CONSTRAINING SLIP RATES ON THE TOWNE PASS FAULT, NORTHERN DEATH VALLEY NATIONAL PARK, CALIFORNIA

The Eastern California Shear Zone north of the Garlock Fault is comprised of a network of northwest-trending dextral strike-slip (Death Valley, Hunter Mountain, Owens Valley) and oblique-normal (Black Mountain, Panamint) fault system and a series of northeast-trending normal (Towne Pass, Tin Mountain, Eureka Valley, Deep Springs) faults. Previous studies suggest that slip on the dextral fault system is transferred by the NE-trending normal faults. In this framework, the Towne Pass fault, transfers slip between the Panamint-Hunter Mountain-Saline Valley Fault System (PHMS) on the west and the Northern Death Valley-Fish Lake Fault System (NDVFL) on the east.

Recent tectonic geomorphic studies show that slip rate varies along sections of the NDVFL from 2.1 mm/y (southeast), 4.3 mm/y and 6.1 mm/y (center), and 2.5mm/y (northwest). The NE-trending normal faults span between the PHMS and NDVFL systems where the elevated slip rates on the NDVFL are found, which supports the slip transfer hypothesis. Geomorphic or relative-age slip estimates are available for a few of these faults, but none of them have employed modern geochronological means to date the geomorphic features that are offset by these faults.

Here we present preliminary results from our neotectonic study of the Towne Pass fault (TPf). The TPf forms scarps in Quaternary alluvial fan deposits near Emigrant Canyon Road and juxtaposes limestone bedrock and Quaternary fan deposits, making the fault an ideal target for a detailed analysis of slip rates and recurrence intervals. We collected cosmogenic ³⁶Cl surface exposure samples on the limestone scarps and ¹⁰Be exposure samples from the offset fans during the spring of 2016. We will present preliminary estimates of alluvial fan surface age, number of earthquakes, slip rates, and recurrence intervals for the TPf. Results from this study will elucidate the efficiency of slip transfer by the NE-trending normal faults.