Exeter Diorite

Includes associated intrusive rocks of southeastern New Hampshire; pyroxene and pyroxene-hornblende diorite and gabbro, along with minor granodiorite and granite.
State New Hampshire
Name Exeter Diorite
Geologic age Early Devonian
Lithologic constituents
Major
Igneous > Plutonic > Gabbroic > Gabbropyroxene and pyroxene-hornblende gabbro
Igneous > Plutonic > Dioritic > Dioritepyroxene and pyroxene-hornblende diorite
Minor
Igneous > Plutonic > Granitic > Granite
Igneous > Plutonic > Granitic > Granodiorite
Comments Exeter Diorite = 473+/-37 Rb/Sr per NH044. 406+/-1 U/Pb per NH045 and Bothner, oral commun., Feb. 1994.
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

Gaudette, H.E., Bothner, W.A., Laird, Jo, Olszewski, W.J., Jr., and Cheatham, M.M., 1984, Late Precambrian/early Paleozoic deformation and metamorphism in southeastern New Hampshire; confirmation of an exotic terrane [abs.]: Geological Society of America Abstracts with Programs, v. 16, p. 516.

Bothner, W.A., Gaudette, H.E., Fargo, T.G., Bowring, S.A., and Isachsen, C.E., 1993, Zircon and sphene U/Pb ages of the Exeter pluton: Constraints on the Merrimack Group and part of the Avalon composite terrane [abs.]: Geological Society of America Abstracts with Programs, v. 25, p. 485.

NGMDB product
Counties Hillsborough - Rockingham - Strafford