. The upper sand-

stone is unconformably overlain by the nonmarine unit, which 27 consists of pinkish white, fine- to coarse-grained sandstone.

Where the basal claystone pinches out to the east, the contact between the lower Santa Margarita sandstone and Branch Canyon Sand- stone is impossible to locate on the basis of lithology (Fritsche,

1969). The upper part of the Branch Canyon Sandstone and the Santa

Margarita Formation contain "Santa Margarita" (late Miocene) mollusks and echinoids (Vedder and Repenning, 1975; Dibblee, 1973b).

Madsen (1959) distinguished sandstone of the Santa Margarita Forma- tion from the Branch Canyon Sandstone based on the whiter color, less resistance to weathering, and resulting lower relief of the

Santa Margarita Formation. Madsen (1959) and Fritsche (1969) noted that the Santa Margarita Formation contains mostly oysters and scallops and the upper Branch Canyon Sandstone contains mostly echinoids. The Santa Margarita Formation is correlated to subsurface sections only in the hanging-wall block of the South Cuyama thrust

(Plates X, XII, XIII, and XIV). The sequence of Santa Margarita lithologies could not be correlated to the footwall block of the

South Cuyama fault or to the section northeast of the Russell fault

(see section on Branch Canyon Sandstone-Santa Margarita Formation undifferentiated). Where the distinctive claystone units of the

Santa Margarita Formation are absent and paleontological control is lacking, it is not possible to differentiate the Branch Canyon Sand- stone and Santa Margarita Formation.

The marine Santa Margarita Formation contains late Miocene mollusks, shallow marine foraminifera, and Mohnian Stage fish scales 28 in the basal claystone (Vedder and Repenning, 1975). The Santa

Margarita was probably deposited as a littoral marine facies of a regressing sea (Dibblee, 1973b).

Branch Canyon Sandstone-Santa Margarita Formation Undifferentiated

In the South Cuyama oil field, the Branch Canyon Sandstone is overlain by approximately 1,200 feet of marine sandstone and interbedded siltstone. The great amount of fine grained material in this section results in a jagged electric log response compared to the blocky response of the Branch Canyon Sandstone (Plate V). Cores from this marine sequence yield only undiagnostic shallow-marine fauna. The lack of paleontologic age control and the absence of distinctive lithologies prevent the correlation of these strata to either the Branch Canyon Sandstone or to the Santa Margarita Forma- tion. In this report, these beds are called the Branch Canyon Sand- stone-Santa Margarita Formation undifferentiated.

The Branch Canyon Sandstone-Santa Margarita Formation undifferentiated consists of light to dark green-gray, fine- to medium- grained sandstone with interbeds of green-gray siltstone. Electric log correlation of markers in this section is tenuous and relatively unreliable. Markers can be correlated only a short distance, whereas

Branch Canyon Sandstone markers can be correlated across the entire study area. The sequence is thicker on the downthrown sides of some faults in the South Cuyama oil field (Figure 6).

The Arco Fisher 1 well penetrated 4,300 feet of marine sand- 29 stone and interbedded siltstone overlying the Monterey Formation southwest of the Russell fault and beneath the South Cuyama fault.

The lower 3,000 feet of this section consist of interbedded gray silty sandstone and dark brown sandy siltstone which contains a fauna of probable Relizian or Luisian age. The upper part consists of a massive light gray brown sandstone which contains abundant

"Santa Margarita" shallow water forams. This massive sequence cannot be correlated to strata northeast of the Russell Fault or to strata in the upper plate of the South Cuyama fault. These rocks are also included in the Branch Canyon Sandstone-Santa

Margarita Formation undifferentiated.

Morales(?) Formation

The name "Morales" was first used by English (1916) for nonmarine strata exposed in Morales Canyon, several miles northwest of the study area. Hill and others (1958) formally defined the Morales

Formation and designated a type locality for exposures several miles east of Morales Canyon. At the type locality, the Morales

Formation consists of approximately 2,700 feet of nonmarine claystone, sandstone, and gravel lying with angular unconformity on the Santa Margarita Formation.

The Morales Formation has not been correlated unequivocally to the south side of Cuyama Valley. Hill and others (1958) and

Dibblee (1973a) described a nonmarine sequence on the south side of Cuyama Valley as the Morales Formation. Most of these strata 30

Figure 6. Isopach Map of the Branch Canyon Sandstone - Santa Margarita Formation, Undifferentiated. Composite Type E-tog for tne _r South Cuyamo Oil Ffeld(PlateY) Morales(?) Formc,on Strike-slip Fault

't Branch Canyon Sandstone 24 Santo Margarita Format ) Undifferentiate: Normal Fault 32

Branch Canyon Sandsto,.s --6--____ Contour Line , Interval 100 Ft.

30 South Cuyamo Oil Field

32 34

5 2

I LOCATION MAP 4,0

'144-e

7 `"YOrry, tA Volley 7 10 N SCALE 7 9 N 0 I 2 3 4 5000 Ft South Cuyoma 'AMA FLT Oil Field O 3 0 5 Km

0 5 Mi 31 were previously mapped as the Cuyama Formation by English (1916) and as Pleistocene fans by Eaton and others (1941), both of these units overlie the Morales Formation at its type locality. Vedder and Repen- ning (1975) mapped these strata as deformed alluvium, although they also mapped several small exposures which lie underneath the deformed alluvium as questionable Morales Formation. They also mapped several fault slivers of Morales Formation in the South Cuyama faultzone

(Plate III). Strata assigned to the Morales Formation in the South

Cuyama oil field by Zulberti (1951) overlie the Branch Canyon

Sandstone-Santa Margarita Formation undifferentiated conformably and cannot be correlated to surface exposures of the Morales Formation.

Because of these problems, we refer to the sequence overlying the

Branch Canyon Sandstone-Santa Margarita Formation undifferentiated in the subsurface of the Cuyama Valley as Morales(?) Formation.

In the South Cuyama oil field, the Morales(?) Formation is approximately 2,000 feet thick, increasing northeastward tomore than 5,000 feet. In the oil field, the Morales(?) Formation consists of a basal green claystone overlain by gray sandstone and siltstone, which grades upwards to buff sandstone and siltstone.

The claystone thickens towards the south and interfingers with the underlying Branch Canyon Sandstone-Santa Margarita Formation undifferentiated (Figure 7). In the northeastern part of the study area the Morales(?) Formation contains a large proportion of red-brown claystone and siltstone. The Morales(?) Formation has been correlated in the subsurface to wells drilled southwest 32 of the Russell Fault (Plates XII and XIII).

The Bell Petroleum Buzzard 1, South Cuyama Unit 81-35, Arco

Fisher 1 and Arco Elliott 88-34 wells sampled the Morales(?) Forma- tion and indicate that the lower part contains a shallow marine fauna. Probable equivalent strata on the northeast flank of the

Caliente Range and in Santa Barbara Canyon contain a redeposited shallow marine fauna (Vedder, 1968, 1970). It is possible that the marine fossils in the subsurface Morales(?) Formation are also redeposited. Alternatively, the absence of an unconformable lower contact would allow the possibility that the lower part of the Morales(?) Formation in the South Cuyama area is marine, and the sequence grades upwards to nonmarine deposits. If the lower part of the Morales(?) Formation is marine it should be assigned to the Santa Margarita Formation.

In the subsurface, the upper Morales(?) Formation cannot be distinguished from the overlying deformed alluvial deposits. In the South Cuyama oil field there is no evidence of discordance or change in lithology between the Morales(?) Formationand the deformed alluvium of Vedder and Repenning (1975). The deformed alluvium may be part of the Marales(?) Formation. In the southeast end of the Russell Ranch oil field Nevins (1982) mapped an angular unconformity within the Morales(?) Formation as described in this report. This unconformity is located above electric log marker

MO (cf. Plate V) and cannot be found south of Sec. 13, 14, 15, and

16, T1ON, R271; (Plate VIII). 33

Figure 7.Isopach Map of the Basal Morales (?) Formation Claystone. Composite Type E-iog for tr,..t. ;2:1 South Cuyoma Oil Field (Note3E) Morales I?) Formanor Contour Line; Interval 25 Ft. NE, Basal Claystone of the 100 Ft. SW of Russell Fault Morales(?) Forimaylon ;-". 1 i 24

' Reverse Fault, Teeth on 'sal Branch Canyon Sanastone Hanging Wall, Dashed Where Uncertain --- .."11Try.v.r.fref Normal Fault, Teeth on Foot Wall 25 3c South Cuyamo Oil Field

T 10 N T 9 N

5 2

I LOCATION MAP' 410 .43 44E. . ..<(`kS LO

Volley

T 10 N SCALE T 9 N 0 I 2 3 4 5000 Ft South Cuyoma 44101 FLT Oil Field 0, 4 5 Km NN nAlli111O Cr CC 5M 34

The age of the Morales Formation has not been determined accurately. At its type locality, it unconformably overlies late

Miocene strata and is overlain by Pleistocene alluvial deposits.

The subsurface Morales(?) Formation conformably overlies probable middle to late Miocene strata and concordantly underlies Pleisto- cene alluvial deposits. The Morales(?) Formation is probably

Pliocene to Pleistocene in age, but it may be as old as late Miocene.

Alluvium

The alluvial deposits of Cuyama Valley are divided into three units by Vedder and Repenning (1975). A lower deformed alluvial deposit is overlain by older alluvium. The valley is presently being filled by younger alluvium.

The deformed alluvial deposits were mapped as the Cuyama Forma- tion by English (1916) and Morales Formation by Hill and others

(1958) and Dibblee (1973a). The deposits consist of semiconsolidated to consolidated sandstone, conglomerate, and mudstone. The lithology is variable; clasts were derived from exposed Eocene and Miocene rocks in the Sierra Madre Mountains. In the subsurface of Cuyama Valley, a lower contact with the underlying Morales(?)

Formation cannot be discerned. The deformed alluvium may be part of the upper Morales(?) Formation. In places in the South Cuyama oil field, the deformed alluvium increases in gravel content towards the South Cuyama fault (Plates XII and XIII). Near the South Cuyama fault, the deformed alluvium is faulted and folded, and beds are 35

overturned in places (Plate III). Deformed alluvium is probably of

Pleistocene age.

Older alluvium is composed of semiconsolidated clay, silt,

sand, and gravel. In places the older alluvium includes terraces, dissected alluvial fans and colluvial deposits. The older alluvium is slightly deformed and is most likely of late Pleistocene age.

In the central part of the valley, older alluvium is exposed in a series of en echelon easttrending tectonic ridges: the Turkey

Trap and Graveyard Ridges.

Younger alluvium consists of unconsolidated silt, sand, and gravel of the present streams. The bedload of the Cuyama River is characterized by clasts of crystalline rocks from the Mount Abel region to the east. In contrast, side streams such as Branch Canyon contain a bedload of clasts of sedimentary rocks from the Sierra Madre

Mountains to the south or the Caliente Range to the north. 36

STRUCTURE

General Statement

The major structures in the Cuyama Valley are shown in Figure

8. Within the study area, the Cuyama Valley is bounded by the south-dipping South Cuyama fault and north-dipping Morales fault.

The Russell fault is overridden by the South Cuyama fault and overlain by alluvial deposits, and so it is known only from the subsurface. The South Cuyama dome is a structural high enclosing the South Cuyama oil field. The dome is also overridden by the

South Cuyama fault and overlain by alluvial deposits such that it has no surface expression. In this report, the structural features in the study area are described in the order of their relative age, oldest first.

"Vaqueros" Structure

An isopach map of the interval from electric log marker 17 near the top of the Vaqueros Formation to the base of the Vaqueros is a structure contour map of the base of the Vaqueros Formation at the end of Vaqueros deposition (Plate VI). The map shows both pre-Vaqueros topography and deformation of the pre-Vaqueros surface during the time of deposition of the Vaqueros Formation.

An elongate west- to slightly west-northwest-trending trough received over 1,800 feet of Vaqueros Formation in the central part of the study area (Plates VI, VII, and VIII). The Vaqueros thins Figure 8. Tectonic Map

35°00

Reverse Fault

Strike-slip Fault

Anticline

.71 0 5 10 15 Km

5 10 Mi 0 Oil Field

120'00 Drafting by Edwin R Howes 1119.45' I119'1,-,' 38

to the south to approximately 400 feet on the southwest flank of

the South Cuyama dome. The Vaqueros Formation also thins northward

from the elongate trough to less than 1,000 feet near Highway 166.

A stratigraphic correlation section of the Vaqueros Formation using

electric log marker 17 as the datum, Plate VII, shows the structure

of the Vaqueros Formation at the end of Vaqueros deposition.

The Soda Lake Shale Member thins southward over the South

Cuyama dome by ponding in the lowest part of the trough, thereby

onlapping older Soda Lake Shale electric log markers and by actual

thinning of the member indicated by convergence of electric log

markers within the Soda Lake Shale. The Painted Rock Sandstone

Member also thins to the south by thinning of individual sand

bodies in the member. The Quail Canyon Sandstone does not show any

facies relation to the overlying Soda Lake Shale or consistent

thickness relationship with the structure, suggesting that subsidence

and growth of the structure occurred after deposition of the Quail

Canyon Sandstone, and the Soda Lake-Quail Canyon Sandstone contact

is an unconformity. It is not possible to determine whether the high

on the north side of the valley is a result of pre-Vaqueros topography

or of deformation during deposition of the Vaqueros Formation.

Electric log markers within the Soda Lake Shale cannot be correlated

to the thinner section on the northern high. The northern high is

similar stratigraphically to the thinnest Vaquerosover the South

Cuyama dome. Both sections have a basal Quail Canyon Sandstone Member which is overlain by a thin Soda Lake Shale Member and Painted Rock 39

Sandstone Member, suggesting the same sequence of events occurred in both areas.

Figure 9 illustrates the proposed development of "Vaqueros" structure. In diagram A the shallow marine Quail Canyon Sandstone was deposited on a beveled wave-cut shelfof low relief underlain by

Paleogene and older marine strata. The shelf with its cover of wave-abraded marine sand was downdropped abruptly, preserving the shallow marine sands and at the same time warping the shelfsurface into a west-northwest-trending trough. The shallow marine Quail

Canyon Sandstone was covered unconformably by deep marine SodaLake

Shale (Diagram B) which at the same time became thinner towardthe structural high to the south (Diagram C). This is similar to the rapid subsidence of the Vaqueros Formation duringdeposition of the deep water Rincon Formation in the Santa Barbara Embayment(Edwards,

1971; Ingle, 1980). The structure continued to grow during deposition of the Soda Lake Shale Member and the Painted RockSandstone Member, resulting in thinning of these members over the structuralhighs as

the trough filled (Diagram C).

Bartow (1974) noted that the Simmler Formationpinches out

against basement highs in the La Panza Range and BarrettRidge

area. He also observed that the Vaqueros overlaps theSimmler

and thins over the easement highs. Bartow's observations indicate

that these highs re ?resent pre-Vaqueros topography,but he was not

able to confirm if any growth occurred duringdeposition of the

Vaqueros. Nevins (1982) mapped two west-northwest-trending 40 Figure 9. Evolution of "Vaqueros" Structure. (diagrammatic)

S N

A) Tqc

Deposition of Quail Canyon sand (Tqc) on beveled shelf underlain by deformed Paleogene and/or older marine strata (Tu).

Ts! South Cuyama Dome Rapid subsidence of shelf into deep water , preserving the shallow-marine sand. Shelf surface is warped during subsidence resulting in hemipelagic silts and thin turbidites of the Soda Lake Shale (Tsl) ponding in low areas.

C) DTs 1

South Tqc Cuyama Dome Continued deposition of Soda Lake Shale(Tsl) and Painted Rock Sandstone(Tpr), filling in the basin. Accentuation of warped surface during deposition of Soda Lake Shale and Painted Rock Sandstone caused thinning of these formations across the highs, in addition to onlap. 41 troughs in the Vaqueros at the end of Vaqueros deposition in the Russell Ranch oil field. The Vaqueros appears to form a series of right-stepping en echelon submarine troughs and uplifts trending obliquely into the Russell fault. The right-stepping en echelon arrangement of the structures along the Russell fault is similar to the pattern of folding developed during the early stages of wrench faulting (Wilcox and others, 1973) and suggests that right slip on the Russell fault may have occurred during the time of

Vaqueros deposition.

Cox Faults

The Cox fault zone is a major structural feature which strikes north to north-northeast across the Cuyama basin. It is located less than one mile east of the South Cuyama oil field (Figure 8).

Lagoe (1981, 1982) indicates that the eastern side of the fault zone is downthrown, and the Saltos Shale Member of the Monterey

Formation is three to seven times thicker on the downthrown side of the fault zone than it is on the upthrown side. The greater accumulation of Saltos on the downthrown side indicates that the Cox fault zone was a set of growth faults during deposition of the Saltos

Shale Member. The underlying Painted Rock Sandstone Member of the

Vaqueros Formation shows no consistent changes of thickness or of facies with respect to the Cox fault zone, indicating movement post- dated deposition of the Painted Rock Sandstone Member.

Several faults in the southeastern part of the South Cuyama 42 dome have a displacement history and orientation similar to the

Cox fault zone farther east. These faults are considered to be part of the Cox fault set. Plates XV and XVI are structure contour maps of electric log marker 17 near the base of the Saltos Shale

Member (Plate V). These maps show the structure attributed to the Cox fault set. The Cox faults in the South Cuyama dome have normal separation, strike north-northeast, and dip 50°-70° to the east (Plate X). The Cox faults offset the Painted Rock Sandstone

Member and older strata equally and die out in the lower Saltos

Shale Member (Plates X and XI). The Relizian "Johnston sand" is not cut by the Cox faults. An isopach map of an interval in the

Saltos Shale Member (Plate IX) and cross section B-B' (Plate X) indicate that the Saltos Shale Member is thicker on the downthrown sides of the Cox faults. The Cox 13-5 fault is the largest

Cox fault in the study area, downdropping electric log marker 17 nearly 200 feet; the Saltos thickens across this fault by 100 to 200 feet. The Saltos Shale thickens nearly 300 feet across the combined Cox 43-6 and 25-6 faults. The Cox faults were thus active during deposition of the Saltos Shale Member but ceased activity prior to deposition of the "Johnston sand."

The isopach map of the interval in the Saltos Shale Member indicates the member thins over the South Cuyama dome (Plate IX).

The isopached interval is more than 700 feet thick in the center of the valley, and it thins irregularly over the dome to 100 to

200 feet along the crest and southwest flank of the dome. The 43 thinning over the South Cuyama dome indicates that the dome was a structural high during deposition of theSaltos Shale Member, as concluded earlier by Lagoe (1981, 1982).

Growth of the proto-South Cuyama dome was probably in part controlled by the Cox fault set. The isopach map (Plate IX) shows the Cox faults on the southeast end of the proto-dome controlling the thickness of the Saltos Shale Member. Growth of the proto-dome and movement on the Cox fault set were contemporaneous, latest

Saucesian to early Relizian (early Miocene). The north-northeast orientation and normal separation on the Cox faults indicates extension in a west-northwest to east-southeast direction. The stresses responsible for the Cox fault set may also have been responsible for the proto-South Cuyama dome. The isopach map of the Relizian "Johnston sand" (Figure 6) indicates that the sand

thins and pinches out at the crest of the dome, implying the presence of a structural high during thetime of its deposition.

The proto-dome therefore remained as a high area after theend of

Cox faulting.

Russell Fault

The Russell fault is part of a north-northwest-trendingfault

system which includes the Chimeneas, San Juan,and Red Hills faults

(Schwade and others, 1958). This fault system transects the Cuyama

basin and joins the San Andreas fault north of Red Hills(Figure

2) in a manner analogous to the junction between the SanGabriel

and San Andreas fa-_:lts. Unlike the San Gabriel fault, the continu- 44 ation of this fault system southeast of the Russell is unknown.

Smith (1977) considered the San Juan-Chimeneas fault as part of an early trace of the San Andreas fault across which 175 kilometers

(109 miles) of right-lateral displacement accumulated during Oligo- cene and early Miocene time. He based this estimate on the occurrence of a sedimentary megabreccia in the Soledad basin that appears to have been derived from the quartz monzonite in the northern La

Panza Range, and the similarity of the La Panza quartz monzonite to a body of quartz monzonite in the southeasternmost Little San

Bernardino Mountains (Figure 1). A. Bartow (written commun., 1982) questions the interpretation of the San Juan-Chimeneas fault as an early trace of the San Andreas fault, based onhis correlation of a conglomerate of Late Cretaceous age in the La Panza Range to a similar Late Cretaceous conglomerate across the Chimeneas fault on Barrett Ridge (Figure 3). Bartow (1979) and Schwade and others (1958) estimated that the nonconformable contact between crystalline basement rocks and the Late Cretaceous conglomerate is offset nine miles in a right-lateral sense along the San Juan-

Chimeneas fault. Most of the separation of this contact is probably strike-slip because it would require four to six miles ofdip-slip movement to produce the nine miles of right-lateralseparation of

the contact. Schwade and others (1958) estimated 14 miles of right-

lateral separation ci the basement-Late Cretaceous contact onthe

Russell fault using subsurface evidence for the contactnorthwest

of the Russell Ranch oil field. Lagoe (1982) estimated nine miles 45 of right-lateral slip on the San Juan fault since the end of the

Luisian based on offset isopachs of the Monterey Formation.

The Russell fault strikes northwest and dips 60° to 70° southwest in the study area, cutting the southwest flank of the South

Cuyama dome (Plates XV, XVI, and XIII). The fault is mapped southeast along the southwest edge of the South Cuyama oil field to the limit of well control in the study area. The Russell fault is tectonically overridden by the South Cuyama fault on the south side of the valley (Plates X, XII, XIII, XIV, and XVII). Northwest of the South Cuyama oil field, subsurface control of the Russell fault is sparse, and the fault is covered by Quaternary valley deposits. The Russell fault must bend or step right northwest of the A. Cameron-Hill Brothers 22-27 well to connect with the

Russell fault mapped by Nevins (1982) along the southwest edge of the Russell Ranch oil field (Plate XVII). The Russell fault is steeply dipping to vertical at the southeast end of the

Russell Ranch oil field (Nevins, 1982).

Two episodes of activity are identified on the Russell fault; a post-Branch Canyon Sandstone-pre-Morales(?) episode and a post -

Morales(?) episode. Pre-Morales(?) displacement on the Russell fault is suspected to be strike-slip because of the dissimilarity of the pre-Morales(?) sequence on opposite sides of the fault

(Plates IV and XIII). Southwest of the Russell fault, the Branch

Canyon Sandstone and Branch Canyon Sandstone-Santa Margarita Forma- tion undifferentiate:f are nearly four times as thick as they are 46 northeast of the fault. Electric log markers in the Miocene section cannot be correlated across the Russell fault. The Arco Fisher 1 well bottoms in the nonmarine Simmler Formation, southwest of the fault, whereas no Simmler Formation is found in the study area northeast of the fault.

No piercing point offsets or horizontal separations of pre-

Morales(?) strata have been determined, probably because displacement is larger than the extent of the study area. The Simmler

Formation and the thick Branch Canyon Sandstone-Santa Margarita

Formation undifferentiated southwest of the fault could be offset from correlative strata in the subsurface of the eastern Cuyama basin. Alternatively, the Simmler Formation in the Arco Fisher

1 well could be only a local basin or graben fill like other occur- rences of the Simmler Formation reported by Cross (1962) and Bartow

(1974, 1978). Similarly, if a large component of the 3,700 feet of vertical separation of the top of the Painted Rock Sandstone

Member (Plate XIII) is dip-slip then the thicker Miocene sequence on the downthrown side of the fault could be a result of growth on the fault during deposition of the Branch Canyon Sandstone-

Santa Margarita Formation undifferentiated.

A set of northwest-trending strike-slip faults and a set of northwest-to northeast-trending normal faults mapped in the South

Cuyama oil field may have formed at the same time as the pre -

Morales(?)- post - Branch Canyon Sandstone episode of activity on the main Russell fault. The strike-slip faults strike northwest and 47 dip steeply to the southwest. They are in a crude left-stepping en echelon pattern, and they appear to connect southeastward with the main Russell fault (Plates XI and XVI). The strike-slip faults on the southeast plunge of the dome displace the isopachs of the

"Johnston sand" and the Branch Canyon Sandstone-Santa Margarita

Formation undifferentiated in a right-lateral sense (Figures 5 and

6; Plates X and XIV). The faults die out in the upper Branch Canyon

Sandstone-Santa Margarita Formation undifferentiated and do not cut the Morales(?) Formation (Plate XVIII; Figure 7). Figure 10 compares the displacement of isopachs of the "Johnston sand," Branch Canyon

Sandstone-Santa Margarita Formation undifferentiated, and the basal claystone of the Morales(?) Formation across the 72-1 fault and the

37-6 fault. The 250 foot isopach of the "Johnston sand" has been offset 4,550 feet in a right-lateral sense on the combined 72-1 and

37-6 faults. The discordance between the offsets of the Branch

Canyon Sandstone-Santa Margarita Formation undifferentiated and the

"Johnston sand" on the 72-1 fault is probably due to deposition of the former during fault growth and suggests a component of dip slip.

The downthrown side of the 72-1 fault accumulated a greater thickness of Branch Canyon Sandstone-Santa Margarita Formation undifferentiated than the upthrown side.

The normal faults strike from northwest to northeast and dip

40° to 70° to the east and west (Plates X, XI, XII, XIII, XIV, XV).

Several of the faults appear to be listric (Plate XI). The normal faults die out in the Branch Canyon Sandstone-Santa Margarita For- 48

Figure 10.Offset Isopachs Along the 72 -I Fault.

Isopach of Basal Morales (?) Formation Claystone 23 24

Isopach of Johnston Sand

Isopach of Branch Canyon Sandstone Santo Margarita, undifferentiated

30 27 South Cuyarna Oil Field

31 32 34

LOCATION MAP 4f

7 Cuomo _ Volley

T 10 N SCALE CGT 9 N 0 I 2 3 4 5000 Ft South Cuyomo 1-4MA FLT Oil Field 0<>

5Km Nih all24INE= cc' cc 5 M, 49 mation undifferentiated and do not cut the Morales(?) Formation

(Plate XVIII) (Schwing, 1982). Vertical separation of electric log marker 17 in the Saltos Shale Member varies from less than

25 feet to a maximum of 200 feet across the normal faults. The

Branch Canyon Sandstone-Santa Margarita Formation undifferentiated is thicker on the down-thrown side of the faults indicating growth of the faults during deposition of the formation. The normal faults formed at the same time as the strike-slip faults.

The middle to late Miocene normal and strike-slip faults may have formed as part of a system responding to right shear along the main Russell strike-slip fault zone. The orientation of the minor faults to the main fault zone is similar to models of wrench faults described by Wilcox and others (1973). Most of the models of wrench tectonics involve en echelon anticlinal domes along the main strike-slip fault zone. The isopach map of the Branch Canyon

Sandstone-Santa Margarita Formation (Figure 6) indicates only a slight thinning in Sec. 35-T1ON-R27W along the main Russell fault zone. The lack of doming during the post-Branch Canyon-pre-

Morales(?) episode of strike-slip could be due to a period of divergent wrenching. Divergent wrenching produces low relief folds and favors normal faulting (Wilcox and others, 1973). Local changes in strike of the wrench fault, or oblique movements of the opposed crustal blocks on a regional scale, can result in the increase of extensional or compressive features along the wrench fault.

Divergent wrenching results in the extensional vector formed by 50 the wrench shear couple to be oriented at a high angle to the wrench fault; in the case of the Russell fault the extensional vector would strike in a more westerly direction than the Russell fault. Oblique-slip on the wrench fault due to divergent wrenching would result in normal separation on the wrench fault.

A post-Morales(?) Formation episode of strike-slip displacement on the Russell fault is indicated by the structure contour map of electric log markers near the base of the Morales(?) Formation

(Plate XVIII) and the isopach map of the basal claystone of the

Morales(?) Formation (Figure 7). The Morales(?) Formation is folded into a elongate domal structure trending oblique to subparallel to the Russell fault. The crest of the dome itself consists of a series of en echelon axial culminations which trend into the Russell fault in a crude right-stepping orientation

(Plate XVIII). The structurally highest culmination is offset

4,500 feet in a right-lateral sense by the Russell fault. The

100-foot isopach of the basal claystone of the Morales(?) Forma- tion is offset 5,600 feet in a right-lateral sense by the Russell fault. The disagreement between the offset estimates is probably due to the low angle of incidence of the claystone isopachs with the Russell fault. The basal claystone is thicker along the Russell fault, possibly indicating the fault locally controlled subsidence and deposition of the claystone.

The en echelon orientation of the axial culminations is similar to the orientation of en echelon folds produced along wrench faults 51 in clay-model analogs described by Wilcox and others (1973). The

Morales(?) dome is similar to domes along the relatively small displacement Newport-Inglewood trend (Harding, 1973), except the

Morales(?) dome is smaller in amplitude.

The complex structure along the Russell fault is the result of compressive and extensional stresses formed along a right-lateral shear system oriented northwest-southeast. Several episodes of activity on the fault zone area, over a long interval of time resulted in the tectonic overprinting of the structural style of each episode on earlier structures. The Cox fault set and dome growth during late

Saucesian to early Relizian age may also have formed in response to an episode of right-lateral shear on the main Russell fault.

The en echelon orientation of Vaqueros age submarine troughs also is diagnostic of Oligocene and early Miocene wrench fault tectonics along the Russell fault. Confirmation of early activity on the

Russell fault must await comparison of piercing-point offsets of the Vaqueros and Monterey Formations across the fault.

South Cuyama Fault

The South Cuyama fault trends slightly north of west along the southern edge of the Cuyama Valley (Figures 3 and 8). Rocks of the Sierra Madre Mountains were thrust northward over the Cuyama

Valley sequence along the South Cuyama fault. The South Cuyama fault tectonically overrides the Russell fault and the South Cuyama dome (Plates X, XII, XIII, XIV, and XIX). Subsurface control of 52 the South Cuyama fault indicates it dips south 20° to 25° over the southwest part of the dome and varies in strike from west to northwest

(Plate XIX). South of the Arco Herren 37-35 well, the fault steepens in dip to 35° to 40° (Plates XII and XIX). West of the South Cuyama oil field, the Arco Homan C-1 well is the only subsurface control of the South Cuyama fault. Here the fault strikes slightly north of west and dips 45° to 50° to the south. The down dip extension of the South

Cuyama fault cannot be determined. The fault may steepen with depth as shown by Vedder and Repenning (1975), or it may flatten into a bedding plane slip as suggested by Schwade and others (1958). The bedding beneath the South Cuyama fault is subparallel with the fault

(Plates XII and XIII) and could indicate a bedding plane fault.

Alternatively, the parallelism of bedding beneath the thrust could be related to loading of the overlying plate; the thrust moved out across flat-lying strata which were then depressed downward so that they dip toward the fault.

In the South Cuyama oil field, the South Cuyama fault juxtaposed Santa Margarita Formation over deformed alluvium (Plate

III). Steep dips in the deformed alluvium near the South Cuyama fault (Vedder and Repenning, 1975) indicate the beds were folded by drag along the fault. The Morales(?) Formation and deformed alluvium in the subsurface beneath the South Cuyama fault are deformed adjacent to the fault; however it is not possible to map any drag folds.

Deformed alluvium appears concordant with the underlying 53

Morales(?) Formation in the Cuyama Valley, and both are overridden by the South Cuyama fault. Deformed alluvium also lies directly on folded Santa Margarita Formation in the upper plate of the fault

(Plates III, XIII, and XIV) indicating the South Cuyama fault moved during the time of deposition of the upper Morales(?) Formation and the deformed alluvium such that the youngest deformed alluvium overlapped the upper plate of the thrust. An increase in the percent- age of gravel in the deformed alluvium towards the South Cuyamafault could indicate contemporaneous uplift on the South Cuyama fault during deposition of this alluvium (Plates XII and XIII). The fault trace is far from the range front in the study area, suggesting a long period of pedimentation after the end of faulting.Older alluvium of probable late Pleistocene age is cut by the south

Cuyama fault in Sec. 26, T1ON, R27W and southeast of the South

Cuyama oil field (Plate III), indicating late Pleistocene movement of the fault. Younger alluvial deposits are not displaced by the

South Cuyama fault.

The Miocene sequence in the upper plate of the South Cuyama

fault is folded into sharp, north-verging anticlines and synclines

(Plate III). Cross sections B-B', D-D', E-E', and F-F' (Plates X,

XII, XIII, and XIV) indicate the folds are rootless.The more

competent beds of the Branch Canyon Sandstone arefolded into broad

folds whereas the less competent, finer grained strata of Santa

Margarita Formation are folded much more sharply.The axes of the

upper plate folds are parallel to the traceof the South Cuyama fault. 54

Vedder and Repenning (1975) mapped several minor thrust faults in the upper plate of the South Cuyama fault (Plate III). These thrusts are parallel to the main South Cuyama fault and thrust the lower Santa Margarita Formation over the upper Santa Margarita For- mation. Correlation of electric log markers in the Santa Margarita

Formation of the upper plate indicates several minor thrust faults which have not been mapped at the surface (Plate XIV). Electric log markers are repeated by the minor thrust faults and are subparallel to the thrust faults suggesting they are bedding plane-slips which must ramp across bedding somewhere downstructure.

The Ozena fault is a southwest-dipping thrust fault which dies out westward in the southeast part of the study area (Figure 8,

Plate III). The structural trend of the Ozena fault continues westward as a tightly folded anticline referred to as the Ozena anticline (Plates III and X). The Ozena fault apparently increases in displacement southeastward as the South Cuyama fault dies out.

The Ozena fault may have been a north-dipping normal fault during the late Oligocene-early Miocene (Bartow, 1974). Vedder

(1970) mapped a sedimentary breccia in the Caliente Formation adjacent to the north side of the fault in the Santa Barbara Canyon area, southeast of the study area. This breccia apparently was derived from uplifted Eocene strata on the south side of the Ozena fault.

The South Cuyama fault and Ozena fault were active as thrust faults in the Pleistocene in response to north-south compression. 55

Morales Paul:

The north-dipping Morales fault trends west-northwest along the north edge of the Cuyama Valley in the study area (Figure

8). The location of the surface trace of the Morales fault is uncertain. No subsurface data on the fault are available in the study area. Dibblee (1976) mapped the fault close to the range front, whereas Vedder and Repenning (1975) mapped the fault 300 to

3,000 feet south of the range front. T. Davis (1980, person. commun.) mapped late Quaternary fault scarps along the Caliente

Range front suggesting the surface trace of the basal Caliente

Range thrusts is near the topographically distinct range front.

The Morales fault thrusts the very thick Miocene sequence in the Caliente Range southward over a thinner sequence beneath Cuyama

Valley (Plate IV). The juxtaposition of 7,000 feet of Vaqueros

Formation north of the fault against the less than 1,000 feet of

Vaqueros south of the fault was previously noted by Schwade and others (1958) and Bartow (1974). Bartow (1974) also noted the restriction of the sandy facies of the Simmler Formation to areas north of the Morales fault and the conglomerate facies to areas

south of the fault.

The downdip extension of the Morales and related Caliente Range

thrust faults is controversial. Schwade and others (1958) indicated

that the thrust faults flatten with depth and become bedding-plane

thrusts. They suggested that the thrust faults tectonically 56 overlie a steep probable pre - Miocene lateral fault zone based on the juxtaposition of different pre-Miocene rocks along the Morales fault.

This steep fault zone probably was a large normal fault during the early Miocene and accumulated a very thick section of Vaqueros

Formation on the downthrown block, north of the fault. The age and correlation of pre-Miocene strata beneath the Cuyama Valley are too poorly understood to be used as evidence for lateral displacement on the Morales fault. Smith (1977) suggested that the restriction of the sandy facies of the Simmler to areas north of the Morales fault and the conglomerate facies to areas south of the fault, and facies changes in the Pattiway Formation across the fault indicated the presence of a lateral fault. Bartow (1974) believed that the Morales fault steepens with depth and marks the position of an early

Miocene normal fault which was later reactivated as a reverse fault.

In Bartow's interpretation, the Morales fault is the fault which strongly influenced the thick accumulation of Vaqueros Formation in the Caliente Range. Alternatively, the juxtaposition of different thicknesses of Vaqueros Formation along the Morales fault could be due to lateral displacement on the proposed sub-Morales fault or the Morales fault during the Miocene. A series of left- stepping en echelon domes expressed in middle Miocene and older strata is exposed in the Caliente Range (Figures 3 and 8). These domes are cut by numerous, generally north trending, small displacement normal faults that appear to die out upsection in the 57

Caliente Formation. Vedder (1973) noted that some of the faults are intruded by basalt, and others are folded, indicating that these normal faults are of Miocene age. The left-stepping en echelon orientation of the Caliente Range domes is similar to the orientation of folds along a left-lateral wrench fault, using the model of Wilcox and others (1973).

The Morales fault thrusts Miocene strata over Pliocene-Pleis- tocene continental strata (Schwade and others, 1958; Vedder and

Repenning, 1975). Older alluvial deposits and younger alluvium are cut by the fault indicating major displacement on the fault occurred in late Quaternary time. Like the South Cuyama fault, the Morales thrust fault probably formed in response to north-south contraction.

Tectonic Ridges

Several elongate ridges of older alluvium are found in the center of Cuyama Valley, approximately one mile north of Highway

166 (Figure 3, Plate III). The ridges are oriented in a right- stepping en echelon pattern and trend slightly north of west.

The westernmost ridge is Turkey Trap Ridge, and the eastern ridges are known as Graveyard Ridges. Upson and Worts (1951) suggested that the ridges were fault-controlled based on their en echelon orientation, morphology, and the occurrence of springs along the ridges.

They concluded that the ridges were either tilted fault blocks or pressure ridges along the eastward continuation of one of the 58

Caliente Range thrust faults. T. Davis (1982, person. commun.) suggested the ridges could be pressure ridges formed along a strike- slip fault. This is referred to as the Turkey Trap Ridge fault in this report. It has not been recognized in the subsurface (Plate VIII).

The fault cuts older continental deposits and alluvium (Upson and Worts, 1951; T. Davis, 1982 person. commun.). Upson and Worts

(1951) cite a report of ground rupture on trend with the ridges in Sec. 23, T1ON, R25W, after an earthquake about 1900 A.D. 59

GEOLOGIC HISTORY

The development of the Cuyama basin is a result of both Paleo- gene and Neogene tectonics. Several early Tertiary basins, including the Sierra Madre basin of Chipping (1972), formed in a continental borderland as a result of proto-San Andreas wrench tectonism during the Paleogene (Nilsen and Clarke, 1975). An unnamed marine succession composed of conglomerate, sandstone, and shale of Late

Cretaceous and early Tertiary age was deposited in a tectonically active basin. Oligocene nonmarine strata composing the Simmler

Formation overlie these marine rocks with angular unconformity.

The age of deformation of the pre-Simmler strata is not known, but it could be as young as Oligocene. A sandstone facies of the

Simmler Formation was deposited on a broad alluvial plain by small to moderate-sized streams (Bartow, 1974; 1978; Bohannon, 1976).

The conglomerate facies of Bartow (1974, 1978) represents large alluvial fans shed northward into the basin as a result of active normal faulting. The South Cuyama oil field area was apparently a highland during the time of deposition of the Simmler Formation and thus did not receive any alluvial deposits (Bartow, 1978, cf.

Figure 8). The Simmler Formation found in the Arco Fisher 1 well may have been deposited in the eastern Cuyama basin and was displaced by subsequent right-lateral movements on the Russell fault to its present location. The conglomerate facies of the Simmler Formation buttresses against and thins over basement highs in the western 60

Cuyama basin (Bartow, 1974; 1978). Bartow (1974, 1978) believed

that the patchy distribution of the Simmler Formation in the La

Panza Range and Cuyama Gorge area is caused by deposition within re-entrants in the older terrane along the basin margin. A marine transgression and rapid subsidence during the late Oligocene (Zemor- rian) marked the initiation of a major tectonic event.

The shallow marine Quail Canyon Sandstone was deposited during the initial stages of the late Oligocene transgression. The near- shore sands were deposited on a beveled surface of low topography underlain by deformed Late Cretaceous and/or early Tertiary strata in the South Cuyama area. Rapid subsidence of the basin during deposition of the Quail Canyon Sandstone abruptly dropped the shallow marine shelf deposits to bathyal depths. Large alluvial fans formed northeast of the Chimeneas, Nacimiento, and Ozena faults, along which basin subsidence occurred (Bartow, 1974;

1978) during deposition of the Quail Canyon Sandstone and lower

Soda Lake Shale. Warping of the basin in the study area resulted in thin turbidites and hemipelagic silts of the Soda Lake Shale ponding in low areas. Continued warping during deposition of the

Soda Lake Shale and Painted Rock Sandstone resulted in thinning of these units over the structural highs. An episode of right- lateral wrench faulting along the Russell fault during the early

Miocene is suggested by the deposition of the Vaqueros in a series of right-stepping en echelon submarine troughs trending obliquely to the Russell fault. The magnitude of the displacement, if any, 61 along the fault is not known.

In the Caliente Range, only the lowermost part of the Soda

Lake Shale represents deposition during transgression. The remainder of the member was deposited during progradation, suggesting maximum basin depths were reached very early during the transgression (Bartow, 1974). Thus the upper Soda Lake Shale and all of the Painted Rock Sandstone were deposited during a regression: the basin filled more rapidly than it subsided. The upper Soda

Lake Shale and Painted Rock Sandstone deltas prograded into the basin from its north end and along its southeast side (Bartow,

1974). Schwade and others (1958) suggested that a large normal fault beneath the Caliente Range was active during deposition of the Vaqueros Formation. This fault may have controlled basin subsidence and sedimentation, accumulating a great thickness of the prograding shelf and deltaic deposits of the Soda Lake Shale and Painted Rock Sandstone north of the fault and only a very thin sequence south of the fault, beneath the Cuyama Valley.

Alternatively, the thick Painted Rock Sandstone-Soda Lake Shale sequence north of the fault could have been juxtaposed against a thin sequence by strike-slip faulting. In the Caliente Range, a series of left-stepping en echelon domes expressed in middle

Miocene and older strata could have formed in response to left- lateral wrench faulting. The domes are cut by numerous small-displacement normal faults of probable Miocene age (Vedder, 1973).

These normal faults could have formed in response to extension 62 related to wrench faulting.

A second transgression during the late Saucesian marked another major episode of basin subsidence. The shelf deposits of the Paint- ed Rock Sandstone are overlain by the Saltos Shale whichwas deposited at middle bathyal depths (1,600-4,800 feet; 500-1,500 meters) over much of the Cuyama basin (Lagoe, 1981; 1982). Sandstone interbeds in the Saltos Shale were deposited by turbidity currents and other grain-flow processes (Lagoe, 1981; 1982). Several structural features became active during the late Saucesian to Relizian.

Normal displacement on the Cox fault set controlled basin subsidence.

East of the Cox fault zone, a large submarine fan was forming (Lagoe,

1981; 1982). Growth of the Cox faults during deposition of the

Saltos Shale resulted in a greater accumulation of the Saltos

Shale on the downthrown sides of these faults. Structural growth of a proto-South Cuyama dome occurred at this time, resulting in thinning of the Saltos Shale over the dome. The lower "Triple" basalt flow of Eaton (1939) was extruded in the Caliente Range during the Relizian. The east-west extension indicated by the orientation of the Cox fault set and dome growth could be edge effects of an early Miocene episode of wrench faulting along the Russell faldt, as suggested by wrench fault models of Wilcox and others (1973).

The basin filled by progradation of shallow marine and deltaic deposits from the southeast to the northwest during the Miocene

(Lagoe, 1982). In the Caliente Range the Branch Canyon Sandstone 63 exhibits several progradational-retrogradational cycles during the middle Miocene (Clifton, 1981). The deltaic and shallow marine deposits of the Branch Canyon Sandstone grade laterally eastward into continental redbeds of the Miocene Caliente Formation. A granitic upland area east of the San Andreas fault was the source for the Caliente Formation during the Miocene (Clifton, 1968;

1981). Trapping of terrigenous material around the basin margins during a Luisian high sea-level stand enhanced the biogenic compo- sition of the Whiterock Bluff Shale (Phillips, 1976; Lagoe, 1982).

By late Miocene time, the shallow marine Santa Margarita Formation was being deposited over much of the basin. Phosphatic claystone of the Santa Margarita Formation was deposited along certain shelf areas during a high sea level stand in the Mohnian(Lagoe, 1982;

Fritsche, 1969). Subsidence slowed during the late Miocene (Lagoe,

1982), and by Pliocene time, most of the basin was receiving nonmarine deposits. In the South Cuyama area, the Morales(?) Formation probably represents the transition from marine to nonmarine deposition. In parts of the basin, post-Santa Margarita deformation resulted in an angular unconformity at the base of the Morales

Formation (Nevins, 1982).

Major right-lateral displacement occurred on the Russell fault during the late Miocene, prior to deposition of theMorales(?)

Formation. The right-lateral shear system resulted in an east-west component of extension which produced numeroussmall-displacement normal faults. Several northwest-trending strike-slip faults 64 with small displacement formed adjacent to the Russell fault in response to the right-lateral shear system. Active wrench tectonism during the deposition of the upper Branch Canyon Sandstone-

Santa Margarita Formation undifferentiated resulted in the greater accumulation of deposits in the downthrown blocks and the disrup- tion of sedimentation patterns. Following deposition of the lower part of the Morales(?) Formation, another episode of right-slip occurred on the Russell fault. The Morales(?) Formation was folded into an elongate dome oriented subparallel to the Russell fault due to the north-south-oriented principal compressive stresses associated with northwest-trending right-lateral faulting. The dome consisted of several right-stepping en echelon axial culminations which subsequently were offset approximately 4,500 feet by the main Russell fault. Clifton (1981) suggested that the change in the progradational pattern near the top of the Miocene section, eruption of the "Triple" basalts of Eaton (1939), and the development of a major erosional surface may indicate the initiation of Neogene displacement on the San Andreas fault.

During the Pleistocene, a north-sout contractile regime re- placed the dominantly extensional and strike-slip regime of the

Miocene (Schwing, in press). In the Sierra Madre Mountains,

Miocene and older rocks were tightly folded into rootless north- verging anticlines and synclines. The finer grained strata of the

Santa Margarita Formation underwent more ductile deformation in comparison with the coarse-grained rocks of the Branch Canyon

Sandstone. The rocks were folded and thrust northward along the 65 south-dipping South Cuyama fault and rejuvenated Ozena fault. The

South Cuyama fault tectonically overrode the Russell fault and the

South Cuyama dome. Miocene rocks were thrust over the Morales(?)

Formation and Pleistocene alluvial deposits. The alluvial deposits overlapped the South Cuyama fault and were themselves overridden and deformed by later movements of the fault, and so the deformed alluvium lies unconfornably on deformed Miocene rocks in the upper plate. The north-dipping Morales fault thrust Paleocene to

Miocene rocks in the Caliente Range southward over Pliocene and

Pleistocene alluvial deposits during the late Pleistocene (Vedder,

1973). The left-stepping en echelon domes of the Caliente Range were exposed during Pleistocene uplift of the range.

Recurrent activity on the South Cuyama fault during the late

Pleistocene folded and faulted older alluvial deposits along the fault. Recent activity on the Caliente Range thrust faults has deformed and cut recent alluvial deposits. Uplift of the Caliente

Range and Sierra Madre Mountains during the Pleistoceneformed the present day Cuyama Valley. 66

CONCLUSION

The structural features in the South Cuyama oil field and adjacent areas probably formed in response to wrench tectonism along the Russell fault throughout the Neogene. The orientation and sense of displacement of faults and the orientation of folds along the Russell fault are analogous to the structural style produced in clay-cake wrench fault models of Wilcox and others

(1973). Paleogeologic mapping techniqueshave revealed the presence of wrench tectonic features along the Russell fault since the late Oligocene. Recurrent northwest-southeast right-lateral shear on the main Russell fault resulted in a complex fault pattern along the fault which cuts the South Cuyama dome. The dome itself had several episodes of growth, probably related to compression within the right-lateral shear system.

The tectonic style of the Neogene Cuyama basin is similar to the middle Miocene wrench tectonic regime described by Graham

(1978) in the Salinas basin. These wrench-fault-controlled basins formed a Neogene continental borderland within the San

Andreas transform fault system. The present-day contractile regime in the Cuyama basin, characterized by east-west-trending thrust

faults, obscures the older wrench tectonic regime of the Cuyama basin. 67

REFERENCES CITED

Bohannon, R. G., 1976, Mid-Tertiary nonmarine rocks along the San Andreas fault in southern California: Univ. California, Santa Barbara, unpub. Ph.D. thesis, 311 p.

Bartow, J. A., 1974, Sedimentology of the Simmler and Vaqueros Formations in the Caliente Range-Carrizo Plain area, Califor- nia: Stanford Univ., unpub. Ph.D. thesis, 163 p.

, 1978, Oligocene continental sedimentation, Califor- nia: Jour. Sed. Petrology, v. 48, p. 75-98.

Cawley, J. J., 1962, Aborigines of the Carrizo Plains, in Guide- book to the geology of Carrizo Plain and San Andreas fault: San Joaquin Geol. Soc. and Pacific Secs. Am. Assoc. Petroleum Geologists and Soc. Econ. Paleontologists and Mineralogists, p. 36.

Chipping, D. H., 1970, The petrology and paleogeography of Cretace- ous and lower Tertiary strata in the vicinity of Cuyama Valley, California: Stanford Univ., unpub. Ph.D. thesis, 179 p.

, 1972, Early Tertiary paleogeography of central California: Am. Assoc. petroleum Geologists Bull., v. 56, p. 480-493.

Clifton, H. E., 1968, Possible influence of the San Andreas fault on middle and probable late Miocene sedimentation, southeastern Caliente Range: Stanford Univ. Pub. Geol. Sci., v. 11, p. 183- 190.

, 1981, Progradational sequences in Miocene shoreline deposits, southeastern Caliente Range, California: Jour. Sed. Petrology, v. 51, p. 165-184.

Cross, R. K., 1962, Geology of the Carriso-Cuyama basin, in Guide- book to the geology of Carrizo Plain and San Andreas fault: San Joaquin Geol. Soc. and Pacific Secs. Am. Assoc. Petroleum Geologists and Soc. Econ. Paleontologists and Mineralogists, p. 27-36.

Dibblee, T. W., Jr., 1973a, Regional geologic map of San Andreas and related faults in Carrizo Plain, Temblor, Caliente, and La Panza Ranges and vicinity, California: U.S. Geol. Survey Misc. Geol. Inv. Map 1-757. Dibblee, T. W., Jr., 1973b, Stratigraphy of the southern Coast Ranges near the San Andreas fault from Cholame to Maricopa, California: U.S. Geol. Survey Prof. Paper 764, 45 p.

Eaton, J. E., 1939, Geology and oil possibilities of Caliente Range, Cuyama Valley, and Carrizo Plain, California: Calif. Jour. Mines and Geol., v. 35, p. 255-274.

Eaton, J. E., Grant, U. S., and Allen, H. B., 1941, Miocene of Caliente Range and environs, California: Amer. Assoc. Pet- roleum Geologists Bull., v. 25, p. 193-262.

Edwards, L. M., 1971, Geology of the Vaqueros and Rincon Formations, Santa Barbara Embayment, California: Univ. California, Santa Barbara, unpub. Ph.D. thesis, 240 p.

English, W. A., 1916, Geology and oil prospects of Cuyama Valley, California: U.S. Geol. Survey Bull. 621-M, p. 191-215.

Fritsche, A. E., 1969, Miocene geology of the central Sierra Madre Mountains, Santa Barbara County, California: Univ. California, Los Angeles, unpub. Ph.D. thesis, 385 p.

Graham, S. A., 1978, Role of Salinian block in Evolution of San Andreas Fault System, California: Am. Assoc. Petroleum Geologists Bull., v. 62, p. 2214-2231.

Harding, T. P., 1973, Newport-Inglewood trend, California - an example of wrenching style deformation: Am. Assoc. Petroleum Geologists Bull., v. 57, p. 97-116.

Hill, M. L., Carlson, S. A., and Dibblee, T. W., Jr., 1958, Strati- graphy of Cuyama Valley-Caliente Range area, California: Am. Assoc. Petroleum Geologists Bull., v. 42, p. 2973-3000.

Ingle, J. C., Jr., 1980, Cenozoic paleobathymetry and depositional history of selected sequences within the southern California continental borderland: Cushman Found. Foram. Res., Spec. Publ. 19, p. 163-195.

Jennings, C. W., 1958, Geologic map of California, Olaf P. Jenkins edition, San Leis Obispo Sheet: California Div. Mines Map Sheet.

, 1959, Geologic map of California, Olaf P. Jenkins edition, Santa Maria Sheet: California Div. Mines Map Sheet.

, and Strand, R. G., 1969, Geologic map of Califor- nia, Olaf P. Jenkins edition, Los Angeles Sheet: California Div. Mines Map Sheet. 69

Kistler, R. W., 1976, Mesozoic Paleogeography of California: A Viewpoint from Isotope Geology, in Howell, D. G., McDougall, K. W., eds., Mesozoic Paleogeography of the Western United States, Pacific Coast Paleogeography Symposium 2: Pacific Section, Soc. Econ. Paleontologists and Mineralogists, p. 75-84.

Lagoe, M. B., 1981, Subsurface facies analysis of the Saltos Shale Member, Monterey Formation (Miocene) and associated rocks, Cuyama Valley, California, in Garrison, R. E., and Douglas, R. G., eds., The Monterey Formation and related siliceous rocks of California: Pacific Section, Soc. Econ. Paleontolo- gists and Mineralogists, Los Angeles, p. 199-211.

, 1982, Stratigraphy and paleoenvironments of the Monterey Formation and associated rocks, Cuyama basin, Califor- nia: Stanford Univ., unpub. Ph.D. thesis, 216 p.

Madsen, S. H., 1959, The geology of a portion of the Salisbury Canyon area, northwestern Santa Barbara County, southern California: Univ. California, Los Angeles, unpub. M.A. thesis, 82 p.

Nevins, B. B., 1982, Structural evolution of the Russell Ranch oil field and vicinity, southern Coast Ranges, California: Oregon State Univ., M.S. thesis, 69 p.

Nilsen, T. H., and Clarke, S. H., Jr., 1975, Sedimentation and tectonics in the early Tertiary continental borderland of central California: U.S. Geol. Survey Prof. Paper 925, 64 p.

Page, B. M., 1981, The southern Coast Ranges, in Ernst, W. G., ed., The geotectonic development of California, Prentice-Hall, New Jersey, p. 329-417.

Phillips, F. J., 1976, Miocene Foraminifera from Caliente Mountain, San Luis Obispo Co., California: Univ. California, Berkeley, unpub. M.A. thesis, 106 p.

Poore, R. Z., 1980, Age and correlation of California Paleogene benthic foraminiferal stages: U.S. Geol. Survey Prof. Paper 1162-C, 8 p.

Repenning, C. A., and Vedder, J. G., 1961, Continental vertebrates and their stratigraphic correlation with marine mollusks, eastern Caliente Range, California: U.S. Geol. Survey Prof. Paper 424-C, p. 235-239. 70

Ross, D. C., 1978, The Salinian block A Mesozoic granitic orphan in the California Coast Ranges, in Howell, D. G., McDougall, K. A., eds., Mesozoic Paleogeography of western United States, Pacific Coast Paleogeography Symposium 2: Pacific Section, Soc. Econ. Paleontologists and Mineralogists, p. 509-522.

Sage, O. G., 1973, Paleocene geography of southern California: Univ. California, Santa Barbara, unpub. Ph.D. thesis, 250 p.

Schwade, I. T., Carlson, S. A., and O'Flynn, J. B., 1958, Geologic environment of Cuyama Valley oil fields, California, in Weeks, L. G., ed., Habitat of oil, Am. Assoc. Petroleum Geologists, p. 78-98.

Schwing, H. F., 1982, Tectonic history of the Cuyama basin, southern Salinian block, California: Geol. Soc. America Abstracts with Programs, v. 14, p. 232.

, in press, Interaction between the Transverse Ranges and Salinian block in the South Cuyama oil field, Cuyama Valley, California, in Geology and Mineral Wealth- California Transverse Ranges Volume: South Coast Geol. Soc.

Smith, A. R., 1964, Geologic map of California, Olaf P. Jenkins edition, Bakersfield Sheet: California Div. of Mines Map Sheet.

Smith, D. P., 1977, San Juan-St. Francis fault--hypothesized major middle Tertiary right-lateral fault in central and southern California: California Div. Mines and Geology Spec. Report 129, p. 41-50.

Turner, D. L., 1970, Potassium-argon dating of Pacific Coast Miocene foraminiferal stages: Geol. Soc. Am. Spec. Paper 124, p. 91-219.

Upson, J. E., and Worts, G. F., Jr., 1951, Ground water in the Cuyama Valley, California: U.S. Geol. Survey Water-Supply Paper 1110-B, 81 p.

Vedder, J. G., 1968, Geologic map of Fox Mountain quadrangle, Santa Barbara County, California: U.S. Geol. Survey Map 1-547.

, 1970, Geologic map of the Wells Ranch and Elkhorn Hills quadrangles, San Luis Obispo and Kern Counties, California: U.S. Geol. Survey Map 1-585.

, 1973, Geologic framework and correlation of Miocene rocks in the Caliente Range, in Sedimentary facies changes in Tertiary rocks--California Transverse and Southern Coast Ranges: Pacific Sec. Soc. Econ. Paleontologists and Mineralo- gists Guidebook, Field Trip 2, 1973, Ann. Mtg., p. 42-53. 71

Vedder, J. G., and Repenning, C. A., 1975, Geologic map of the Cuyama and New Cuyama quadrangles, San Luis Obispo and Santa Barbara Counties, California: U.S. Geol. Survey Map 1-876.

Wilcox, R. E., Harding, T. P., and Seely, D. R., 1973, Basic wrench tectonics: Am. Assoc. Petroleum Geologists Bull., v. 57, p. 74-96.

Zulberti, J. L., 1954, South Cuyama oil field: Calif. Div. Oil and Gas, Summ. Operations--California Oil Fields, v. 40, No. 1, p. 41-43.