Tectonic inheritance from deformation fabric in the brittle and ductile Southern California crust Journal Article uri icon

Overview

abstract

  • Plate motions in Southern California have undergone a transition from; compressional and extensional regimes to a dominantly strike-slip regime; in the Miocene. Strike-slip motion is most easily accommodated on; vertical faults, and major transform fault strands in the region are; typically mapped as near-vertical on the surface. However, some previous; work suggests these faults have a dipping or listric geometry at depth.; We analyze receiver function arrivals that vary harmonically with; backazimuth at all available broadband stations in the region. The; results show a dominant signal from contrasts in dipping foliation as; well as dipping isotropic contrasts from all crustal depths, including; from the ductile middle to lower crust. We interpret these receiver; function observations as a dipping fault-parallel structural fabric that; is pervasive throughout the region. The strike of these structures and; fabrics is parallel to that of nearby fault surface traces. We also plot; microseismicity on depth profiles perpendicular to major strike-slip; faults and find consistently NE-dipping lineations in seismicity; shallowing in dip from near vertical (80-85) on the Elsinore Fault near; the coastal ranges to 60-65 slightly further inland on the San Jacinto; Fault to 50-55 on the San Andreas Fault. Taken together, the dipping; features in seismicity and in rock fabric suggest; that preexisting fabrics and faults likely act as strain guides in the; modern slip regime, with reactivation-like mechanisms operating both; above and below the brittle-ductile transition.

publication date

  • February 6, 2020

has restriction

  • closed

Date in CU Experts

  • November 9, 2020 2:06 AM

Full Author List

  • Schulte-Pelkum V; Ross ZE; Mueller K; Ben-Zion Y

author count

  • 4

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