Darwin Plateau basalts
Darwin Plateau basalts
early Pliocene to late Miocene
consists of a series of flood-like olivine basalt lava flows and minor interbedded basaltic lapilli tuff and tuff breccia cropping out in the Coso Range and on the Darwin Plateau. Basaltic lavas are olivine-phyric with compositions ranging from calc-alkaline high-alumina basalt to alkali-olivine basalt (Larsen, 1979; Schweig, 1989). Flows range in thickness from 1 m to more than 60 m and are typically areally extensive (Schweig, 1989). Described as more fluid and flood-like compared to Coso volcanic units (map units cov, covy; Jayko, 2009). K-Ar ages range from 7.7 ± 0.5 Ma (Schweig, 1989) to 4.3 ± 0.2 Ma (Larsen, 1979). Sourced at least in part from cinder cones and basaltic dikes in the Rainbow Canyon area (Schweig, 1989).