HR: 1340h
AN: T43A-1100    [Abstracts]
TI: 3D Fault Geometry and Basin Evolution in the Northern Continental Borderland Offshore Southern California
AU: * Schindler, C S
EM: sarahschindler@gmail.com
AF: Department of Geology, California State University, Bakersfield, CA 93311,
AU: Nicholson, C
EM: nicholson@msi.ucsb.edu
AF: Marine Science Institute, University of California, Santa Barbara, CA 93106,
AU: Sorlien, C
EM: chris@crustal.ucsb.edu
AF: Marine Science Institute, University of California, Santa Barbara, CA 93106,
AB: Grids of recently released high-quality industry multichannel seismic (MCS) reflection data, combined with bathymetry and offshore well data are used to map digital 3D fault surfaces and stratigraphic reference horizons in the northern Continental Borderland offshore of southern California. This area experienced large-scale oblique crustal extension and translation associated with the initiation and development of the Pacific-North American plate boundary. The 3D surfaces of structure and stratigraphy can thus be used to better understand and evaluate regional patterns of uplift, subsidence, fault interaction and other aspects of plate boundary deformation. Our mapping in Santa Cruz basin and on Santa Rosa and Santa Cruz-Catalina Ridge reveals an unusual pattern of faulting, folding and basin subsidence. This subsidence is significant (up to 3-4 km since early-Miocene time) and is responsible for the development of several major Borderland basins. Vertical motions can be estimated from an early-Miocene unconformity that likely represents a paleo-horizontal, near-paleo-sea-level erosional surface. As such, it can be used to reconstruct Borderland forearc geometry prior to rifting, subsidence and subsequent basin inversion. Major findings to date include: (a) a better characterization of the complex 3D geometry and pinch-out of the eastern edge of the northern forearc Nicolas terrane and its implications for Borderland basin development, plate reconstructions, and vertical motions associated with oblique rifting; (b) recognition that the East Santa Cruz Basin fault, previously thought to be a predominantly high-angle, large- displacement right-slip fault representing the eastern edge of the Nicolas terrane, is in fact a series of reactivated right-stepping, NE-dipping reverse-separation faults; (c) discovery that NW-striking faults associated with Santa Cruz-Catalina Ridge bend west into a horse-tail structure to interact with and contribute to the southern frontal fault system of the Northern Channel Islands anticlinorium; and (d) recognition that both Santa Cruz-Catalina Ridge and the even larger Santa Rosa Ridge represent complex inverted basins resulting from post-Miocene compressional folding.
DE: 3000 MARINE GEOLOGY AND GEOPHYSICS
DE: 8005 Folds and folding
DE: 8010 Fractures and faults
DE: 8038 Regional crustal structure
DE: 8102 Continental contractional orogenic belts and inversion tectonics
SC: Tectonophysics [T]
MN: 2007 Fall Meeting