Distinct mantle sources for Pliocene-Quaternary volcanism beneath the modern Sierra Nevada and adjacent Great Basin, northern California and western Nevada, USA

Abstract

Latest Pliocene to Quaternary, mildly alkaline, mafic to intermediate volcanic activity extends in a swath from the Lake Tahoe region in the eastern Sierra Nevada across the western Great Basin to the Battle Mountain area, Nevada. From west to east, the volcanic centers exhibit a dramatic gradient in chemical and isotopic composition. Centers situated in or adjacent to the Sierra Nevada have incompatible element and isotopic compositions consistent with an old, subduction-modifi ed lithospheric mantle source(87Sr/86Sr > 0.7045; 143Nd/144Nd < 0.5127; δ18O > +6.5%). Mafi c volcanic centers east of the Sierra Nevada, in the Carson Sink and in the Buffalo Valley region, have an intraplate incompatible element and iso topic signature(87Sr/86Sr < 0.7045; 143Nd/144Nd > 0.5127; δ18O