Role of Proterozoic and Paleozoic Volcanic Rocks in the Geologic Evolution of the Southeastern New England Avalon Zone

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Within the Appalachian orogenic belt, southeastern New England plays a key role in models for Appalachian orogenesis, because it contains one of the last accreted terranes and appears to have the most complete record of the Alleghanian Orogeny. Part of this history involves igneous activity, including late Proterozoic arc accretion, followed by episodic extensional quartz-rich alkalic magmatism throughout much of the Paleozoic succeeded finally by a brief period of peraluminous granite emplacement in the Permian. This study involves extensive zircon geochronology on two suites of volcanic rocks from the Avalon terrane. The study of these rocks may clarify crustal, tectonic and magmatic processes that occurred during the pre-collisional and early accretion stages of the Alleghanian orogenic episode of New England.