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Koipato Group and related rocks

KOIPATO GROUP AND RELATED ROCKS (Lower Triassic)-Altered andesitic flows, rhyolitic tuffs and flows, and clastic rocks. Includes rocks mapped by Silberling (1959) as Pablo Formation and originally considered to be Permian in the Shoshone Mountains, Nye County. Includes Tallman Fanglomerate (Permian?) in Humboldt County
StateNevada
NameKoipato Group and related rocks
Geologic agePermian to Early Triassic
Original map labelTRk
CommentsThe Limerick Greenstone is 1000-6000 feet thick; the Rochester Rhyolite is upto 6000 feet thick; the Weaver Rhyolite is about 2000 feet thick; the China Mountain Formation is upto 1000 feet thick (Johnson, 1977).
Primary rock typerhyolite
Secondary rock typeandesite
Other rock typesclastic; basalt
Lithologic constituents
Major
Igneous > Volcanic > Mafic-volcanic > Andesite (Flow)Locally metamorphosed to greenstone and albitized to keratophyre.
Igneous > Volcanic > Felsic-volcanic > Rhyolite (Pyroclastic, ash-flow)
Minor
Sedimentary > Clastic (Tuffaceous)Includes volcaniclastic rocks, and tuffaceous conglomerates, siltstones, and sandstones. Possibly only incidental in rank (5% of Rochester Rhyolite for example, but shows up in upper Weaver Rhyolite, as major lithology of China Mountain Formation, and outcrops in Humboldt and Nye Counties).
Igneous > Volcanic > Felsic-volcanic > Rhyolite (Flow)
Incidental
Igneous > Volcanic > Mafic-volcanic > Basalt (Flow)Locally metamorphosed to greenstone and albitized to keratophyre.
Igneous > Volcanic > Mafic-volcanic > Andesite (Volcaniclastic, volcanic breccia)Possible minor in rank.
Map references
Stewart, J.H., and Carlson, J.E., 1978, Geologic Map of Nevada: U.S. Geological Survey and Nevada Bureau of Mines and Geology, 1:500,000 (not part of any formal series, printed and distributed by the U.S. Geological Survey, G75163, reprinted, 1981, G81386).
Unit references
Stewart, J.H., and Carlson, J.E., 1978, Geologic Map of Nevada: U.S. Geological Survey and Nevada Bureau of Mines and Geology, 1:500,000 (not part of any formal series, printed and distributed by the U.S. Geological Survey, G75163, reprinted, 1981, G81386).
Willden, R., 1964, Geology and Mineral Deposits of Humboldt County, Nevada: Nevada Bureau of Mines and Geology Bulletin 59, 154 p., 3 pl.
Johnson, M.G., 1977, Geology and Mineral Deposits of Pershing County, Nevada: Nevada Bureau of Mines and Geology Bulletin 89, 115 p., 4 pl.
Kleinhampl, F.J., and Ziony, J.I., 1985, Geology of Northern Nye County, Nevada: Nevada Bureau of Mines and Geology Bulletin 99A, 172 p., 2 pl.
Geographic coverageChurchill - Humboldt - Lander - Nye - Pershing

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