Abstract

New total fault slip estimates for the central Mojave Desert portion of the Eastern California shear zone support through-going dextral shear of ∼18 km that is transferred northward to the Garlock fault. The Eastern California shear zone accommodates ∼25% of the plate-boundary shear, with the transversely oriented Garlock fault forming its northern boundary with the Walker Lane belt. Total fault slip estimates for the major faults in the central Mojave Desert were determined using detailed geologic mapping supplemented with aeromagnetic data. Offset data for the Blackwater fault show a consistent 1.8 ± 0.1 km of dextral slip along 55 km of strike length, and they indicate that slip initiated at or after 3.8 Ma. The faults adjacent to the Blackwater fault have dextral slip of: 4.8 ± 0.3 km (Harper Lake fault); 2.9 ± 0.5 km (Mount General fault); 1.0 ± 0.7 km (Lockhart fault); and 3.2 ± 0.3 and 0.53 ± 0.05 km (Paradise fault). These slip data augment published data for the central Mojave Desert and allow evaluation of the strain path in the central Mojave Desert, showing consistent along-strike, through-going dextral slip. Contractional and extensional step-overs in the central Mojave Desert accommodate a change from focused slip in the southern central Mojave Desert to a wider and more dispersed fault system northward with a shift in the locus of dextral shear westward. We interpret these changes in the fault system to be a response to the Garlock fault, which inhibits through-going faulting but allows through-going dextral shear via clockwise deflection of its trace.

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