Characteristics and Evolution of the Central Mobile Belt, Canadian Appalachians

Abstract

The Early to Middle Paleozoic stratigraphic, structural, and metamorphic histories of central Newfoundland and New Brunswick show remarkable similarities. These characteristics should be reflected in zonal or terrane subdivisions of the Canadian Appalachians, and we therefore recombine the Dunnage and Gander zones/terranes into the Central Mobile Belt (CMB). In our interpretation, the CMB is a deformed Ordovi-cian ocean basin (Iapetus II), that was formed in between the Taconic magmatic arc and the Avalon continent during Mariana-type subduction of the Iapetus I ocean. The generalized stratigraphic sequence of the CMB records the formation of ophiolitic crust and continental margin sediments of Iapetus II in Early Ordovician times, which was followed by a period of relative quiescence when spreading stopped (limestone and shale deposition). Late Ordovician to Silurian closure of Iapetus II was accompanied by the deposition of a thick clastic sequence and locally volcanics. A complex history of thrusting, ...