Deep-marine sedimentary rocks
Deep-marine sedimentary rocks
Late Triassic
Chiefly Late Triassic basinal-marine carbonate rocks with interbeds of sedimentary and volcanic rocks. In the Pine Nut Mountains east of the map area, the base of this unit is Early(?) to Late Triassic felsic volcanic rocks. Late Triassic rocks are chert, phyllite, shale, minor carbonate, volcanogenic sedimentary rocks, limestone, quartzite, marl, chert, argillite, slate, quartzite, chert conglomerate, limestone, andesite tuff, tuff breccia.
The age of this unit is constrained by fossils. In the Mount Siegel 15’ Quadrangle, early late Norian and late early Norian fossils from the Oreana Peak Formation near Buffalo Canyon (Silberling, 1984). In the Desert Creek Peak 15’ Quadrangle, late Karnian to earliest Norian fossils in limestone at the northwest end of Pine Grove Hills, east of the map area (Silberling, 1984). In the Topaz Lake 15’ Quadrangle a Late Triassic S<em>eptocardia(?) fossil in the Oreana Peak Formation (isolated exposure too small to show) near Holbrook Junction (Silberling, 1984). Just east of the map area in the Dayton 15’ Quadrangle, early late Norian fossil from marble in Sand Canyon, and a questionable fossil of possible Late Triassic age from marble at Brunswick site (Stewart, 1997).