Realms of Regional Metamorphism in Southern New England, with Emphasis on the Eastern Acadian Metamorphic High

Abstract

Metamorphism in southern New England may be broadly divided into seven time-space realms as follows: 1. Grenvillian high amphib-olite to granulite facies metamorphism in North American basement of the Berkshire, Housatonic, and Manhattan regions; 2. Late Precambrian low grade and contact metamorphism in the Dedham terr-ane, with local regional development to high ampnibolite facies in the Fall River, Milford-Selden Neck, and Massabesic regions, and to granulite facies in the Pelham dome; 3. Ordovician high amphibolite to granulite facies metamorphism in the Nashoba terr-ane; 4. complex Taconian high pressure to high temperature metamorphism localized along the Berkshire-Manhattan axis, associated with eastward subduction of the edge of North America beneath island arc and eastern basement terranes; 5. a western Acadian (“Vermont”) high reaching high amphibolite facies and localized along a series of gneiss domes, separated by the Connecticut Valley metamorphic low (chlorite and biotite zones) from 6. an eastern Acadian (“New Hampshire”) high, reaching granulite facies and centered east of the gneiss domes of the Bronson Hill anticlinorium; and 7. Pennsylvanian-Permian regional metamorphism up to silliman-ite grade, best documented in southern Rhode Island, but apparently an overprint in much of central southern New England.