--> Abstract: Age of Coast Ranges Uplift in Central California, Evidence from the Sedimentary Record of the San Joaquin Basin, by D. D. Miller; #90920 (1999).

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MILLER, DONALD D.
Aera Energy LLC, Bakersfield, CA

Abstract: Age of Coast Ranges Uplift in Central California, Evidence from the Sedimentary Record of the San Joaquin Basin

Late Cenozoic uplift of California's Coast Ranges province is widely attributed to shortening perpendicular to the San Andreas fault as a consequence of oblique convergence of the Pacific and North American Plates. Age estimates for this event based on marine studies range from 3.4 to 6 Ma.

This study presents reflection-seismic data and geohistory analysis based on revised stratigraphic ages that indicate tectonic uplift of the Diablo-Temblor Ranges segment of the southern Coast Ranges probably began about 6 Ma, and no later than 5.4 Ma. The onset of tectonic shortening and uplift clearly preceded the development of angular unconformities and deposition of the Pliocene-Pleistocene Tulare Formation. Conglomeratic and nonmarine sedimentary facies of this unit typically are considered "syn-tectonic", but represent a wedgetop depozone during the latest stage of deformation. These data indicate the lack of a second compressional event during the past 4 m.y., but suggest there was a strong sedimentary overprinting during continuing shortening. The widespread distribution of these coarse-grained nonmarine sediments beginning at about 3.4 Ma is explained by a combination of two mechanisms, and neither is due to the immediate change of Pacific Plate motion.

AAPG Search and Discovery Article #90920©1999 AAPG Pacific Section Meeting, Monterey, California