Constraints on timing of deformation in the Benton Range, southeastern California, and implications to Nevadan orogenesis

Lower Paleozoic-(?) Precambrian miogeoclinal strata of the Benton Range are deformed into structures whose form and orientation are often associated with the Nevadan orogeny. A swarm of undeformed dikes that postdate folding was intruded between 209 and 168 Ma; thus, major compressional deformation in the Benton Range predates type Nevadan orogenesis by at least 10 m.y. The classic Nevadan and subsequent orogenies did not produce pervasive deformation throughout the eastern parts of the Sierra Nevada and Klamath orogens. A "Nevadan" age cannot be confidently assigned to structures in the western North American Cordillera solely on the basis of their form and/or orientation.