Using geologic mapping to understand temporal and spatial relations of closely clustered to concurrent latest Holocene surface ruptures on two intersecting faults, south-central Mojave Desert, California

Abstract

The Pinto Mountain Fault Zone (PMFZ) marks a major structural boundary between east-oriented sinistral faults of the eastern Transverse Ranges (to the south) and northwest-oriented dextral faults of the south-central Mojave Desert (to the north). These structural fault systems comprise sinistral and dextral deformational domains of the Eastern California Shear Zone (ECSZ) that intersect one another in the Copper Mountain and Twentynine Palms areas. The U.S. Geological Survey (USGS) is conducting detailed geologic mapping and geochronologic investigations designed to clarify geometric, kinematic, and temporal relations among the two domains, that are focused on the central portion of the left-lateral PMFZ near its intersection with the right-lateral Copper Mountain Fault (CMF) and Mesquite Lake Fault Zone (MLFZ).