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Basin Inversion and the Tectonic Evolution of Borderland Strike-Slip Restraining Bends

Legg, Mark R.*1; Kamerling, Marc J.2
(1) Legg Geophysical, Huntington Beach, CA.
(2) Venoco, Inc., Carpinteria, CA.

Evolution of the Pacific-North America transform fault plate boundary in southern California has produced many strike-slip basins that hold major hydrocarbon accumulations. The complex tectonic evolution from Mesozoic and early Tertiary subduction to Neogene transtension and transrotation followed by late Cenozoic right-slip and transpression resulted in the structural inversion of Miocene basins. We have developed a model that explains the basin inversion as a result of changing relative plate motion vectors where sets of right-stepping dextral transform faults created during oblique-rifting of the Inner Borderland became major strike-slip restraining bends. A system of right-stepping en echelon dextral transform faults linking pull-apart basins created by oblique-rifting of the Inner Borderland became major strike-slip restraining bends subsequent to clockwise shifts in the relative plate motion vector. Transpression at these bends involving oblique-reverse faulting and fault-normal shortening inverted the strike-slip basins into major pop-up structures such as Santa Catalina Island and the Wilmington Anticline. Continued dextral shear along the plate boundary was accommodated by formation of new transform faults that bypass the “locked” restraining bends, a process that continues at present with the increasing activity of the Eastern California Shear Zone to bypass the Big Bend of the San Andreas fault.

 

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California