CONSTRAINTS ON THE SOUTHERN EXTENT OF THE SOUTHERN DEATH VALLEY FAULT FROM DETRITAL ZIRCON U-PB GEOCHRONOLOGY AND BEDROCK (U-TH)/HE THERMOCHRONOLOGY

The southern Death Valley fault (SDVF) is a dextral strike-slip fault that extends south, through Death Valley, and intersects with the left-lateral Garlock fault in the Avawatz Mountains. It has been proposed that Miocene strata in the Avawatz Mountains may be sourced from the Halloran Hills, which are now 20 km to the south, suggesting that the SDVF extends that distance and has accommodated at least an equivalent amount of displacement. This study explores this potential tie through detrital zircon U-Pb provenance analysis of the Military Canyon Formation in the Avawatz Mountains and age-equivalent strata from the Halloran Hills. We also perform zircon (U-Th)/He dating of samples from the northeastern part of the Avawatz Mountains to constrain the timing and rate of exhumation of the range. Detrital zircons U-Pb age spectra for the Military Canyon Formation are dominated by Jurassic and Precambrian (~1800-1500 Ma) ages, consistent with a source in the Avawatz Mountains; whereas our sample from the Halloran Hills is more unimodal, with a dominant peak at ~90 Ma, likely sourced from the nearby Teutonia Batholith. The results demonstrate that these formations are unrelated, and cannot be used as evidence for a continuation of the SDVF. Zircon (U-Th)/He mean ages obtained from six samples in the Avawatz Mountains range from 6.3 ± 1.4 Ma to 74.0 ± 10.7 Ma (2σ), with most samples unreset or only partially reset in the Miocene. Time-temperature history modelling of the new data and published ages will constrain exhumation timing and magnitudes, and will aid in delimiting viable models for a southern extension of the SDFZ.