The Death Valley‐Fish Lake Valley fault zone (DV‐FLVFZ) is a prominent dextral fault system in the eastern California shear zone (ECSZ). Combining offset measurements determined with LiDAR topographic data for two alluvial fans with terrestrial cosmogenic nuclide 10Be ages from the fan surfaces yields a late Pleistocene slip rate of ∼2.5 to 3 mm/yr for the northern part of the DV‐FLVFZ in Fish Lake Valley. These rates are slower than the late Pleistocene rate determined for the system in northern Death Valley, indicating that slip rates decrease northward along this major fault zone. When summed with the slip rate from the White Mountains fault, the other major fault in this part of the ECSZ, our results suggest that either significant deformation is accommodated on structures east of Fish Lake Valley, or that rates of seismic strain accumulation and release have not remained constant over late Pleistocene to Holocene time.

The eastern California shear zone (ECSZ) and Walker Lane represent an evolving segment of the Pacifi c-North America plate boundary in the western United States. Understanding temporal variations in strain accumulation and release along plate boundary structures is critical to assessing how deformation is accommodated throughout the lithosphere. Late Pleistocene displacement along the Lone Mountain fault suggests that the Silver Peak-Lone Mountain (SPLM) extensional complex is an important structure in accommodating and transferring strain within the ECSZ and Walker Lane. Using geologic and geomorphic mapping, differential global positioning system surveys, and terrestrial cosmogenic nuclide (TCN) geochronology, we determined rates of extension across the Lone Mountain fault in western Nevada. The Lone Mountain fault displaces the northwestern Lone Mountain and Weepah Hills piedmonts and is the northeastern component of the SPLM extensional complex, a series of down-to-thenorthwest normal faults. We mapped seven distinct alluvial fan deposits and dated three of the surfaces using 10 Be TCN geochronology, yielding ages of 16.5 ± 1.2 ka, 92 ± 9 ka, and 137 ± 25 ka for the Q3b, Q2c, and Q2b deposits, respectively. The ages were combined with scarp profi le measurements across the displaced fans to obtain minimum rates of extension; the Q2b and Q2c surfaces yield an extension rate between 0.1 ± 0.1 and 0.2 ± 01 mm/yr and the Q3b surface yields a rate of 0.2 ± 0.1-0.4 ± 0.1 mm/yr, depending on the dip of the fault. Active extension on the Lone Mountain fault suggests that it helps partition strain off of the major strike-slip faults in the northern ECSZ and transfers deformation to the east around the Mina defl ection and northward into the Walker Lane. Combining our results with estimates from other faults accommodating dextral shear in the northern ECSZ reveals an apparent discrepancy between short-and long-term rates of strain accumulation and release. If strain rates have remained constant since the late Pleistocene, this could refl ect transient strain accumulation, similar to the Mojave segment of the ECSZ. However, our data also suggest a potential increase in strain rates between ca. 92 ka and ca. 17 ka, and possibly to present day, which may also help explain the mismatch between long-and short-term rates of deformation in the region.

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