An early paleozoic plate tectonic model of Newfoundland

Abstract

We assume initial eastward subduction off the coast of the Grenvillian continent, terminated by collision of continent and subduction zone, with westward obduction of oceanic allochthons commencing in Arenig time. This regime was succeeded by oblique westward subduction beneath “proto-Newfoundland”. A projection of the Avalonian continent collided with the subduction zone in Llanvirn time, leading first to eastward obduction of oceanic material, and subsequently to rotation and deformation of the continental rise prism. Eventual continent-continent contact brought subduction to an end. Subsequent deformation, metamorphism and plutonism resulted from thermal and isostatic adjustments in the collapsed continental rise prisms. In addition to explaining many of the geological features of Newfoundland, the model predicts (1) a 30° clock-wise rotation of southeastern Newfoundland relative to northwestern Newfoundland in mid-Ordovician time, and (2) about 50 km of left-lateral displacement on the Lobster Cove Fault.