Spaulding Tonalite

(Spaulding Quartz Diorite of Fowler-Billings, 1949) - Weakly foliated to nonfoliated, spotted biotite quartz diorite, tonalite, granodiorite, and granite; garnet and muscovite may or may not be present.
State New Hampshire
Name Spaulding Tonalite
Geologic age Early Devonian
Lithologic constituents
Major
Igneous > Plutonic > Granitic > Tonalite
Igneous > Plutonic > Granitic > Granodiorite
Igneous > Plutonic > Dioritic > Quartz-dioriteweakly foliated to nonfoliated, spotted biotite quartz diorite
Minor
Igneous > Plutonic > Granitic > Granite
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: Kearsarge pluton = 393+/-5 Rb/Sr per NH028. Blackwater pluton = 398+/-? U/Pb, monazite per NH030. Pratt Pond pluton = 280+/-6 U/Pb, zircon, 272+/-2 U/Pb, monazite (J.N. Aleinikoff, oral commun., Dec. 1994). 365+/-? U/Pb, zircon, 365+/-? U/Pb, monazite (J.N. Aleinikoff, oral commun., May 1995). Quartz syenite dike (point within formation) = 159 K/Ar per NH037.
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, 2 sheets, scale 1:250,000.

https://ngmdb.usgs.gov/Prodesc/proddesc_37338.htm

Fowler-Billings, Katherine, 1949, Geology of the Monadnock region of New Hampshire: Geological Society of America, v. 60, p. 1249-1280.

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.

Aleinikoff, J.N., 1978, Structure, petrology, and U-Th-Pb geochronology in the Milford (15') quadrangle, New Hampshire: Hanover, N.H., Dartmouth College, Ph.D. thesis, 247 p.

NGMDB product
Counties Cheshire - Grafton - Hillsborough - Merrimack - Sullivan