Porphyritic granite

Porphyritic granite.
State New Hampshire
Name Porphyritic granite
Geologic age Jurassic
Lithologic constituents
Igneous > Plutonic > Granitic > Granite (Pluton)porphyritic granite
Comments Part of the White Mountain igneous province of McHone and Butler (1984) - Overall part of the White Mountain Plutonic-Volcanic Suite - Includes Cretaceous alkalic syenite to granitic to gabbroic plutons, minor volcanic rocks, and lamprophyre dikes of the New England-Quebec igneous province of McHone and Butler (1984); also includes Jurassic granite and syenite and less abundant quartz syenite, diorite, gabbro, nepheline syenite, and volcanic rocks of the White Mountain igneous province of McHone and Butler (1984). White Mountain Plutonic-Volcanic Suite: Red Hill Syenite = 199+/-4 K/Ar per NH031. 190+/-4 Rb/Sr, biotite per NH013. 198.5+/-1.5 K/Ar and 187.3+/-3 Rb/Sr per NH032.

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, 2 sheets, scale 1:250,000.


McHone, J.G., and Butler, J.R., 1984, Mesozoic igneous provinces of New England and the opening of the North Atlantic Ocean: Geological Society of America Bulletin, v. 95, p. 757-765.

Foland, K.A., and Faul, Henry, 1977, Ages of the White Mountain intrusives, New Hampshire, Vermont and Maine, U.S.A.: American Journal of Science, v. 277, p. 888-904.

Armstrong, R.L., and Stump, E., 1971, Additional K-Ar dates, White Mountain magma series, New England: American Journal of Science, v. 270, p. 331-333.

Henderson, C.M.B., Pendlebury, Karen, and foland, K.A., 1989, Mineralogy and petrology of the Red Hill alkaline igneous complex, New hampshire, U.S.A.: Journal of Petrology, v. 30, p. 627-666.

NGMDB product
Counties Belknap - Carroll