Metamorphic and structural evolution of the Straits Schist, W. Connecticut: U-PB monazite constraints

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

OSTI ID:5640320

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

U-Pb dating of monazites from two outcrops of The Straits Schist south of Waterbury Dome precisely constrains the timing of Acadian metamorphism and deformation. Synkinematic pegmatites which parallel schistosity are common in The Straits Schist south of Waterbury. A pegmatite at the type-section of The Straits Schist east of Straitsville yields U-Pb monazite ages of 385 [+-] 2.5 Ma. At both outcrops the axial planar schistosity is defined by muscovites and biotites which wrap around axes of folds but are not themselves deformed, suggesting they represent a recrystallized fabric. Monazites in the schists at both outcrops display petrographic evidence of grain boundary pinning against mica surfaces and growth across muscovite-biotite grain boundaries, consistent with growth during or after biotite and muscovite crystallization. Monazites from the schist at Straitsville and Naugatuck yield U-Pb ages of 383 [+-] 3 Ma. The U-Pb data, coupled with field and petrographic observations, suggest that pegmatite intrusion, deformation, and metamorphic recrystallization occurred within 3 Ma of about 383 Ma.

• OSTI ID: 5640320
• 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
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SCHISTS
GEOLOGIC HISTORY
LEAD ISOTOPES
METAMORPHISM
PETROGRAPHY
RECRYSTALLIZATION
URANIUM ISOTOPES
ACTINIDE ISOTOPES
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580000* - Geosciences