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

Conference · Mon Mar 01 04:00:00 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--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 25:2
• Country of Publication: United States
• Language: English

Related Subjects

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