Evolution of Extensional Basins and Basin and Range Topography West of Death Valley, California

Neogene extension in the Death Valley region, SE California, has produced a variety of sedimentary basins. Diachronous movements on an array of strike-slip and normal fault systems have resulted in the uplift and preservation of older basins in modern ranges. One of the best exposed of these is the Nova basin on the western flank of the Panamint Mountains. The Nova basin includes over 2000 m of sedimentary and volcanic rocks deposited during denudation of the Panamint Mountains metamorphic ore complex in late Miocene (?)early Pliocene time. The principal growth structure for the basin was the Emigrant detachment, which initiated and moved at a low angle. Modern Panamint Valley, west of the range, developed as a consequence of Late Pliocene Recent, kinematically linked movement on the right-slip, high-angle Hunter Mountain fault zone and the low-angle Panamint Valley detachment. Detailed mapping of the intersection between the Emigrant and Panamint Valley detachments demonstrates that segments of the earlier 1 Now at Department ofEarth and Planetary Sciences, Harvard University, Cambridge 2 Now at Geology Institute, Swiss Federal Institute of Technology, Z'tirich, Switzerland 3 Now at Department ofGeology, University of Kansas, Lawrence. Copyright 1989 by the American Geophysical Union Paper number 890TC00015. 0278-7407/89/89TC-00015510.00 system remained active during development of Panamint Valley and, thus, during development of modern Basin and Range topography as well. These results indicate that large-scale extension in the Death Valley region, accommodated by movement on lowto moderate-angle normal fault systems and high-angle strike-slip fault systems, is a continuing process. Basin and Range topography in the Panamint ValleyDeath Valley area was generated at least in part by displacements on low-angle detachments rather than high-angle normal faults.