Mineral Resources On-Line Spatial Data
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|Geologic age||Middle Ordovician|
|Original map label||Opbg|
|Comments||Part of Bronson Hill Zone (Ordovician and Older Rocks) U-Pb zircon ages suggest that the Ammonoosuc Volcanics and tuffs of the Partridge Formation were erupted between 453 to 449 Ma, meaning they are of late Middle Ordovician and earliest Late Ordovician age. The stratigraphic relationships of these two units is very complex with current thought being that the Partridge lies between the lower and upper members of the Ammonoosuc Volcanics (Tucker and Robinson, 1990) per MA015.|
|Primary rock type||biotite gneiss|
|Secondary rock type|
|Other rock types|
Metamorphic > Gneissbiotite gneiss
Unpublished Digital Geologic Map of Massachusetts received from Rudi Hon at Boston College in 1998.
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.
|Geographic coverage||Hampden - Worcester|
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