The Dunbar dome in NE Wisconsin is a critical structural feature in the early Proterozoic Penokean orogen. We interpret the dome as being a large-scale, fold-interference structure resulting from polydeformation modified by diapirism. The Wisconsin magmatic terrane, as represented by the rocks in the Dunbar dome, differs from the epicratonic, early Proterozoic sedimentary-volcanic sequence (Marquette Range Supergroup) in Michigan to the N, in stratigraphy, structure and volume and composition of igneous rocks. We interpret the Wisconsin magmatic terrane as an oceanic-arc complex that was sutured to the N American continent during development of the Penokean orogen. Similar interpretations based on broad regional observations have been proposed previously.-from Authors
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The Dunbar gneiss- granitoid dome: implications for early Proterozoic tectonic evolution of northern Wisconsin ( USA).