State | Rhode Island |
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Name | Scituate Igneous Suite - rhyolite |
Geologic age | Devonian |
Lithologic constituents | Major
Igneous > Volcanic > Felsic-volcanic > Rhyolite (Flow, Dike or sill)rhyolite - Pink to gray, fine-grained, locally porphyritic felsite (phenocrysts of quartz and Carlsbad-twinned orthoclase). Includes some hypabyssal intrusive rocks (feeder dikes and sills), and some probable lava flows. Contains accessory biotite, opaque minerals, zircon, monzonite, fluorite, sphene, apatite, and epidote. Quartz phenocrysts commonly are embayed and partly resorbed; matrix is fine-grained intergrowth of quartz and feldspar, probably formed from devitrified glass.
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Comments | Part of Esmond-Dedham Subterrane (West Bay Area) |
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. |
NGMDB product | |
Counties | Kent - Washington |