|Name||Devonian Tomhegan Formation Kineo Rhyolite member, garnet rhyolite|
Igneous > Volcanic > Felsic-volcanic > RhyoliteW - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite; Protolith T - Rhyolitic volcanic rocks
|Comments||Named as formation in Moose River group after Tomhegan Cove on Moosehead Lake. Type section of upper main part is on west shore of Moosehead Lake between Blue Ridge on the south and Tomhegan Cove. Type section of lower Kineo volcanic member is on northeast side of Mount Kineo in northwest 1/4 of Moosehead Lake 15-min quad. Occurs in Somerset Co. and adjacent parts of Piscataquis Co., west-central ME. Upper main part consists of blue-gray, gray-weathering sandstone that contains scattered shell lenses; dark-blue, gray-weathering slate; blue-gray, rusty, dark-gray-weathering, argillaceous sandstone, and fine- to medium-grained quartzite. Thickness estimated to be about 6,000 ft. Lower part is Kineo volcanic member which consists of massive, conchoidally fracturing felsite; massive, irregularly fracturing felsite containing abundant garnet phenocrysts; and dark tuff, light tuff, volcanic conglomerate, and flow breccia. Thickness ranges from 0 to 4,000 ft. Lower contact of main part of Tomhegan with Kineo is not well exposed; overlies Tarratine formation where Kineo is absent; upper contact not described. Report includes geologic map and correlation chart. (ME003) Unit description from USGS GEOLEX website (ME078). W - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite; GS - Greenschist facies; Protolith E - Feldspathic sandstone.|
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Boucot, A.J., 1961, Stratigraphy of the Moose River synclinorium, IN Contributions to general geology, 1959: U.S. Geological Survey Bulletin, 1111-E, p. E153-E188.
Moench, R.H., Boone, G.M., Bothner, W.A., Boudette, E.L., Hatch, N.L., Jr., Hussey, A.M., III, Marvinney, R.G. and Aleinikoff, J.N., 1995, Geologic map of the Sherbrooke-Lewiston area, Maine, New Hampshire, and Vermont, United States, and Quebec, Canada: U.S. Geological Survey Miscellaneous Investigations Series Map, I-1898-D, 56 p., 2 sheets, scale 1:250,000, Prepared in cooperation with the Maine Geological Survey and the New Hampshire Geological Survey.
US Geological Survey, 2005, National Geologic Map Database, Geologic Names Lexicon "GEOLEX", http://ngmdb.usgs.gov/Geolex/.