Idaho batholith and associated masses (MTKi;0)

Idaho batholith and associated masses: faintly gneissic quartz monzonite, granodiorite, and similar rocks. The extreme eastern part of the Idaho batholith extends into Ravalli County, Mont. This and nearby masses of similar rocks are shown as associated with the Idaho batholith and designated Ki. Future studies may show that some granitoid masses further east are also allied to the Idaho batholith or that a few of the masses now grouped with that batholith are younger. Precise dating is impossible at present.

State	Montana
Name	Idaho batholith and associated masses
Geologic age	Phanerozoic \| Mesozoic Cenozoic \| Cretaceous-Late Tertiary
Original map label	Ki
Comments	This unit as mapped includes a number of cross-cutting Tertiary intrusions.
Primary rock type	granitoid
Secondary rock type
Other rock types
Lithologic constituents	Major Igneous > Hypabyssal > Felsic-hypabyssal Igneous > Plutonic > GraniticAs lumped, this map unit contains a number of Cretaceous batholithic and plutonic rocks of a variety of granitic lithologies, plus a number of cross-cutting Tertiary felsic intrusions, generally hypabyssal.
Map references	Ross, P.R., Andrews, D.A., and Witkind, I.J., 1955, Geologic map of Montana: U.S. Geological Survey, 2 sheets, scale 1:500,000.
Unit references	Ruppel, E.T., O'Neill, J.M., and Lopez, D.A., 1993, Geologic map of the Dillon 1o x 2o quadrangle, Idaho and Montana: U.S. Geological Survey Miscellaneous Investigations Series Map I-1803-H, scale 1:250,000. [http://pubs.er.usgs.gov/publication/i1803H] Lewis, R.S., 1998, Preliminary geologic map of the Butte 1° x 2° quadrangle: Montana Bureau of Mines and Geology Open File Report 363, 16 p, scale 1:250,000. Berg, R.B., Lonn, J.D., 1999, The preliminary geologic map of the Nez Perce Pass 30' x 60' quadrangle, Montana, revised 1999: Montana Bureau of Mines and Geology Open File Report 339, 14 p., scale 1:100,000. Vitaliano, C.J., and Cordua, W.S., 1979, Geologic map of southern Tobacco Root Mountains, Madison County, Montana: Geological Society of America Map and Chart Series Map MC-31, scale 1:62,500. Lonn, J.D., and Berg, R.B., 1999, The preliminary geologic map of the Hamilton 30' x 60' quadrangle, Montana, revised 1999: Montana Bureau of Mines and Geology Open File Report 340, 6 p., scale 1:100,000. Berg, R.B., and Lonn, J.D., 1999, The preliminary geologic map of the Nez Perce Pass 30' x 60' quadrangle, Montana, revised 1999: Montana Bureau of Mines and Geology Open File Report 339, 14 p., scale 1:100,000.
Geographic coverage	Beaverhead - Deer Lodge - Granite - Lincoln - Mineral - Missoula - Ravalli - Sanders