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B.M., 1978, The geology and Rb-Sr whole-rock age of granitic rock of Aquidneck and Conanicut Islands, Rhode Island: unpublished MS thesis, Brown University, Providence, Rhode Island, 94p.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