COMPLEX STRUCTURAL GEOLOGY IN THE INTERSECTION ZONE BETWEEN THE EASTERN GARLOCK, OWL LAKE, AND BROWN MOUNTAIN (PANAMINT VALLEY) FAULTS, SOUTHEAST CALIFORNIA: IMPLICATIONS FOR THE EVOLUTION OF THE GARLOCK FAULT

The eastern Garlock fault forms a complex intersection with the left-lateral Owl Lake fault and the right-lateral Brown Mountain fault in the vicinity of the Quail Mountains and Fort Irwin. In this area, there are distinct fault populations of varying relative age and slip sense. The structural geology of this intersection zone has implications for the evolution of the Garlock fault relative to surrounding structures of Walker Lane and the Eastern California Shear Zone. Within the intersection, there are NW-SE striking right-lateral faults, NE-SW and E-W striking left-lateral faults, and north dipping reverse faults, with few clear cross-cutting relations. Relative age between faults can be assessed from the youthfulness of topographic landforms, the relative age of faulted surfaces, and degradation modeling of fault scarps. The youngest fault populations appear to be the portions of the Garlock fault east of the intersection zone, while the oldest faults appear to be the right-lateral faults associated with the Panamint Valley / Brown Mountain fault and the north-dipping reverse faults. These relationships suggest a composite deformation history, with roughly coeval deformation along right and left-lateral faults. Coordinated slip on the Panamint Valley and Owl Lake faults may have caused the reverse faulting and the Garlock fault later propagating towards the east. Better constraints on the absolute timing of these various fault sets should help establish the timing of events in this intersection and the overall relationship between the Garlock, Owl Lake, and Panamint Valley / Brown Mountain faults.