Abstract

Several well-dated stratigraphic markers permit detailed assessment of the temporal and spatial variation in slip rates along the interconnected faults of the Fish Lake Valley, Emigrant Peak, and Deep Springs fault zones in west-central Nevada and east-central California. Right-lateral motion on the Fish Lake Valley fault zone apparently began ca. 10 Ma (11.9–8.2 Ma). Associated extensional faulting probably began ca. 5 Ma (6.9–4 Ma) and resulted in the opening of Fish Lake Valley and Deep Springs Valley.

The long-term lateral-slip rate for the Fish Lake Valley fault zone since about 10 Ma is 5 mm/yr (3–12 mm/yr). Our preferred lateral-slip rate for the central, most active part of the Fish Lake Valley fault zone decreased from about 6 to 3 mm/yr from the late Miocene to the early Pleistocene, increased to about 11 mm/yr during the middle Pleistocene, and decreased to about 4 mm/yr during the late Pleistocene. Extension may account for some of the change in lateral-slip rate during the Pliocene. The large increase in lateral-slip rate during the middle Pleistocene is circumstantially linked to an increase in vertical-slip rates on the Fish Lake Valley and Deep Springs fault zones at about the time of the eruption of the Bishop ash (0.76 Ma). Vertical-slip rates along the three fault zones are also related to fault strike; vertical rates are highest on north-striking faults and approach zero on northwest-striking faults.

The long-lived slip history of the Fish Lake Valley fault zone fits a tectonic model in which the Death Valley–Furnace Creek–Fish Lake Valley fault system is integrated with right-lateral shear on faults of the central Walker Lane and the Eastern California shear zone to accommodate part of the Pacific–North American relative plate motion. Our research demonstrates that the Fish Lake Valley fault zone accounts for about half the rate of 10–12 mm/yr of Pacific-North American plate-boundary shear accommodated within the Basin and Range province between about lat 37° and 38°N.

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