--> Evolution Of The Palos Verdes Fault Near Lasuen Knoll, Offshore Southern California

Pacific Section AAPG Convention

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Evolution Of The Palos Verdes Fault Near Lasuen Knoll, Offshore Southern California


The Palos Verdes Fault Zone (PVFZ) is a near-vertical, multi-stranded, oblique dextral shear zone that extends from Santa Monica Bay in the north to San Pedro Bay offshore Southern California. It is one of several Inner Borderland northwest-trending faults formed during middle Miocene rifting. Neogene deformation involved dextral slip on the fault and clockwise rotation of crustal blocks, causing tectonic inversion of the San Pedro Basin along the PVFZ. On the San Pedro Shelf, the PVFZ forms a trap for the Beta oil field, which has been estimated to contain recoverable reserves of 590 MMBOE. Recent seafloor expressions of the fault are evident southeast of the San Pedro shelf where the PVFZ forms a transpressional contact at Lasuen Knoll. Several stratigraphic sequences onlapping Lasuen Knoll in seismic data suggest that a complex history of tectonic uplift has formed the knoll. The fault appears to die out or step eastward before slip continues to the Coronado Bank Fault. This study dates tectonic subsidence and uplift along the PVFZ, and analyzes where and how slip on the fault is transferred at its southern extent to the Coronado Bank Fault. Structure and isochore maps of stratigraphic sequences were generated using 3D and 2D deep-penetrating seismic data, 2D high-resolution seismic data, well logs, paleontological reports, and seafloor bathymetry and backscatter imagery. Analysis of these maps provides insight to the sedimentological and structural processes and mechanisms that have acted locally over the lifespan of the basin. This study culminates synthesizing the relationships between the PVFZ, Lasuen Knoll and the Coronado Bank Fault, as well as the effects of Inner Borderland tectonic evolution on the development of this southern segment of the PVFZ.