Structural and Sedimentologic Evolution of a Miocene Supradetachment Basin, Silver Peak Range and Adjacent Areas, West-Central Nevada

摘要

The Silver Peak region of west-central Nevada provides a unique opportunity to study the history of a supradetachment basin, its deformed basement, and the detachment fault itself. The region experienced Late Cretaceous to Paleogene plutonism and stretching of a Neoproterozoic through Ordovician miogeoclinal section. Upper-crustal thinning above the Mineral Ridge pluton was accommodated by development of gently dipping schistosity in Neoproterozoic strata, and a mosaic of low-angle attenuation faults in overlying Cambrian strata. Middle and Late Miocene detachment faulting accommodated approximately 8-15 km of northwest transport of hanging-wall strata. The Mineral Ridge detachment fault apparently reactivated the basal decollement of the Late Cretaceous to Paleogene attenuation faults. The Esmeralda basin evolved in the hanging wall of the detachment-fault system, and represents subsidence over a significantly broader region than modern extensional basins. The supradetachment basin fill consists of three interfingering lithofacies assemblages: (1) an east-derived, conglomeratic, sedimentaclastic, alluvial-fan assemblage deposited adjacent to the breakaway; (2) mudstone and coal deposited in lacustrine and paludal environments; and (3) a west-derived, sandy, volcaniclastic assemblage deposited in braidplain/braiddelta environments. Geometric relations indicate that the detachment fault dipped gently while active, and was the sole fault for a stack of listric-normal growth faults. Late Miocene arc volcanism within the Silver Peak region postdated cessation of detachment faulting. Present physiography is controlled by Pliocene to Holocene normal and strike-slip faulting associated with volumetrically minor basaltic volcanism. This complex history of late Mesozoic and Cenozoic deformation, magmatism and sedimentation in the Silver Peak region may be analogous to other parts of the Basin and Range Province, suggesting broad applicability of the model developed herein.