Esmond Igneous Suite - mafic/intermediate rock (RIZem;0)

Esmond Igneous Suite - mafic/intermediate rock - Dark-gray, purple, or black, medium- to coarse-grained rock that may contain plagioclase, quartz, clinopyroxene, hornblende, olivine, and accessory biotite, epidote, sphene, zircon, apatite, and opaque minerals; secondary chlorite, sericite, and saussurite. Massive to variably foliated. Composition includes tonalite, quartz diorite, diorite, and gabbro. Includes rock mapped formerly as quartz diorite.

State	Rhode Island
Name	Esmond Igneous Suite - mafic/intermediate rock
Geologic age	Late Proterozoic
Original map label	Zem
Comments	Part of Esmond-Dedham Subterrane (West Bay Area) Per printed map: age of rock based on radiometric data from RI005 (U-Th-Pb (zircon) dating by Hermes and Zartman (1985) who record a 621+/-8 Ma emplacement date) and RI009.
Primary rock type	tonalite
Secondary rock type	quartz diorite
Other rock types	diorite; gabbro
Lithologic constituents
Map references	Hermes, O.D., Gromet, L.P., Murray, D.P., Hamidzada, N.A., 1994, Geologic Map of Rhode Island, file name = bedrock_shp.zip (870kb) obtained from Rhode Island Geographic Information System, http://www.edc.uri.edu/rigis-spf/Statewide/state.html#geology , shapefile or interchange file, scale 1/100,000. [http://www.edc.uri.edu/rigis-spf/Statewide/state.html#geology]
Unit 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. Hermes, O.D., and Zartman, R.E., 1985, Late Precambrian and Devonian plutonic terrane within the Avalon Zone of Rhode Island: Geological Society of America Bulletin, v. 96, p. 272-282. Hermes, O.D., Gromet, L.P., and Zartman, R.E., 1981, Zircon geochronology and petrology of plutonic rocks in Rhode Island, p. 315-338: in Boothroyd, J.C., and Hermes, O.D., editors, Guidebook to Field Studies in Rhode Island and Adjacent Areas: 73rd New England Intercollegiate Geological Conference, University of Rhode Island, Kingston, 383p.
Geographic coverage	Providence