COLLABORATIVE RESEARCH: Studies of Large-Magnitude Intra- continental Extensional Strain, Death Valley Region, California

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Large-magnitude intracontinental extension in the Death Valley region of California has been modeled by using pre-extensional markers such as pre-Tertiary thrust faults and Paleozoic strati- graphic trends. The model indicates that extension across the region was accommodated by wholesale separation of the upper 15 km of the continental crust along a discrete, west-dipping zone of normal faults less than 10 km in width. During the ensuing 150km of pull apart, deep crust rose isostatically and filled the void left between the separating blocks. Volumetrically minor fault slivers were sequentially transferred from the hanging wall block to the detached slivers and apparent cessation of major extension migrated westward with the hanging wall. This project will use structural mapping, paleomagnetism and thermochronology of the slivers to rigorously test this model. Results are of importance to south-western U.S. tectonics and to the general process of large-scale continental extension.