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Evolution of the Coast Range thrust as interpreted from seismic reflection data

Conference · · Geological Society of America, Abstracts with Programs; (United States)
OSTI ID:5099226
 [1]
  1. Onesta Corp., Los Angeles, CA (United States)
The Coast Range thrust is a regional fault system along which the western edge of the Sacramento Valley has been uplifted. Seismic reflection lines which cross this east-dipping fault zone show that the Rumsey Hills and Sites anticlines were formed by severe shortening above the Coast Range thrust, which is the roof thrust of an east-tapering wedge. This wedge consists of Ranciscan rocks at the surface and is underlain by west-dipping Sierran-type granitic rocks, as determined by several wells. A structure contour map of the west-dipping blind thrust beneath the wedge illustrates that it consists of discrete sheets which have propagated northeastward along the crystalline basement and Great Valley Group contact. Unconformities on the western side of the Sacramento Valley illustrate the northeastward progression of deformation above the Coast Range thrust. These unconformities were mapped with seismic and well data and indicate that several thousand feet of uplift occurred in the Rumsey Hills area during Eocene time. Pleistocene rocks are steeply tilted around this structure also, and demonstrate that active underthrusting of the Franciscan wedge is still occurring.
OSTI ID:
5099226
Report Number(s):
CONF-9305259--
Conference Information:
Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 25:5
Country of Publication:
United States
Language:
English

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