SUMMATION OF DISTRIBUTED SLIP ACROSS THE WALKER LANE

Continental strike-slip plate boundaries tend to accommodate slip through a complex network of faults that evolve over time. Observations along some fault systems suggest a discrepancy between long- and short-term slip rates, which must be attributed to fluctuations in strain over time, broadly distributed strain, and/or an incomplete geologic record. We investigate such a discrepancy in the Walker Lane, a dextral shear zone in eastern California and western Nevada that participates in the Pacific-North America plate boundary and acts as the transition between the Basin and Range province and the Sierra Nevada block. Our observations include GPS time series, high-resolution lidar topography and field mapping of offset landforms, and ¹⁰Be cosmogenic nuclide exposure ages. Taken together, these observations show that: 1) the Walker Lane currently accommodates 9.7±0.3 mm/yr of right-lateral motion toward N37°W; 2) slip is very evenly distributed across the entire shear zone; 3) extension in the Silver Peak-Lone Mountain extensional complex (SPLM) appears to have increased through the late Pleistocene, while right-lateral slip on the White Mountains Fault appears to have decreased during that same time; 4) long- and short-term extension rate estimates for the SPLM are in agreement; 5) there remains a discrepancy between long- and short-term slip rates that we suggest occurs across Owens Valley. Future work to fully resolve the discrepancy should focus on faults to the west of White Mountains Fault, including Owens Valley Fault, Round Valley Fault, and the faults that offset the Volcanic Tableland.