Concord Granite (NHDc1m;0)

State	New Hampshire
Name	Concord Granite
Geologic age	Late Devonian
Original map label	Dc1m
Comments	Part of the New Hampshire Plutonic Suite (Late to Early Devonian) - Includes synkinematic and postkinematic granitoids related to the Acadian orogeny. Ages range from 410 to 365 Ma. New Hampshire Plutonic Suite: Newfound Lake pluton = 373 (concordant) U/Pb, monazite (J.N. Aleinikoff, oral commun., Feb. 15, 1984). Sunapee pluton = 349+/-? Rb/Sr per NH034. 366+/-8 Rb/Sr; recalculation by J.N. Aleinikoff (oral commun., July 20, 1990) of combined Rb/Sr data of NH028 and NH034. 364+/-2 U/Pb per NH014 and J.N. Aleinikoff, oral commun., July 20, 1990. Concord Granite = 365+/-20 U/Pb per J.N. Aleinikoff, oral commun., Mar. 5, 1986. 375+/-? U/Pb, monazite from pegmatite in Concord Granite per NH030. New Durham pluton = 377+/-? U/Pb, monazite per NH030. Hooksett pluton = 402+/-? Rb/Sr per NH034 and 365+/-20 U/Pb per J.N. Aleinikoff, oral commun., Mar. 5, 1986. Barrington pluton = 363+/-? U/Pb, monazite per NH030. Fitzwilliam Granite = 383+/-? Rb/Sr per NH034 and NH035.
Primary rock type	granite
Secondary rock type	tonalite
Other rock types
Lithologic constituents	Major Igneous > Plutonic > Granitic > Granite (Pluton)gray two-mica granite Minor Igneous > Plutonic > Granitic > Tonalite (Pluton)locally grading to tonalite
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. [http://pubs.er.usgs.gov/publication/ds215]
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. Harrison, T.M., Aleinikoff, J.N., and Compston, William, 1987, Observations and controls on the occurence of inherited zircon in Concord-type granitoids, New Hampshire: Geochimica et Cosmochimica Acta, v. 51, p. 2549-2558. Lyons, J.B., and Livingston, D.E., 1977, Rb-Sr age of the New Hampshire Plutonic Series: Geological Society of America Bulletin, v. 88, p. 1808-1812. Eusden, J.D., Jr., and Barreiro, Barbara, 1988, The timing of peak high-grade metamorphism in central-eastern New England: Maritime Sediments and Atlantic Geology, v. 24, p. 241-255. Hayward, J.A., 1983, Rb-Sr geochronology and the evolution of some peraluminous (two mica) granites of New Hampshire [abs.]: Geological Society of America Abstracts with Programs, v. 15, p. 146. Hayward, J.A., 1987, Rb-Sr and oxygen isotope analyses of three two-mica granite plutons in Maine, New Hampshire and Massachusetts [abs.]: Geological Society of America Abstracts with Programs, v. 19, p. 18.
Geographic coverage	Belknap - Carroll - Cheshire - Grafton - Hillsborough - Merrimack - Rockingham - Strafford - Sullivan