Remnants of the northern Sierra Nevada Paleozoic island arc in western Nevada

Allochthonous upper Paleozoic volcanic island-are suites of the U.S. Cordillera have previously been interpreted as parts of a single island are. New lithologic, age, structural, biogeographic, and geochemical data indicate the presence at least of two arcs, one built on a basement with continental crustal affinities including that of the Northern Sierra terrane, and the other built on an oceanic basement including that of the Eastern Klamath terrane. In the Garfield Hills, western Nevada, the Lower Permian Black Dike Formation appears to be a remnant of the Northern Sierra Paleozoic island are. It consists of calc-alkaline rocks with low-to-negative epsilon(Nd) ratios. Volcanic rocks share similar ages, magmatic affinities, and epsilon(Nd) ratios with lavas of the Goodhue Formation in the Northern Sierra terrane. Our new data suggest that these rocks are part of the Northern Sierra terrane, and we therefore infer that part of western Nevada was originally underlain by a basement with continental crustal affinities.