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Empire shale

Empire shale: green dense, laminated shale with some red beds. Distinguished only in general vicinity of Helena.
StateMontana
NameEmpire shale
Geologic ageProterozoic | Mesoproterozoic
Original map labelpCe
CommentsModern mapping also correlates this unit northward from Helena to Glacier National Park.
Primary rock typemeta-argillite
Secondary rock typequartzite
Other rock typescarbonate
Lithologic constituents
Major
Metamorphic > Metasedimentary > Metaclastic > Argillite (Greenschist)
Minor
Metamorphic > Metasedimentary > Metaclastic > Quartzite (Greenschist)
Incidental
Sedimentary > Carbonate (Calcareous)Weakly metamorphosed limestones.
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.
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.
Obradovich, J.D. and Cobban, W.A., 1975, A time-scale for the Late Cretaceous of the Western Interior of North America, in Caldwell, W.G., ed., The Cretaceous System in the Western Interior of North America: Geological Association of Canada S
Harrison, J.E., Whipple, J.W., and Lidke, D.J., 1998, Geologic map of the western part of the Cut Bank 1° x 2° quadrangle, northwestern Montana: U.S. Geological Survey Miscellaneous Geologic Investigations Series Map I-2593, scale 1:250,000.
Harrison, J.E., 1972, Precambrian Belt basin of northwestern United States--Its geometry, sedimentation and copper occurrences: Geological Society of America Bulletin, v. 83, no. 5, p. 1215-1240.
Whipple, J.W., 1992, Geologic map of Glacier Park, Montana: U.S. Geological Survey Miscellaneous Investigations Series Map I-1508-F, 1 sheet, scale 1:100,000.
Whipple, J.W., Connor, J.J., Raup, O.B., and McGimsey, R.G., 1984, Preliminary report on the stratigraphy of the Belt Supergroup, Glacier National Park and adjacent Whitefish Range, Montana, in McBane, J.D., and Garrison, P.B., eds., Northwest Montana an
Earhart, R.L., Mudge, M.R., and Connor, J.J., 1984, Belt Supergroup lithofacies in the Northern Disturbed Belt, northwest Montana, in McBane, J.D., and Garrison, P.B., eds., Northwest Montana and adjacent Canada--Montana Geological Society 1984 Field Con
Geographic coverageBroadwater - Cascade - Jefferson - Lewis and Clark - Meagher

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