San Nicolas Basin

Slope-failure history in San Nicolas Basin from high-resolution acoustic imaging and core properties, Outer California Borderland

Data: https://doi.org/10.7284/910805

(in prep)

Abstract

The San Nicolas Basin, extending ~80×60 km and oriented N46°W, is aligned sub-parallel to the regional tectonic fabric of the Outer California Borderland, offshore Southern California. The northern margin displays an arcuate geometry, indicative of potential structural control by the East Santa Cruz Basin fault, whereas the relatively straight western margin suggests control by the Ferrelo fault zone. New high-resolution geophysical data acquired during cruise SR2502, including multibeam bathymetry and CHIRP sub-bottom profiles, reveal a complex interplay between tectonic deformation and sedimentary processes shaping the basin floor. Analysis of these datasets has identified at least nine minor, repeated submarine mass transport deposits (MTDs) and one major near-surface landslide, referred to as the San Nicolas slide, interbedded with hemipelagic sediments. These MTDs are interpreted as the result of earthquake-induced slope failure, providing a basis for reconstructing a paleoseismic record since the late Pleistocene. Stratigraphic relationships and temporal patterns of MTD emplacement suggest that both regional fault systems and local sources influenced slope instability. Evidence of MTDs deposition, associated with fault vertical offsets and onlapping contacts, supports a relationship between seismic ground shaking and mass wasting. These preliminary findings highlight the potential for applying turbidity paleoseismology across the Outer California Borderland.