The Kern River Formation, Southeastern San Joaquin Valley, California
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The Kern River Formation, Southeastern San Joaquin Valley, California GEOLOGICAL SURVEY BULLETIN 1529-D The Kern River Formation, Southeastern San Joaquin Valley, California By J. ALAN BARTOW and GARDNER M. PITTMAN CONTRIBUTIONS TO STRATIGRAPHY GEOLOGICAL SURVEY BULLETIN 1529-D UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1983 UNITED STATES DEPARTMENT OF THE INTERIOR JAMES G. WATT, Secretary GEOLOGICAL SURVEY Dallas L. Peck, Director Library of Congress Cataloging in Publication Data Bartow, J. A. The Kern River Formation, southeastern San Joaquin Valley, California. (Contributions to stratigraphy) (Geological Survey Bulletin 1529-D) Bibliography: 17 p. 1. Geology, Stratigraphic Tertiary. 2. Geology California San Joaquin Valley. I. Pittman, Gardner M. II. Title. III. Series. IV. Series: Geological Survey Bulletin 1529-D. QE75.B9 no. 1529-D 557.3s [551.7'86'0979488 82-600112 AACR2 [QE90.S14] For sale by the Branch of Distribution, U.S. Geological Survey, 604 South Pickett Street, Alexandria, VA 22304 CONTENTS Page Abstract ....................................... 1 Introduction ..................................... 1 Acknowledgments ................................ 2 Kern River Formation ............................... 2 Lithology .................................... 5 Type section ................................ 7 Oil sands .................................... 8 Stratigraphic relations ............................. 10 Age and correlation .............................. 12 Composite reference section ............................ 13 References cited ................................... 16 ILLUSTRATIONS PLATE 1. Graphic log of type section of the Kern River Formation . In pocket FIGURE 1. Chart showing development of stratigraphic nomenclature ..... 3 2. Map showing distribution of Kern River Formation ......... 4 3. Geologic map showing location of type and reference sections of Kern River Formation ........................... 6 4. Diagrammatic section showing relative stratigraphic position of reference sections, Kern River Formation ............... 8 5. Cross section showing stratigraphic relations of late Tertiary formations in area of type section of Kern River Formation . n III CONTRIBUTIONS TO STRATIGRAPHY THE KERN RIVER FORMATION, SOUTHEASTERN SAN JOAQUIN VALLEY, CALIFORNIA By J. ALAN BARTOW and GARDNER M. PiTTMAN 1 ABSTRACT The nonmarine sedimentary deposits overlying marine Miocene strata in the Kern River area of the southeastern San Joaquin Valley were named the Kern River Group by Anderson (1911). This group was later subdivided by Diepenbrock (1933) into the Chanac, Kern River, and Etchegoin Formations. Diepenbrock's (1933) name, Kern River Formation, is herein adopted and type and composite reference sections are designated. The names Kern River Group and Kern River Series are herein abandoned. The Kern River Formation crops out in a crescent-shaped belt about 80 km (50 mi) long and up to 20 km (12 mi) wide; it reaches its maximum thickness of 800 m (2,600 ft) in the subsurface west of the outcrop. The formation consists mostly of poorly sorted fluvial sandstone and conglomerate with interbeds of siltstone or mudstone and becomes finer grained northward and westward. Two oil-producing zones occur in the lower part of the formation in the Kern River oil field located over a structural salient produced by the southwest-plunging Bakersfield arch. The Kern River Formation, or its basinward marine partial equivalent, the Etchegoin Formation, unconformably overlies the Chanac Formation. The Kern River is uncon- formably overlain by Pleistocene alluvium. The Kern River is considered to be late Miocene, Pliocene, and early Pleistocene(?) in age on the basis of contained mammals and its relations to adjacent dated formations. INTRODUCTION The name Kern River Group was first applied by Anderson (1911, p. 90, 95-96) to the nonmarine gravels, sands and clays unconformably overlying the marine Miocene rocks in the Kern River area of the southeastern San Joaquin Valley, California.2 As originally defined by Anderson, the unit probably included beds that are now commonly referred to the "Santa Margarita"3 or Chanac Formations. Since then '(Jetty Oil Co., Ventura, Calif. 2Anderson (1905, p. 187-188, 191) applied the name Kern River Be>ds to Miocene marine rocks stratigraphically below what was later named the Kern River Group. The description did not include the overlying nonmarine deposits. 3Quotes are used here to indicate that the name Santa Margarita is probably misapplied in the southeastern San Joaquin Valley because of the uncertainties of correlation with the type locality west of the San Andreas fault. Dl D2 CONTRIBUTIONS TO STRATIGRAPHY the name has been used in a variety of ways (fig. 1). Subsurface evidence from wells drilled after Anderson's definition indicated the presence of a wedge of marine Etchegoin Formation within the Kern River Group. This marine wedge was used by Diepenbrock (1933) to subdivide the nonmarine Kern River Series into an upper unit called the Kern River Formation and a lower unit referred to the Chanac Formation with the wedge of Etchegoin in the middle. Thus the name Kern River was used by Diepenbrock for both a unit of group rank and for a formation within that group. Use of the name Kern River by various authors without specifying whether formation or group was intended has probably contributed to confusion over the age and stratigraphic relations of the formation. Regional mapping in the San Joaquin Valley since 1974, with an emphasis on late Cenozoic tectonics and sedimentation, has focused new attention on the Kern River Formation and its significance in the history of the San Joaquin basin. We here adopt the name Kern River Formation of Diepenbrock (1933) and abandon the names Kern River Group and Kern River Series. ACKNOWLEDGMENTS The authors gratefully recognize the contributions of many individu als, in particular Claudia Owen for her assistance in the field, and the personnel of Getty Oil Co. We wish to thank the management of Getty Oil for the release of proprietary subsurface information and permission for Gardner Pittman, the junior author, to participate in publishing this paper. KERN RIVER FORMATION The Kern River Formation crops out in a roughly crescent-shaped belt, about 20 km (12 mi) wide at its widest point, from Caliente Creek on the south to the vicinity of Terra Bella on the north, a distance of about 80 km (50 mi) (fig. 2). In cross section, the formation forms a westward-thickening wedge that has a thickness of about 450- 500 m (1,475-1,600 ft) near the west edge of the outcrop belt. In the subsurface farther west, it reaches a maximum thickness of 800 m (2,600 ft). It thins northward, appearing to be about 150 m (500 ft) thick near Richgrove (Klausing and Lohman, 1964, fig. 124.2). O O co 5? 3J ^ - = 33 CO co 55" C D" O < fl> C CD - '! -» CO T3 o Q ~« I o ~" CO 3 ^ o> ^ : 0.3 > o' r- CD Q. = o ,* c -* ffl o o / 2 » £ rt m ^ S 3 ) s- 3 E' *i co; C-S T / <" o 3 CO i o" H / m co (/>§ CO o q Q) ^ CD 3" 3 1 ) z. CD :n CD§ ?2. Q> O~ \ CD CQ - ^ C^ ^ 2. cB f* ( 3 "l Q. g> / Kern River Series C o f Tl 0 H ""5 / \ /S_ _ Tl _ CD' -i CD 2 " / oo ) / o 5 o CO ® Q)3 O"3 5'0" I " / i ? V 3 ^ 3 f ? GO O~ §s / a.3 / sS s|3 3 - / o " i o°. § CD Sj 3 33 -" -n C/) / / m Tl ^ 1 * / / _? fX. ?T 'B C/) c O S?2 / Cha nac I ^ | f COCO 30) / U C 'la ll -> CO 3' OT? ^cS / Form;ation / 5. ? 5' 3" -» / /W\l 3 9L CD 0)| Kern River Formation w 1 - Q) ^. N 1 M ? o ^/Jff5 g _.3 2. 3" <W i £ 3 f») 3 ^ C/) c O sIN^ 1 CO Q <CQ ^ 2. 3 ^ s r Is ssS < § Q>. 0. ^CQ ° ^^ CD < O Q) D sr 3 .^| ( 1 1 ° (Is 0) ® => of Kern River Series ( Kern River Group i / " Tl /tn 3 ! "1 fl) O) "^ o -^ | TI m o1 ^ I o «~* -i CO *_ S- (/> C O I s 1 5 03 1 "i O ^ 3D 7C °L< M o> 35> ~ a? a. CD Q> 0 CQ Q> 3 3d) r* Q) fi/fii i.i'5 "cFg. CD 3 * -. Of §1^ 5'1. o- 3 0) 3 « | 3 3 3 ^ C/) I " C i/ 01 ;» ll N -n 3 < O (r^Y TI m o-n alluvium Q. CO I ^ Formation Silt Mountain Round CD" 3- /f g o 3 33 ^ Older " N 3 3 ] 3 m M <' ? 8? ? f S O> / Q> CQ 2. ? 3 ° \ O O This "3 § / 3 5" 3 * o \ CO =K § y CD CO T a / o ) 3 TJ co'CD_ C/l O Pleisto CD Miocene Pliocene g cene 3 CO CD ea H3AIH D4 CONTRIBUTIONS TO STRATIGRAPHY 119°00' 118°45' 35°15' - 10 20 MILES 20 30 KILOMETERS EXPLANATION fl Kern River Formation Older Tertiary Western limit of Kern River (Miocene to Pleistocene?) strata basement rock outcrop oil field FIGURE 2. Distribution of the Kern River Formation in the southeastern San Joaquin Valley, California. Unpatterned areas are underlain by Quaternary sediments younger than the Kern River Formation. Base from U.S. Geological Survey, State of California, 1970, original scale 1:1,000,000. KERN RIVE R F OEMATION, CALIFORNIA D5 1JTHOLOGY Where it crops out, the K«rn River Formation consists mostly of pale-yellow to light-brown sandstone and conglomerate with interbeds of greenish-gray or greenish--t rown siltstone and mudstone. Drab col ors predominate, but red-brown mudstone can be seen locally in out crop. The deposits are generally poorly sorted and crudely bedded, although medium- and large-scale trough crossbedding is common. The sediments were deposited in a fluvial environment, probably braided river channels for the most. part. Some of the thicker siltstone or mudstone interbeds may represent the deposits in small ephemeral lakes or ponds. The Kern River Formation is coarsest in its easternmost exposures, generally the area south of the Kern River.