Late Cenozoic Deformation in the Coso Range, Eastern California, and Relation to the Coso Geothermal and Magmatic Systems

摘要

Fluid circulation in the Coso geothermal system is governed by active movements in the dextral Airport Lake--Owens Valley (ALOV) fault zone. Two new observations lead to reexamination of the hypothesis that a right step-over in a still-developing fault zone localizes the geothermal system: (1) the ALOV fault zone proves to be a long-lived crustal boundary that accommodated 65 km of dextral slip since Late Cretaceous time, and (2) the Cretaceous Coso dike swarm may continue largely undisrupted across the location of the proposed step-over. Alternative models that may account for Coso Range faulting include block rotation, partitioning of dip- and strike-slip faulting, and faulting driven by magmatic intrusion. Plio-Pleistocene magmatic intrusion may have been the cause, rather than the result, of the structural complexity of the Coso Range segment of the ALOV fault zone.