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Ammonoosuc Volcanics, Bimodal volcanic rocks

Ammonoosuc Volcanics, Bimodal volcanic rocks - Locally includes unmapped Oals.
State New Hampshire
Name Ammonoosuc Volcanics, Bimodal volcanic rocks
Geologic age Middle - Upper Ordovician
Comments Part of the Central Maine Composite Terrane (Central Maine Trough) - Variably metamorphosed sedimentary and volcanic rocks of greenschist to granulite facies, locally migmatized. Area includes structural belts between the Monroe fault on the west and the Campbell Hill fault on the east; that is, the Bronson Hill anticlinorium, Piedmont allochthon, Kearsarge-central Maine synclinorium, central New Hampshire anticlinorium, and Rochester-Lebanon (Maine) antiformal synclinorium. Ammonoosuc Volcanics = 461+/-8 U/Pb per J.N. Aleinikoff, oral commun., Feb. 1994.
Primary rock type bimodal suite
Secondary rock type
Other rock types
Lithologic constituents
Igneous > Volcanic > Felsic-volcanicbimodal volcanic rocks
Igneous > Volcanic > Mafic-volcanicbimodal volcanic rocks
Map references
Bennett, D. S, , Wittkop, C.A., and Dicken, C.L., 2006 , Bedrock Geologic Map of New Hampshire - A Digital Representation of the Lyons and others 1997 map and ancillary files: U.S. Geological Survey Data Series 215, scale 1:250,000, CD-ROM.
Unit references
Lyons, J.B., Bothner, W.A., Moench, R.H., and Thompson, J.B., Jr., 1997, Bedrock Geologic Map of New Hampshire: Reston, VA, U.S. Geological Survey Special Map, 1:250,000, 2 sheets.
Counties Cheshire - Coos - Grafton - Sullivan