Blackstone Group and its four members, Sneech Pond Schist, Quinnville Quartzite, Mussey Brook Schist, and Hunting Hill Greenstone, are extended into eastern MA. A definite Proterozoic Z age is assigned because units are intruded by Proterozoic Z plutonic rocks and are more metamorphosed than nearby Cambrian Hoppin Formation.
Source: GNU records (USGS DDS-6; Reston GNULEX).
Used as Quinnville Quartzite of Blackstone Group of Proterozoic Z age.
Source: GNU records (USGS DDS-6; Reston GNULEX).
Quinnville Quartzite of Blackstone Group not shown separately outside of type area. Much of Blackstone Group shown as undivided. Recent mapping by Drier and Mosher (1981, NEIGC Guidebook) indicated no basis for distinguishing Mussey Brook Schist from Sneech Pond Schist, both of which are members of the Blackstone Group. On State bedrock map of Zen and others (1983), both units are lumped into one unnamed mica schist and phyllite unit within Blackstone Group. It is possible that Quinnville Formation is only a lens in the sequence, or that the schist was repeated by folding. Report includes geologic maps and correlation charts. [Chapters A-J in U.S. Geological Survey Professional Paper 1366 are intended as explanations and (or) revisions to 1:250,000-scale MA State bedrock geologic map of Zen and others (1983).]
Source: GNU records (USGS DDS-6; Reston GNULEX).
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
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