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Roxbury Conglomerate

Roxbury Conglomerate - Melaphyre in the Roxbury Conglomerate. Brighton Melaphyre lies within Brookline Member and consists of mafic volcanic rocks (quartz keratophyre, keratophyre, and spilite). Roxbury clearly lies nonconformably on Dedham Granite near Hull, MA; can be traced continuously over Mattapan Volcanic Complex. Age is Proterozoic Z and possibly Early Cambrian (Goldsmith, 1991).
State Massachusetts
Name Roxbury Conglomerate
Geologic age Proterozoic Z to earliest Paleozoic
Comments Part of Milford-Dedham Zone (Tertiary and Older Rocks) Secondary unit description per MA023.
Primary rock type mafic volcanic rock
Secondary rock type
Other rock types
Lithologic constituents
Major
Igneous > Volcanic > Mafic-volcanicmelaphyre; mafic volcanic rocks (quartz keratophyre, keratophyre, and spilite)
Map references
Unpublished Digital Geologic Map of Massachusetts received from Rudi Hon at Boston College in 1998.
Unit references
Zen, E-An (ed.), Goldsmith, R. (comp.), Ratcliffe, N.M. (comp.), Robinson, P. (comp.), Stanley, R.S. (comp.), Hatch, N.L., Jr., Shride, A.F., Weed, E.G.A., Wones, D.R., 1983, Bedrock Geologic Map of Massachusetts: U.S. Geological Survey, Reston, VA, scale 1: 250,000.
Goldsmith, Richard, 1991, Stratigraphy of the Milford-Dedham zone, eastern Massachusetts; an Avalonian terrane, Chapter E, IN Hatch, N.L., Jr., ed., The bedrock geology of Massachusetts: U.S. Geological Survey Professional Paper, 1366-E-J, p. E1-E62.
Counties Middlesex - Norfolk - Plymouth - Suffolk