FAULT SLIP RATES ON THE NORTHERN DEATH VALLEY FAULT ZONE AND EASTERN CALIFORNIA SHEAR ZONE KINEMATICS

The Northern Death Valley fault zone is thought to accommodate 3 - 8 mm/yr of the approximately 9 mm/yr of relative Pacific-North America plate boundary motion in the eastern California shear zone, north of the Garlock fault.  Although slip rates in the region are well constrained geodetically, there has been limited quantitative geochronology with which to compare the short-term geodetic rates to intermediate- and long-term geologic slip rates along the fault system.  As a consequence, the Northern Death Valley fault zone remains as the largest major missing piece to the geologic versus geodetic slip rate “puzzle” in the northern-half of the eastern California shear zone.  We are using the accumulation of in-situ cosmogenic ¹⁰Be measured in quartzite clasts and high-resolution (sub-meter) LiDAR digital topographic data to generate slip rates at a variety of time scales at several locations along the fault zone.  Cosmogenic nuclide samples were collected from boulder-sized quartzite clasts on the dextrally-offset alluvial fans, such as the one at Red Wall Canyon, in central Death Valley.  By restoring offset alluvial channels in LiDAR images to their original, pre-faulting positions, the amount of displacement during mid-Pleistocene to Holocene time can be resolved.  Geologic slip rates based on the age and displacement of the offset surfaces will be presented.  Comparison of these slip rates with geologic slip rates on other major faults (e.g. Owens Valley, Saline Valley-Hunter Mountain, Ash Hill, etc.) at similar latitudes will allow us to determine the constancy, or non-constancy, of strain release in the eastern California shear zone at a wide range of time scales.  Determining a slip rate budget north of the Garlock fault has implications for the occurrence and locations of strain transients along major plate boundaries, such as those suggested for the Mojave section of the eastern California shear zone.  Once we know precise slip rates on all major faults we can identify whether transient strain accumulation is characteristic of the entire plate boundary or alternatively, the result of local complexities such as the Big Bend of the San Andreas fault.