Published by the American Geophysical Union as part of the Field Trip Guidebooks Series, Volume 359.
Evolution of the Appalachian orogen spanned the Paleozoic and Mesozoic Eras. Within the confines of the northern Appalachians of the United States (the New England States—Maine, New Hampshire, Vermont, Massachusetts, Connecticut and Rhode Island—and New York), the sequence of known major Appalachian tectonic events is late Proterozoic rifting of the proto-North American craton; Ordovician subduction accompanied by destruction of the Iapetus Ocean and by obduction of tectonostratigraphic sequences; Devonian deformation, accretion, plutonism, and metamorphism, of uncertain plate tectonic context but likely related to a continent-continent collision; formation of late Carboniferous transtensive (oblique strike-slip) basins in which coal formed; and late Carboniferous to Permian thermal, plutonic, and metamorphic events. During the Mesozoic, the New England Appalachians underwent crustal extension associated with both alkalic and tholeiitic magmatism. These extensional processes reflect the opening of the North Atlantic Ocean and the creation of a passive margin, which remains today.