Mineral Resources On-Line Spatial Data
Mineral Resources > Online Spatial Data > Geology > by state > Connecticut
|Geologic age||Middle or Lower Ordovician?|
|Original map label||Omo|
|Comments||Part of Eastern Uplands; Iapetus (Oceanic) Terrane - Bronson Hill Anticlinorium. Swanzey, Pauchaug, Monson, and Fourmile Gneisses represent metamorphosed intrusive igneous rocks and yield ages from 454 to 442+3/-2 Ma. Therefore, ages range from early Late through latest Ordovician. Authors suggest that they represent the plutonic root of a calc-alkaline magmatic arc at least 250 km long that was produced partly or entirely on a continental margin in the Late Ordovician. The overlying Ammonoosuc Volcanics and Partridge Formation, rather that resting unconformably on these plagioclase-rich plutonic gneiss, are now known to have had a magmatic history overlapping with them and are approximately the same age (Tucker and Robinson, 1990) per CT012.|
|Primary rock type||gneiss|
|Secondary rock type||amphibolite|
|Other rock types|
Metamorphic > GneissInterlayered light to dark, mostly medium to coarse-grained gneiss and amphibolite; gneiss composed of plagioclase, quartz, and biotite, with hornblende in some layers and microcline in others; traces of garnet, epidote, and magnetite.
Metamorphic > Amphibolite
Connecticut Geological and Natural History Survey, DEP, in cooperation with the U.S. Geological Survey, 2000, Bedrock Geology of Connecticut, data format: shapefile, file name: bedrock, downloaded from: http://magic.lib.uconn.edu/cgi-bin/MAGIC_DBsearch2.pl?Geography=37800&Loc=0000 on 9/18/2003, scale 1:50,000.
Rodgers, John, compiler, 1985, Bedrock Geological Map of Connecticut: Connecticut Geological and Natural History Survey, Hartford, Connecticut, 2 sheets, scale 125,000.
|Geographic coverage||Hartford - Middlesex - New Haven - Tolland|
Show this information as [XML]