Attenuation of the Coast Range ophiolite by extensional faulting and nature of the Coast Range "thrust," California

Tectonics
By: , and 

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Abstract

The late Mesozoic Coast Range ophiolite and Great Valley sequence in California were juxtaposed against the Franciscan Complex during a long tectonic history that included imbricate thrust faulting, low‐angle detachment, and high‐angle reverse faulting. Many low‐angle faults previously mapped as thrusts invariably juxtapose younger over older rocks, suggesting a normal sense of offset. We infer that serpentinite melange that is present structurally beneath the Coast Range ophiolite formed above the subduction zone during convergence and was subsequently faulted and further attenuated with upper plate rocks concurrent with extension. Franciscan blueschist‐facies rock is inferred to have been transported from depth to higher structural levels concurrent with underplating and extensional unroofing in the upper plate. The present juxta‐position of the Coast Range ophiolite and Great Valley sequence with Franciscan rocks is commonly controlled by Neogene high‐angle faults. We propose that the term Coast Range thrust is no longer appropriate and that the name should be changed to Coast Range fault.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Attenuation of the Coast Range ophiolite by extensional faulting and nature of the Coast Range "thrust," California
Series title Tectonics
DOI 10.1029/TC006i004p00475
Volume 6
Year Published 1987
Publisher American Geophysical Union
Contributing office(s) Geology, Minerals, Energy, and Geophysics Science Center
Description 14 p.
First page 475
Last page 488
Country United States
State California