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B.M., 1978, The geology and Rb-Sr whole-rock age of granitic rock of Aquidneck and Conanicut Islands, Rhode Island: unpublished MS thesis, Brown University, Providence, Rhode Island, 94p.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