Tectonic Controls on Stratigraphy and Sedimentology of Pliocene-Pleistocene Lake Tecopa Beds, southeastern California

The Great Basin Pliocene-Pleistocene Lake Tecopa in southeastern California formed in part due to dammming of the ancestral Amargosa River by an antiformal uplift known as the Tecopa Hump. Previous studies concluded that tectonic processes were inconsequntial to lake deposition. Here four stratigraphic sections are measured, described, and compared to sections previously done throughout the basin to discern tectonic influences on lake processes. The southern Tecopa Basin is characterized by a tectonically controlled fan-delta complex intertonguing lacustrine sediments. Joint orientations and bedding attitudes collected on three time horizons, the Lava Creek B tuff (665 ka), Bishop tuff (758 ka), and the C Tuff (2.1 Ma), suggest at least 50 m of uplift during the Quaternary associated with highly variable stress field perturbations. Rising lake level most likely competed with uplift such without uplift lake spillover into southern Death Valley would have occured earlier