New Estimates of Late Pleistocene Slip Rate Along the Panamint Valley Fault System: Implications for Distributed Shear in Eastern California

Thursday, 17 December 2015
Poster Hall (Moscone South)
Na Hyung Choi1, Eric Kirby1 and Eric McDonald2, (1)Oregon State University, Corvallis, OR, United States, (2)Desert Research Institute Reno, Reno, NV, United States
Despite decades of study, the distribution of fault slip within the eastern California shear zone (ECSZ) remains incompletely understood. Along the Panamint Valley fault system (PVFS), Late Pleistocene - Holocene slip rates are sparse, limited to a single site along the southernmost fault segment (~2-3 mm/yr). However, geodetic results along the Hunter Mountain fault, a strike-slip fault linked to the northern PVFS, suggest slip rates as high as 5-6 mm/yr. Here, we present preliminary results from an investigation of displaced alluvial fan surfaces along the central PVFS, near Jail Canyon. We utilize LiDAR-derived high resolution topography, field mapping, and soil characterization to reconstruct displacement. Comparison of soil characteristics to a calibrated regional soil chronosequence constrains the age of alluvial surfaces; analysis of a depth profile using 10Be cosmogenic isotopes is underway.

The PVFS near the mouth of Jail Canyon is characterized by a ~500 m wide zone of distributed deformation. Dextral offset of channels and associated alluvial surfaces across a N45W strike-slip fault marks lateral displacement, while N-S striking normal faults accomplish E-W extension. We exploit the preservation of a large relict channel to reconstruct the cumulative displacement from these faults. Offset crests of the channel levees suggest 115±10 m of right-lateral displacement, while the sum of extension across the fault zone is 34±3 m. Together, these suggest a cumulative slip of 148±13m oriented in a 310° direction, consistent with dextral-oblique motion across the PVFS. Soil development in alluvial surfaces is consistent with soils dated regionally between 30 – 50 ka. These preliminary results suggest that a minimum slip rate across the central PVFS is 4.1±1.3 mm/yr. Our results imply that the PVFS accomplishes a greater fraction of dextral shear, north of the Garlock fault, than previously thought.