Older rhyolitic flows and shallow intrusive rocks

Includes rhyolitic lava of Portuguese Mountain in northern Nye County, rhyodacite in Elko Hills in Elko County, and other unnamed units. The rhyodacite in Elko Hills was shown on the 1978 State map as unit Tr1, and on the Elko County map as the Jurassic Frenchie Creek Rhyolite. It was subsequently renamed the Rhyodacite of Elko Mountain (Ketner, 1990) when the late Eocene radiometric age of approximately 39.5 Ma was obtained. It corresponds to unit Tr1 on the 1978 State map. This unit is present in northern Nye, Elko, Eureka, and White Pine Counties.
State Nevada
Name Older rhyolitic flows and shallow intrusive rocks
Geologic age lower Oligocene to middle Eocene
Lithologic constituents
Igneous > Volcanic > Felsic-volcanic > Dacite (Flow)rhyodacite
Igneous > Volcanic > Felsic-volcanic > Rhyolite (Flow)
NGMDB product
Counties Elko - Eureka - Nye - White Pine