Leucogranites and the prolonged, episodic nature of Acadian orogenesis, southwestern Connecticut

Conference · Mon Mar 01 00:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5587905

Sevigny, J H; Lanzirotti, A; Hanson, G N ^[1]

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1. State Univ. of New York, Stony Brook, NY (United States). Dept of Earth and Space Sciences

The Acadian of southwestern Connecticut exposes a middle crustal level orogenic zone comprised of multiply-deformed metapelitic and metaplutonic units that have been intruded by a number of generations of crustally-derived leucogranites. U-Pb ages from garnet + muscovite [+-] biotite leucogranites, pegmatites, and pelitic schists constrain the timing of crustal anatexis and amphibolite facies metamorphism. The Ansonia leucogranite (406 [+-] 13 Ma) is a stitching granite that shares the regional foliation with Silurian and Ordovician orthogneisses. A muscovite granite dike (390 [+-] 3 Ma) that cuts a Silurian orthogneiss has been transposed and is foliated. The Shelton muscovite granite (380 [+-] 3 Ma) is deformed by the regional foliation. Undeformed, garnet two-mica granite (376 [+-] 2 Ma) and muscovite pegmatite (375 [+-] 1 Ma) show that kinematic metamorphic recrystallization pre-dated ca. 375 Ma. Volumetrically minor biotite pegmatite is 354 [+-] 3 Ma. Morphologically distinct monazites in pelitic schists give ages ranging from ca. 395 to 376 Ma. Monazite ages in pelitic schists and crystallization ages in leucogranites and pegmatites probably record episodes of heating, fluid influx, and ductile shearing primarily between 420 and 375 Ma, but extending to 354 Ma in southwestern Connecticut.

• OSTI ID: 5587905
• Report Number(s): CONF-9303211-; CODEN: GAAPBC
• Journal Information: Geological Society of America, Abstracts with Programs; (United States), Vol. 25:2; Conference: 28. annual Geological Society of America (GSA) Northeastern Section meeting, Burlington, VT (United States), 22-24 Mar 1993; ISSN 0016-7592
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CONNECTICUT
GEOLOGIC FORMATIONS
ISOTOPE DATING
PETROGENESIS
GRANITES
APPALACHIAN MOUNTAINS
DEVONIAN PERIOD
DIKES
GEOLOGIC HISTORY
GEOTHERMOMETRY
GNEISSES
LEAD ISOTOPES
MONAZITES
OROGENESIS
SCHISTS
URANIUM ISOTOPES
ACTINIDE ISOTOPES
AGE ESTIMATION
DEVELOPED COUNTRIES
GEOLOGIC AGES
GEOLOGIC STRUCTURES
GEOLOGY
IGNEOUS ROCKS
ISOTOPES
MATERIALS
METAMORPHIC ROCKS
MINERALS
MOUNTAINS
NORTH AMERICA
PALEOZOIC ERA
PETROLOGY
PHOSPHATE MINERALS
PLUTONIC ROCKS
RADIOACTIVE MATERIALS
RADIOACTIVE MINERALS
RARE EARTH COMPOUNDS
ROCKS
THORIUM MINERALS
USA
580000* - Geosciences