Spatiotemporal patterns of distributed slip in southern Owens Valley indicated by deformation of late Pleistocene shorelines, eastern California

Abstract

Abstract High-resolution elevation surveys of deformed late Pleistocene shorelines and new luminescence dating provide improved constraints on spatiotemporal patterns of distributed slip between normal and strike-slip faulting in southern Owens Valley, eastern California. A complex array of five subparallel faults, including the normal Sierra Nevada frontal fault and the oblique-normal Owens Valley fault, collectively form an active pull-apart basin that has developed within a dextral transtensional shear zone. Spatiotemporal patterns of slip are constrained by post–IR-IRSL (post-infrared–infrared stimulated luminescence) dating of a 40.0 ± 5.8 ka highstand beach ridge that is vertically faulted and tilted up to 9.8 ± 1.8 m and an undeformed suite of 11–16 ka beach ridges. The tectono-geomorphic record of deformed beach ridges and alluvial fans indicates that both normal and dextral faulting occurred between the period of ca. 16 and 40 ka, whereas dextral faulting has been the predominant style of slip since ca. 16 ka. A total extension rate of 0.7 ± 0.2 mm/yr resolved in the N72°E direction across all faults in Owens Lake basin is within error of geodetic estimates, suggesting extension has been constant during intervals of 101–104 yr. A new vertical slip rate of 0.13 ± 0.04 m/k.y. on the southern Owens Valley fault from deformed 160 ± 32 ka shoreline features also suggests constant slip for intervals up to 105 yr when compared to paleoseismic vertical slip rates from the same fault segment. This record supports a deformation mechanism characterized by steady slip and long interseismic periods of 8–10 k.y. where the south-central Owens Valley fault and Sierra Nevada frontal fault form a parallel fault system.