Fault System Evolution, Reactivation and Basin Formation during the Late Cenozoic in the Western Great Basin

Scott R. Kerstetter, The University of Texas at Dallas
David T. Katopody, The University of Texas at Dallas
John S. Oldow, The University of Texas at Dallas

An array of WNW- and NNE-striking faults connects the NW-trending northern Eastern California shear zone and central Walker Lane. The faults syndepositionally controlled the spatial distribution and thickness of three volcanic and sedimentary sequences that record the degree of kinematic linkage between faults and reactivation during three episodes of extension in the late Cenozoic. In the early to mid-Miocene, a 40 km long and 4 to 6 km wide system of WNW-trending half-grabens developed under north-south extension and controlled the deposition of a sequence of andesite and sedimentary rocks. WNW-striking normal faults bounded the half-grabens to the north and south, and juxtaposed asymmetric wedges of basin-fill up to 1500 m thick with Paleozoic metasediments and Mesozoic pluton. NNE- to NS-striking transfer faults segmented the half-grabens and accommodated an 8 km long dog-leg step in the basin system. Between 12 to 4 Ma, reactivated WNW- and NNE-striking faults formed the boundaries of NNE-trending half-grabens that developed in the upper plate of a northwest-dipping, low-angle normal fault. NNE-striking faults were reactivated as normal faults that formed the east and west boundaries of asymmetric basins that controlled deposition of a mid-Miocene to Pliocene sequence of tuff, lava flows, and sedimentary rocks that exhibit a maximum thickness of 2250 m. WNW-striking faults that were reactivated as strike-slip faults accommodated differential displacement between the NNE-trending basins in the upper plate of the detachment. Beginning at 4 Ma, NNE-striking normal faults reorganized into their present configuration as splays off of a single WNW-trending sinistral transcurrent fault that stretches 60 km to the east from the Fish Lake Valley fault of the Eastern California shear zone. NNE-striking normal faults localize the deposition of a Pliocene to Holocene succession of fluvial and lacustrine sediments, basalt, and overlying alluvial deposits within the contemporary basins.


Cordilleran tectonics