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The Cenozoic Evolution of the San Joaquin Valley, California

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The Cenozoic Evolution of the San Joaquin Valley, California The Cenozoic Evolution of the San ,*~*Toaquin JL \Mle\v/ California ,S. OEOLQ01CAL SURVEY PR0FE£SKWAL PAPER 1501 The Cenozoic Evolution of the San Joaquin Valley, California By J. ALAN BARTOW U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1501 UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1991 DEPARTMENT OF THE INTERIOR MANUEL LUJAN, JR., Secretary U.S. GEOLOGICAL SURVEY Dallas L. Peck, Director Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government Library of Congress Cataloging-in-Publication Data Bartow, J. Alan. The Cenozoic evolution of the San Joaquin Valley, California / by J. Alan Bartow. p. cm. (U.S. Geological Survey professional paper ; 1501) Includes bibliographical references. Supt. of Docs, no.: I 19.16:1501 1. Geology, Stratigraphic Cenozoic. 2. Geology California San Joaquin River Valley. 3. Sedimentation and depo­ sition California San Joaquin River Valley. I. Title. II. Series. QE690.B341991 551.7'8'097948-dc20 89-600313 CIP For sale by the Books and Open-File Reports Section, U.S. Geological Survey, Federal Center, Box 25425, Denver, CO 80225 CONTENTS Page Abstract 1 The sedimentary record Continued Introduction 2 Paleogene Continued Setting 2 Upper Paleocene and lower Eocene sequence 17 Previous work 2 Eocene sequence 18 Purpose and approach 3 Lower Oligocene sequence 19 Geology 3 Upper Oligocene sequence 19 Northern Sierran block 3 Neogene and Quaternary 20 Southern Sierran block 6 Lower and middle Miocene sequence 20 Northern Diablo homocline 8 Middle and upper Miocene sequence 21 West-side fold belt 9 Upper Miocene, Pliocene, and Pleistocene sequence 23 Maricopa-Tejon subbasin and south-margin deformed Upper Pleistocene and Holocene deposits 23 belt 10 Basin evolution 24 Major controls on sedimentation 12 Paleocene 25 Tectonics 12 Eocene 25 Plate tectonics 12 Oligocene 28 Regional tectonics 13 Miocene 29 Sea-level change 15 Pliocene 31 Climate 16 Pleistocene 31 The sedimentary record 16 Holocene 33 Paleogene 16 Conclusions 33 Great Valley sequence 16 References cited 34 ILLUSTRATIONS [Plates are in pocket] PLATE i. Generalized geologic map and cross sections of the San Joaquin Valley area, California. 2. Correlation of the Cenozoic stratigraphic units of the San Joaquin basin with tectonic, volcanic, and sea-level events. FIGURE i. Index map of central California - 4 2. Diagram showing interrelation of factors affecting eustasy - 16 3. Diagrammatic cross section of the northern San Joaquin Valley showing stratigraphic relations of Quaternary alluvial deposits - 24 4. Maps showing evolution of regional stress patterns in the San Joaquin Valley area - 26 5-13. Maps of the San Joaquin basin showing: 5. Late Paleocene paleogeography - 27 6. Early to middle Eocene paleogeography - 28 7. Middle Eocene paleogeography - 28 8. Oligocene paleogeography - 29 9. Early Miocene paleogeography - 30 10. Middle Miocene paleogeography - 30 11. Late Miocene paleogeography - 31 12. Pliocene paleogeography - 32 13. Pleistocene paleogeography (San Joaquin Valley) - 32 ill THE CENOZOIC EVOLUTION OF THE SAN JOAQUIN VALLEY, CALIFORNIA By J. ALAN BARTOW ABSTRACT The San Joaquin Valley, which is the southern part of the of the basin, has undergone significant late Cenozoic shortening 700-km-long Great Valley of California, is an asymmetric structural through north-directed thrust faulting at the south margin, as well as trough that is filled with a prism of upper Mesozoic and Cenozoic extreme Neogene basin subsidence north of the thrust belt. sediments up to 9 km thick; these sediments rest on crystalline The sedimentary history of the San Joaquin basin, recorded in basement rocks of the southwestward-tilted Sierran block. The San terms of unconformity-bounded depositional sequences, has been con­ Joaquin sedimentary basin is separated from the Sacramento basin to trolled principally by tectonism, but it has also been controlled by the north by the buried Stockton arch and associated Stockton fault. eustatic sea-level changes and, to a lesser degree, by climate. Plate The buried Bakersfield arch near the south end of the valley separates tectonic events that had an influence on the basin include (1) subduction the small Maricopa-Tejon subbasin at the south end of the San Joaquin during the early Tertiary that changed from oblique to normal basin from the remainder of the basin. Cenozoic strata in the San convergence in the later part of the Eocene, (2) the mid-Oligocene Joaquin basin thicken southeastward from about 800 m in the north to encounter of the Pacific-Farallon spreading ridge with the trench, and over 9,000 m in the south. the consequent establishment of the San Andreas transform, (3) the The San Joaquin Valley can be subdivided into five regions on the northwestward migration of the Mendocino triple junction that induced basis of differing structural style. They are the northern Sierran block, extensional tectonism and volcanism in adjacent areas, and (4) the the southern Sierran block, the northern Diablo homocline, the west- change in plate motions at 5 Ma that resulted in an increased component side fold belt, and the combined Maricopa-Tejon subbasin and south- of compression normal to the San Andreas transform. Other tectonic margin deformed belt. Considerable facies variation existed within the events of a more regional scale that affected the San Joaquin basin sedimentary basin, particularly in the Neogene when a thick section of include (1) clockwise rotation of the southernmost Sierra Nevada and marine sediment accumulated in the southern part of the basin, while a tectonism that produced large en echelon folds in the southern Diablo relatively thin and entirely nonmarine section was deposited in the Range, both perhaps related to Late Cretaceous and early Tertiary northern part. The northern Sierran block, the stable east limb of the right slip on the proto-San Andreas fault, (2) uplift of the Stockton arch valley syncline between the Stockton fault and the San Joaquin River, in the early Tertiary, (3) regional uplift of southern California in the is the least deformed region of the valley. Deformation consists mostly Oligocene that was a precursor to the ridge-trench encounter, (4) of a southwest tilt and only minor late Cenozoic normal faulting. The extensional tectonism in the Basin and Range province, particularly in southern Sierran block, the stable east limb of the valley syncline the Miocene, (5) wrench tectonism adjacent to the San Andreas fault in between the San Joaquin River and the Bakersfield arch, is similar in the Neogene, (6) northeastward emplacement of a wedge of the style to the northern part of the block, but it has a higher degree of Franciscan Complex at the west side of the Sierran block and the deformation. Miocene or older normal faults trend mostly north to associated deep-seated thrusting in the Cenozoic, and (7) the acceler­ northwest and have a net down-to-the-west displacement with individ­ ated uplift of the Sierra Nevada beginning in the late Miocene. ual offsets of as much as 600 m. The northern Diablo homocline, the The early Cenozoic sedimentary history of the San Joaquin basin western limb of the valley syncline between the Stockton arch and differs from that of the later Cenozoic: the former is characterized by a Panoche Creek, consists of a locally faulted homocline with northeast few long-lasting basinwide depositional sequences, whereas the latter is dips. Deformation is mostly late Cenozoic, is complex in its history, and characterized by shorter sequences of more local extent. This change in has included up-to-the-southwest reverse faulting. The west-side fold style of sedimentation took place during the Oligocene at about the belt, the southwestern part of the valley syncline between Panoche beginning of the transition from a convergent continental margin to a Creek and Elk Hills and including the southern Diablo and Temblor transform margin. Paleogene basin history was controlled principally Ranges, is characterized by a series of folds and faults trending slightly by subduction-related and proto-San Andreas fault-related tectonics oblique to the San Andreas fault. Paleogene folding took place in the and, to a lesser extent, the effects of changing eustatic sea level. A northern part of the belt; however, most folding took place in Neogene eustatic fall in sea-level was probably the principal cause for the time, during which the intensity of deformation increased southeast­ regression recorded at the end of the upper Paleocene and lower Eocene ward along the belt and southwestward toward the San Andreas fault. depositional sequence, and it contributed to most other Paleogene The Maricopa-Tejon subbasin and the south-margin deformed belt are regressions. Tectonic events related to the approach of the Pacific- structurally distinct, but genetically related, regions bounded by the Farallon spreading ridge became important in the Oligocene. Neogene Bakersfield arch on the north, the San Emigdio Mountains on the south, basin history was controlled principally by the tectonic effects of the the Tehachapi Mountains on the east, and the southeast end of the fold northwestward migration of the Mendocino triple junction along the belt on the west. This combined region, which is the most deformed part California continental margin and by the subsequent wrench tectonism associated with the San Andreas fault system. Compression normal to the San Andreas in the latest Cenozoic, resulting from changes in relative plate motion, contributed to compressional deformation at the Manuscript approved for publication, November 16, 1988. west side of the valley. Eustatic sea-level effects are less discernible in 1 THE CENOZOIC EVOLUTION OF THE SAN JOAQUIN VALLEY, CALIFORNIA the Neogene, but a middle Miocene highstand probably contributed to the Franciscan Complex along a boundary fault termed the widespread transgression at that time. Climate was an important the Coast Range thrust as first proposed by Bailey and factor in basin history only in the latest Cenozoic (late Pliocene and others (1964).
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