Mineral Resources On-Line Spatial Data
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|Name||Plainfield Formation plus Stony Creek Granite Gneiss plus Narragansett Pier Granite|
|Geologic age||Proterozoic Z? and Permian|
|Original map label||Zp+Zsc+Pn|
|Comments||Part of Eastern Uplands; Avalonian (Continental) Terrane; Avalonian Anticlinorium; Zsc only = East Haven granitic body (may be equivalent to Sterling Plutonic-Group) (includes Light House Gneiss, Branford Gneiss, and Stony Creek Granite Gneiss) (Proterozoic Z?). Printed map has individual descriptions for each unit; digital map combines all 3.|
|Primary rock type||quartzite|
|Secondary rock type||mica schist|
|Other rock types||gneiss; granitic gneiss; granite; amphibolite; calc-silicate rock; pegmatite|
Igneous > Plutonic > Granitic > GraniteStony Creek Granite Gneiss - Red to pink, unevenly medium to very coarse grained, variably foliated granite or granite gneiss, composed of oligoclase, K-feldspar, and quartz with minor biotite and magnetite, sporatic garnet (in foliated varieties), and local muscovite. Commonly contains granite and pegmatite of Narragansett Pier type (and probably age). In much of area both granites occur as innumerable veins penetrating other units or as larger bodies full of inclusions of those units, which can be mapped through the bodies of granite. Narragansett Pier Granite (Permian) - Pink to red, medium- to coarse-grained (commonly pegmatitic), generally massive (not gneissic) granite, composed of microcline, oligoclase, quartz, and biotite, and accessory muscovite and magnetite.
Metamorphic > SchistPlainfield Formation - medium- to dark-gray schist composed of quartz, oligoclase, biotite, sillimanite, and garnet.
Metamorphic > GneissPlainfield Formation - light- to medium-gray gneiss composed of quartz, oligoclase, and biotite (rarely microcline); dark-grey or green gneiss composed of plagioclase, quartz, biotite, and hornblende (commonly with diopside). Stony Creek Granite Gneiss - Red to pink, unevenly medium to very coarse grained, variably foliated granite or granite gneiss, composed of oligoclase, K-feldspar, and quartz with minor biotite and magnetite, sporatic garnet (in foliated varieties), and local muscovite.
Metamorphic > Metasedimentary > Metaclastic > QuartzitePlainfield Formation - Interlayered light-gray, thin-bedded quartzite, in places with feldspar, mica, graphite, or pyrite; and diopside-bearing quartzite.
Igneous > Plutonic > Granitic > Leucocratic-granitic > PegmatiteStony Creek Granite Gneiss - Commonly contains granite and pegmatite of Narragansett Pier type (and probably age). Narragansett Pier Granite - Considerable associated pegmatite.
Metamorphic > AmphibolitePlainfield Formation
Metamorphic > Metasedimentary > Calc-silicate-rockPlainfield Formation - calc-silicate rock
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||New Haven|
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