GSA Connects 2021 in Portland, Oregon

Paper No. 152-4
Presentation Time: 9:00 AM-1:00 PM


LUDWIG, Katherine, Department of Geological Sciences, University of Missouri, Columbia, MO 65211, BIDGOLI, Tandis, Department of Geological Sciences, University of Missouri, 101 Geology Building, Columbia, MO 65211, GOMEZ, Francisco, Department of Geological Sciences, University of Missouri - Columbia, Columbia, MO 65203, WALKER, J. Douglas, University of Kansas, Department of Geology, 1420 Naismith Dr., Lawrence, KS 66045 and STOCKLI, Daniel, Department of Geological Sciences, University of Texas at Austin, Jackson School of Geosciences, Austin, TX 78712

The tectonic environment of southeastern California is characterized by the interactions of the Basin and Range province, the Mojave Block, and the Eastern California shear zone (ECSZ), creating a region with a complex history of deformation. This study explores (1) the Late Cretaceous to Pliocene exhumation history of the footwall of the Kingston Range—Halloran Hills detachment system within this complex structural region, as well as (2) the age and provenance of sediments within the hanging wall of the detachment, to constrain the post-extensional history of strike-slip deformation in the ECSZ. We report apatite and zircon (U-Th)/He data from 22 samples of Proterozoic gneiss and Neoproterozoic to Middle Cambrian metasedimentary rocks collected from two transects in the footwall of the Kingston Range-Halloran Hills detachment in the Kingston and Mesquite ranges. An additional two samples were analyzed from a transect across the 12.4 Ma Kingston Peak pluton. Zircon (U-Th)/He mean ages from the Mesquite Range vary from 14.8 ± 2.1 to 101.5 ± 8.4 Ma; whereas apatite ages range from 11.2 ± 0.5 to 36.3 ± 11.2 Ma. In the Kingston Range, zircon mean ages range from 64.2 ± 7.8 to 171.9 ± 48.3 Ma, while apatite ages range from 18.6 ± 5.6 to 44.0 ± 2.6 Ma. Although samples show some dispersion, likely due to radiation damage effects, ages from these transects increase with distance from the fault. Lastly, two apatite (U-Th)/He ages were obtained for the Kingston Peak pluton. These ages are 7.0 ± 1.6 Ma and 9.3 ± 1.2 Ma, which are in agreement with estimates that the pluton was partially exhumed by ~10-10.5 Ma. The results document two periods of rapid cooling: one in the latest Cretaceous (~65 Ma) and another in the middle to late Miocene. Ongoing work is being conducted and includes inverse modeling of the thermochronology data to better constrain the timing and magnitude of exhumation, detrital zircon U-Pb dating of hanging wall sediments to constrain their ages and likely provenance, and examination of the post-depositional history of the hanging wall in the Avawatz Mountains to constrain the displacement and southern extent of the nearby Southern Death Valley fault.