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Evidence of Northwest-Southeast Directed Compression of Late Cenozoic Age in the Summit Diggings, San Bernardino County, California

MONASTERO, FRANCIS C., and CARL F. AUSTIN, Naval Weapons Center, China Lake, California

Field examination of a low angle thrust fault which strikes essentially east-west at the principal outcrop reveals overthrusting of diotire onto late Pliocene-early Pleistocene fanglomerates. As is typical with the orientation of the trace trend of the fault trace is east-northeast-west-southwest with a south-southeastward dip. This implies general northwest-southeast compression in the late Cenozoic which is contrary to the generally accepted tectonic regime for this area. Four distinct periods of movement on the fault can be distinguished from the outcrop with a minimum throw of 56.4 m. The broad structural fabric in this area has a dramatically different trend than either that found in the northeast portion of the Mojave block or in the Basin and Range block immediately to the nort . It is possible that the compressional features in this area and the different orientation of mesoscale structures are reflections of the fact that compensation is being made in the crust for differential motions between Mojave and Basin and Range microplates.


AAPG Search and Discovery Article #91009©1991 AAPG-SEPM-SEG-SPWLA Pacific Section Annual Meeting, Bakersfield, California, March 6-8, 1991 (2009)