Mineral Resources On-Line Spatial Data
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|Name||Stamford Granite Gneiss|
|Geologic age||Proterozoic Y|
|Original map label||Ysg|
|Comments||Part of Taconic-Berkshire Zone (Ordovician and Older Rocks) A dike-like feature of Stamford Granite, found near eastern margin of Green Mountain massif near locality 1 on this map (represented by sample 172), was incorrectly referred to as a probable Late Proterozoic diabase dike by Ratcliffe on his section of the Bedrock Map of Massachusetts (Zen and others, 1983). U-Pb zircon dates from Karabinos and Aleinikoff (1988, 1990) yield an age of 959+/-4 Ma. Unpublished data from Harding and Mukasa yield a U-Pb zircon date of about 950 Ma per MA011.|
|Primary rock type||granitic gneiss|
|Secondary rock type|
|Other rock types|
Metamorphic > GneissWhite to gray biotite-oligoclase-microcline Rapakivi granite gneiss containing blue quartz.
Unpublished Digital Geologic Map of Massachusetts received from Rudi Hon at Boston College in 1998.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.
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