--> Abstract: Onshore-offshore Cabrillo Fault, Palos Verdes, California: a Tectonic Fault Associated with the Palos Verdes Fault, by John F. Schwiebert and Robert D. Francis; #90076 (2008)
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Onshore-offshore Cabrillo Previous HitFaultNext Hit, Palos Verdes, California: a Tectonic Previous HitFaultNext Hit Associated with the Palos Verdes Previous HitFaultNext Hit

John F. Schwiebert1 and Robert D. Francis2
110633 Tamarack Way, Stanton, CA 90680-2324
2Department of Geological Sciences, California State University, Long Beach

Our mapping shows that the Cabrillo Previous HitfaultNext Hit (CF) is a steeply NE-dipping tectonic Previous HitfaultNext Hit about 18 km in length on the Palos Verdes Peninsula and adjacent San Pedro Shelf. A previously proposed landslide origin for the Previous HitfaultNext Hit is precluded by the fact that the Previous HitfaultNext Hit continues offshore beyond the area proposed for the slide. The segment of the Previous HitfaultNext Hit trace that is concave to the east, consistent with a landslide head scarp, is only about 4 km long. We have combined previous onshore mapping of the CF (based largely on geomorphic evidence), early 20th century beach-cliff photography (correlated to GPS data using man-made reference points), intertidal outcrops, near-shore side scan sonar, offshore aerial photography, and offshore multibeam bathymetry (USGS) and seismic reflection data. These datasets provide a continuous map of this onshore-offshore Previous HitfaultNext Hit trace, with a gap of only about 300 m at the shoreline, and with both terminations of the CF well delineated. The CF begins near the center of the Peninsula, about 1 km southeast of the oldest rock exposures (Mesozoic Catalina Schist) and strikes about S50E, sub-parallel to the Palos Verdes Previous HitfaultTop (PVF) to the east, and terminating or merging with the PVF adjacent to a short, 1.7 km releasing segment of the PVF about 11 km offshore. The CF runs more or less along the axis of the Palos Verdes anticlinorium, where it appears to truncate various Miocene and Pliocene units, as well as numerous fold axes. These and other features support a dominantly strike slip separation with a possible dip-slip component, which is similar to that documented for the PVF. This and the CF termination near the 1.7 km releasing PVF segment suggest that the two faults are closely related.


AAPG Search and Discovery Article #90076©2008 AAPG Pacific Section, Bakersfield, California