Felsic gneiss, mafic gneiss, orthogneiss, and calc-silicate rock; Early Proterozoic metamorphic rocks; central Idaho; Pioneer Mountains metamorphic core complex (IDXmh;0)

State	Idaho
Name	Felsic gneiss, mafic gneiss, orthogneiss, and calc-silicate rock; Early Proterozoic metamorphic rocks; central Idaho; Pioneer Mountains metamorphic core complex
Geologic age	Early Proterozoic
Original map label	PC
Comments	Xmh is Early Proterozoic high-grade metamorphic gneiss complex of Wildhorse Creek, exposed in the Pioneer Mountains metamorphic core complex. It consists of mostly of quartzofeldspathic gneiss, with subordinate quartz monzonite orthogneiss, mafic gneiss, and calc-silicate marble. Preliminary Rb-Sr data indicate an Early Proterozoic age of about 2 Ga for the complex (ID069).
Primary rock type	felsic gneiss
Secondary rock type	mafic gneiss
Other rock types	orthogneiss; calc-silicate rock
Lithologic constituents	Major Metamorphic > Gneiss (Amphibolite)quartzofeldspathic gneiss Minor Metamorphic > Gneiss (Amphibolite)hornblende-rich mafic gneiss after mafic intrusions Incidental Metamorphic > Gneiss (Amphibolite)orthogneiss after quartz monzonitic intrusions
Map references	Bond, J.G., Kauffman, J.D., Miller, D.A., and Venkatakrishnan, Ramesh, 1978, Geologic map of Idaho: Moscow, Idaho, Idaho Bureau of Mines and Geology, with contributions from U.S. Geological Survey, scale 1:500,000.
Unit references	Bond, J.G., Kauffman, J.D., Miller, D.A., and Venkatakrishnan, Ramesh, 1978, Geologic map of Idaho: Moscow, Idaho, Idaho Bureau of Mines and Geology, with contributions from U.S. Geological Survey, scale 1:500,000. Rember, W.C. and Bennett, Earl H., 1979, Geologic map of the Hailey quadrangle, Idaho: Moscow, Idaho, Idaho Bureau of Mines and Geology, Geologic Map Series, Hailey 2o quadrangle, scale 1:250,000. Dover, J.H., 1983, Geologic map and sections of the central Pioneer Mountains, Blaine and Custer Counties, central Idaho: U.S. Geological Survery Miscellaneous Investigations Series Map I-1319, 1 sheet, scale 1:48,000.
Geographic coverage	Blaine - Custer