Abstract: Structural
Transect Across the Eastern Santa Barbara Channel (Western Transverse Range) California
Enrique Novoa, John Shaw, John Suppe
A balanced cross
section combining surface and subsurface data (seismic reflection, boreholes, and existing geologic
maps
) across the eastern part of the Santa Barbara Channel suggests that the
structural
style and evolution of this region are dominated by two south vergent faults, the Channel Islands and Santa Ynez Mountain thrusts. The Channel Islands thrust dips 20° to the north and extends upward from at least 16.5 km depth beneath the Oak Ridge trend, an active fault-bend fold developed in its hanging wall. As the ramp approaches the Channel Islands, it flattens to a negligible dip and wedges back to the north, uplifting the islands that lie in the hanging wall (Shaw and Suppe, 1993). The Santa Ynez Mountain thrust is defined by a north-dipping ramp whose top flattens at abo
t 7 km, immediately north of the Santa Ynez Mountains. Active folds developed above the thrust to the south include the Dos Quadras and Carpinteria trends, which are defined at depth by a complex wedge structure. A small fraction of the total slip on Santa Ynez Mountain thrust is transferred southward where fault-bend folds, such as Pitas Point and Blue Bottle, were generated on Pitas Point thrust (Shaw and Suppe, 1993). A foreword model of the region from Santa Ynez Mountains to south of Santa Cruz Islands illustrates how the structures formed through time, as well as how slip is partitioned between Channel Island and Santa Ynez Mountain thrust systems to produce the complicated structures in the Santa Barbara Channel.
AAPG Search and Discovery Article #90981©1994 AAPG Pacific Section Meeting, Ventura, California, April 27-29, 1994