Kinematic evidence for extensional unroofing of the Franciscan Complex along the Coast Range Fault, Northern Diablo Range, California

Tectonics
By: , and 

Links

Abstract

Franciscan metagraywacke immediately below the Del Puerto ophiolite, an outlier of the Coast Range ophiolite in the northern Diablo Range, was sheared during top‐to‐the‐east displacement on the Coast Range fault. This represents normal faulting and extensional offset. It was accompanied by attenuation of the Coast Range ophiolite and Great Valley sequence in the hanging wall along layer‐parallel normal faults that sole into the Coast Range fault. Extension occurred as the Franciscan Complex moved relatively west, out from under North American lithosphere and across the subducting ocean plate below. This effected a lengthening and thinning in the wedge of material above the down‐going plate, presumably in response to instability brought about by subduction shallowing (Krueger and Jones, 1989) and accretion of the Franciscan Central belt in the latest Cretaceous to early Paleocene. As a result, blueschist facies terranes of the uppermost part of the Franciscan Complex are now juxtaposed directly against hanging wall units that bear only low‐grade metamorphism.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Kinematic evidence for extensional unroofing of the Franciscan Complex along the Coast Range Fault, Northern Diablo Range, California
Series title Tectonics
DOI 10.1029/91TC01880
Volume 11
Issue 2
Year Published 1992
Language English
Publisher American Geophysical Union
Contributing office(s) Geology, Minerals, Energy, and Geophysics Science Center
Description 14 p.
First page 228
Last page 241