SILURIAN OROGENY IN THE NEWFOUNDLAND APPALACHIANS

Mapping and U-Pb age studies in the Central Mobile Belt in the southern Newfoundland Appalachians provide new insights into the tectonic evolution of this region. An older limit for the main Paleozoic deformation in the northern Hermitage Flexure is provided by the 466±3 Ma Bay du Nord Group. The regional D1 deformation of Ordovician strata is bracketed by ages of 429 +5/-3 Ma and 415±2 Ma from the synkinematic Burgeo intrusive suite. Two major metamorphic complexes yield ages of 412±2 Ma and 423 +5/-3 Ma. A 396 6/-3 Ma granite of the North Bay Granite Suite provides a younger limit for the main regional deformation and peak metamorphism. The La Poile Group, the Bear Pond rhyolite, and the Stony Lake volcanics, exposed within and north of the Hermitage Flexure, are now documented as products of extensive Silurian subaerial volcanicity and related sedimentation. Results argue for climactic Silurian orogeny in the Newfoundland Appalachians. -from Authors