Mineral Resources On-Line Spatial Data
Mineral Resources > Online Spatial Data > Geology > by state > Connecticut
|Name||Ordovician? granitic gneiss|
|Geologic age||Middle Ordovician?|
|Original map label||Og|
|Comments||Part of Central Lowlands; Iapetus (Oceanic) Terrane - Connecticut Valley Synclinorium Ansonia Gneiss is here referred to as Ansonia leucogranite. On the basis of field and laboratory studies, Ansonia, Beardsley, Pumpkin Ground, and Shelton gneisses, previously considered stratigraphic units, are reinterpreted as plutonic. Ansonia is described as a strongly lineated and moderately foliated, fine-grained, garnet-bearing, biotite-muscovite leucogranite with a well-developed granoblastic texture. Intrudes Beardsley and Pumpkin Ground orthogneisses. Maximum age from zircons is 417+/-1.5 Ma. Conservative interpretation of isotopic data is crystallization between 393 and 419 Ma and therefore, authors assign an age of 406+/-13 Ma (Late Silurian to Early Devonian) to the Ansonia (Sevigny and Hanson, 1993) per CT007.|
|Primary rock type||granitic gneiss|
|Secondary rock type||schist|
|Other rock types|
Metamorphic > GneissWhite, light-gray, buff, or pink, generally foliated granitic gneiss, composed of sodic plagioclase, quartz, microcline, muscovite, and biotite, and locally garnet or sillimanite.
Metamorphic > Schist > Mica-schistCommonly contains numerous inclusions or layers of mica schist.
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||Fairfield - Hartford - Litchfield - New Haven|
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