Through preliminary studies, loci of magmatic transitions (e.g., from high Ba/Nb Steens-like lavas to low Ba/Nb alkalic basalts) have been identified in north central Nevada (near Winnemucca, East of Fallon, and between Kane Springs Wash and the Lunar Crater volcanic field). However, compositions of these magmas could also be influenced by lateral variations in basement (including lithospheric mantle) age and composition. This project will carry out a detailed geochemical study of mafic lavas from roughly north-south and east-west transects across north-central Nevada to evaluate source characteristics. Age determinations will be made for selected samples to establish the chronology of magma source transitions. These data will provide important constraints on mantle involvement during the Cenozoic regional extension of the Cordilleran region.
