Pennsylvanian to Cretaceous folds and thrusts in south-central Nevada: evidence from the Timpahute Range

Understanding Permian and Mesozoic contractional structures from southern California to northern Nevada requires correlation through south-central Nevada. After the Devonian-Mississippian Antler orogeny through the Permian-Triassic Sonoma orogeny and then up to the Sevier orogeny, south-central Nevada was thought to have remained tectonically inactive. However, Pennsylvanian through Jurassic age deformation is documented to the south in Death Valley and to the north. Identifying geometries, spatial relationships, and relative timing of deformations in the Timpahute Range, south-central Nevada, is an essential piece to completing the overall understanding of Nevada geology. The purpose of this study is to identify and analyze deformational structures of the Timpahute Range and clarify their geometries, relative timing, regional correlation, and tectonic significance. All contraction in the Timpahute Range is constrained by Antler foreland basin units and the intrusion of the 102.9 ± 3.2 Ma Lincoln stock. New mapping at a scale of 1:12,000 documents three contractional episodes in the Timpahute Range, and cross-cutting relations from this study determine at least a relative timeline. The Tempiute Ridge Block contains a W-vergent fold that represents the earliest contractional event in the area. Next was the W-vergent Schofield Pass fault zone. The last contractional deformation formed E-vergent structures of the Central Nevada thrust belt which make up the Lincoln duplex. In collisional orogens, closely related thrust faults may join together in a fault system that includes such structures such as imbricate fans and duplexes. The Lincoln duplex, part of the Central Nevada thrust belt exposed in the Timpahute Range and southern Worthington Mountains, consists of folds and a sequence of thrust faults. New data suggest the Lincoln duplex is a variation of the hinterland dipping duplex, with out-of-sequence thrusts. Cenozoic extensional faults overprint the contractional structures. A series of NW-striking normal faults terminate at a major ENE-striking left-lateral strike-slip fault. This fault continues eastward through multiple ranges in south-central Nevada as part of the Timpahute lineament