Metamorphism and Plutonism

There are three types of thermal effects which took place during the Acadian orogeny: volcanism, metamorphism, and plutonism (Tucker, et al).

The Acadian orogenesis in the Northern Appalachians was accompanied by metamorphism and the intrusion of syntectonic to posttectonic granites that range in age from Silurian to Carboniferous. Syntectonic intrusions are associated with compressive mechanism and migmatization, while posttectonic intrusions are caused by the relaxation of compressive forces and gravity-induced rise (Rast and Skehan, 1993). However, the style of metamorphism within the Northern Appalachians differs depending on the age and the specific region of deformation. Posttectonic metamorphism and plutonism are characteristic of the Acadian orogen in many areas of Maine. The Appalachians in New Hampshire, Massachusetts, and Connecticut (the Presidential Range), however, are dominated by syntectonic metamorphism and plutonism (J.D. Eusden Jr. Et Al, 2000). Furthermore, much of Maine and New Brunswick is characterized by Silurian deformed strata with intruded granitoids of medium to low metamorphic grade (Rast and Skehan, 1993). However, in the Appalachians of New England, Devonian age metamorphism is much more common and often high-grade.

 

*Bold face words are defined in the glossary.

 

Acadian metamorphism in Newfoundland

 

Extent of Acadian metamorphism, plutonism, an deformation in Newfoundland.