--> Abstract: The Offshore Palo Colorado-San Gregorio Fault Zone: A Slivered and Deformed Salinain Block Boundary, by H. G. Greene, N. H. Maher, S. Eittereim, and A. Stevenson; #90920 (1999).

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H. GARY GREENE, Moss Landing Marine Laboratories, Monterey Bay Aquarium Research Institute (MBARI), Moss Landing, CA; NORMAN H. MAHER, MBARI, Moss Landing, CA; STEVE EITTEREIM and ANDY STEVENSON, U.S. Geological Survey, Menlo Park, CA

Abstract: The Offshore Palo Colorado-San Gregorio Fault Zone: A Slivered and Deformed Salinain Block Boundary

New seafloor imagery (Simrad EM300, 30 kHz, swath bathymetric data) obtained by the Monterey Bay Aquarium Research Institute and the U.S. Geological Survey reveals new faults and high resolution physiograpy of the active offshore Palo Colorado-San Gregorio (PCSG) fault zone. In the Monterey Bay region this fault zone is composed of a series of lengthy (nearly 90 km long) parallel NNW-SSE trending fault strands that extend from Aho Nuevo Point to just north of Point Sur. This fault zone is characterized by two distinct throughgoing faults (spaced 2 km apart) that forms the central part of this 4-5 km wide zone. As many as 3 new faults ranging from 10 to 25 km in length were found concentrated along the western boundary of the Salinian block where it is exposed in Monterey and Carmel canyons.

Extensive mass wasting within the center part of Monterey Canyon and fault scarps aligned along the shelf edge define the northern part of the zone (San Gregorion segment). The central part (Carmel Canyon segment) controls the formation of Carmel Canyon and exhibits offset exotic structural blocks and well defined linear fault scarps. Here faults, including the newly discovered San Jose Creek fault, merge with the PC-SG zone. In the south (Palo Colorado segment) the fault zone is defined by deformed and drag folded Cretaceous(?) sedimentary rocks caught up between the two main through-going faults.

Movement along faults of this zone has pulled apart the western margin of the Salinian block. Approximately 60 km of offset has occurred in the displacement of Ascension shelf break from Sur shelf break, both of which trend nearly E-W.

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