RESOLVING SPACE-TIME STRAIN PATHS OF THE PANAMINT AND COTTONWOOD MOUNTAINS, EASTERN CALIFORNIA, THROUGH BEDROCK AND DETRITAL THERMOCHRONOLOGY

This study focuses on recovering the history of extensional and strike-slip deformation in the Panamint Valley region, concentrating on the Panamint Range and southern Cottonwood Mountains, west of Death Valley. These ranges and their associated faults are important because they are inferred to have accommodated a significant portion of the Miocene to Pliocene plate boundary strain, inboard of the Sierra Nevada. Although a number of studies have been completed in the region, published displacement vectors for individual ranges are variable and suggest that strain paths are not well resolved. Complicating the picture is the role of earlier deformation, documented in the footwalls of detachments in the region, on reconstructions of the Miocene to Pliocene motion of these ranges.

Here we use a combination of bedrock and detrital (U-Th)/He thermochronology to reconstruct space-time strain paths of the Panamint and Cottonwood mountains. A total of 38 samples were collected from Jurassic to Miocene plutons and stocks in transects and at sites in these ranges. Sampling targets include granitoids of the Skidoo, Hall Canyon, and Manly Peak plutons in footwall of the Panamint-Emigrant detachment (PED) in the Panamint Range, and quartz monzonites of the Hunter Mountain batholith in the southern Cottonwood Mountains, on the north side of the Hunter Mountain fault. Samples were also collected from each of three major basin-filling units of the Nova Basin, in the hanging wall of the PED, that record the late Miocene to Pliocene exhumation history of the range. The bedrock zircon and apatite (U-Th)/He ages will be used to evaluate apparent age versus elevation/paleodepth trends and to explore viable temperature-time histories using inverse modeling approaches. Age data from the Nova Basin will be compared with ages from footwall of the PED to assess similarities and differences in preserved cooling histories and the robustness of basin sediments and double-dating approaches in capturing the exhumation history of a range. Together these analyses will provide independent constraints on the magnitude of cooling, timing of fault initiation, fault slip rates, and geothermal gradients that can be integrated with other geologic datasets to resolve space-time strain paths.