Magnitude of crustal extension in the southern Great Basin

Abstract

Strike-slip faults in the southern Great Basin separate areas of Cenozoic upper crustal extension from relatively stable tectonic blocks. Linear geologic features, offset along the Garlock fault, Las Vegas Valley shear zone, and Lake Mead fault system, allow reconstruction of the southern Great Basin to a pre-extension configuration. The Sierra Nevada, Mojave Desert, Spring Mountains, and Colorado Plateau are treated as stable, unextended blocks that have moved relative to each other in response to crustal extension, with the Spring Mountains held fixed to the Mojave block. Our reconstruction indicates a minimum of 65% extension (140 km) between the southern Sierra Nevada and Colorado Plateau.