Granites of southeastern Rhode Island - porphyritic granite (RIZsepg;0)

Granites of southeastern Rhode Island - porphyritic granite

Gray, pink, or greenish, generally massive, coarse-grained, porphyritic (microcline phenocrysts) granite. Contains microcline, perthite, plagioclase, quartz, and accessory biotite, hornblende, apatite, sphene, and opaque minerals; secondary chlorite, epidote, and sericite. Includes some rock mapped formerly as Bulgarmarsh Granite and Newport Granite Porphyry.

State	Rhode Island
Name	Granites of southeastern Rhode Island - porphyritic granite
Geologic age	Late Proterozoic
Lithologic constituents	Major Igneous > Plutonic > Granitic > Graniteporphyritic granite - Gray, pink, or greenish, generally massive, coarse-grained, porphyritic (microcline phenocrysts) granite. Contains microcline, perthite, plagioclase, quartz, and accessory biotite, hornblende, apatite, sphene, and opaque minerals; secondary chlorite, epidote, and sericite.
Comments	Part of Esmond-Dedham Subterrane (East Bay Area). Granites of southeastern Rhode Island - may be correlative with varieties of the Esmond Igneous Suite, from the West Bay Area. Per printed map: age of rock based on radiometric data from RI011.
References	Hermes, O.D. (comp.), Gromet, L.P. (comp.), Murray, D.P. (comp.), Hamidzada, N.A., Skehan, J.W., and Mosher, S., 1994, Bedrock geologic map of Rhode Island: Rhode Island Map Series No. 1, Kingston, Rhode Island, scale 1:100,000. Smith, B.M., 1978, The geology and Rb-Sr whole-rock age of granitic rock of Aquidneck and Conanicut Islands, Rhode Island: unpublished MS thesis, Brown University, Providence, Rhode Island, 94p.
NGMDB product	NGMDB product page for 19719
Counties	Newport

Granites of southeastern Rhode Island - porphyritic granite

Hermes, O.D. (comp.), Gromet, L.P. (comp.), Murray, D.P. (comp.), Hamidzada, N.A., Skehan, J.W., and Mosher, S., 1994, Bedrock geologic map of Rhode Island: Rhode Island Map Series No. 1, Kingston, Rhode Island, scale 1:100,000.

Smith, B.M., 1978, The geology and Rb-Sr whole-rock age of granitic rock of Aquidneck and Conanicut Islands, Rhode Island: unpublished MS thesis, Brown University, Providence, Rhode Island, 94p.