Silurian U Pb zircon intrusive ages for the Red River anorthosite (northern Cape Breton Island): Implications for the Laurentia-Avalonia boundary in Atlantic Canada

Current interpretations of the geology of Cape Breton Island suggest that it exposes a complete cross-section of the Appalachians from Laurentia across Iapetan vestiges to Avalonia. Crucial to this view is the presence of ca. 1 Ga plutons, including anorthosites, which have been regarded as correlatives of Grenvillian basement, a correlation that overlooks the fact that Avalonia is also underlain by a ca. 1 Ga basement. We analyzed zircons from...