Tectonic significance of Silurian magmatism in the Canadian Appalachians

New U-Pb ages for granites from the New Brunswick part of the Canadian Appalachians indicate that >90% of the undeformed felsic plutons are Silurian and not Devonian as previously thought. Silurian igneous and sedimentary assemblages were recently recognized throughout the Canadian Appalachians, although the petrogenetic types of magmas as well as the grades of metamorphism and deformation vary widely. Our data support proposed tectonic models that suggest relatively continuous subduction and orogenic activity in the Canadian Appalachians from Middle Ordovician to Middle Devonian time.