Carboniferous and Permian volcanic rocks

Predominantly altered andesite, basalt, and diabase with interbedded chert and argillite; includes some tuff, greenstone, and spilitic volcanic rocks; northern Cascade Mountains. Mostly schistose greenstone, some agglomerate, and rarely lapilli; includes minor beds of limestone with associated argillite and graywacke; northwestern Stevens County.
State Washington
Name Carboniferous and Permian volcanic rocks
Geologic age Devonian to Permian; Triassic in Asotin County
Comments Doyle Creek Formation, Wild Sheep Creek Formation and Coon Hollow Formation located in southeastern Asotin County; this area also includes a small outcrop of unmetamorphosed to slightly metamorphosed granodiorite, quartz diorite, and gabbro (Schuster and others, 1997) and is consolidated under "plutonic" in the lithology coding along with possible gabbro and diorite in the Chilliwack Group.
Primary rock type greenstone
Secondary rock type andesite
Other rock types chert; argillite; basalt; limestone; graywacke; keratophyre; black shale; conglomerate; plutonic rock (phaneritic)
Lithologic constituents
Major
Metamorphic > Greenstone (Zeolitic (prehnite-pumpellyite))Pillow basalt, breccia, tuff, and flow in Hozomeen Group; breccia and tuff in Chilliwack Group. Includes metabasalt in Asotin County. Partly metamorphosed to prehnite-pumpellyite facies in Hozomeen Group.
Minor
Igneous > Volcanic > Mafic-volcanic > Andesite (Volcaniclastic, volcanic breccia)Primarily outcrops in Okanogan County; some andesite in Chilliwack Formation. Also includes andesite flow and tuff in subordinate amounts.
Incidental
Sedimentary > Chemical > Chert (Bed)Possibly minor in rank; occurs primarily in Hozomeen Group.
Metamorphic > ArgillitePossibly minor in rank. May be partly metamorphosed to prehnite-pumpellite facies in Hozomeen Group but occurs associated with greenstone throughout unit.
Igneous > Volcanic > Mafic-volcanic > Basalt (Flow)
Sedimentary > Carbonate > Limestone (Bed)Possibly minor in rank (occurs in Hozomeen Group and outcrops in Asotin and Stevens Counties).
Sedimentary > Clastic > Sandstone > Graywacke (Bed)
Metamorphic > MetavolcanicIncludes keratophyre in Asotin County.
Sedimentary > Clastic > Mudstone > Shale > Black-shale (Bed)Limited to Coon Hollow Formation.
Sedimentary > Clastic > Conglomerate (Bed)Limited to Asotin County.
Igneous > PlutonicIncludes granodiorite, quartz diorite, and gabbro in Asotin County; possibly gabbro and diorite in Chilliwack Group.
Map references
Huntting, M. T., Bennett, W. A. G., Livingston, V. E. Jr., Moen, W. S., 1961, Geologic Map of Washington: Washington Division of Mines and Geology, scale 1:500,000.
Unit references
Huntting, M. T., Bennett, W. A. G., Livingston, V. E. Jr., Moen, W. S., 1961, Geologic Map of Washington: Washington Division of Mines and Geology, scale 1:500,000.
Schuster, J. E., Gulick, C.W., Reidel, S. P., Fecht, K. R., Zurenko, S., 1997, Geologic Map of Washington--Southeast Quadrant: Washington Division of Geology and Earth Resources Geologic Map GM-45, scale 1:250,000.
Reidel, S. P., Hooper, P. R., Webster, G. D., Camp, V. E., 1992, Geologic Map of Southeastern Asotin County, Washington: Washington Division of Geology and Earth Resources Geologic Map GM-40, scale 1:48,000.
Misch, P., 1977, Bedrock Geology of the North Cascades, in Brown, E. H. and Ellis, R. C. (eds.), Geological Excursions in the Pacific Northwest, Geological Society of America 1977 Annual Meeting, Seattle: Western Washington University, p. 1-62.
Joseph, N. L., 1990a, Geologic Map of the Colville 1:100,000 Quadrangle, Washington-Idaho: Washington Division of Geology and Earth Resources Open File Report 90-13, 78 p., 1 pl.
Dragovich, J. D., Logan, R. L., Schasse, H. W., Walsh, T. J., Lingley, W. S., Jr., Norman, D. K., Gerstel, W. J., Lapen, T. J., Schuster, J. E., Meyers, K. D., 2002, Geologic Map of Washington-Northwest Quadrant: Washington Division of Geology and Earth Resources Geologic Map GM-50, scale 1:250,000.
Tabor, R. W., Haugerud, R. A., Booth, D. B., Brown, E. H., 1994, Preliminary Geologic Map of the Mount Baker 30- by 60-Minute Quadrangle, Washington: U. S. Geological Survey Open File Report 94-403, 55p., 2 pls.
Counties Asotin - Okanogan - Skagit - Stevens - Whatcom