Palaeogeography of Atlantic Canadian Continental Shelves from the Last Glacial Maximum to the Present, with an Emphasis on Flemish Cap

Abstract

Flemish Cap is a fragment of continental crust detached from related terranes in Europe and Ireland by crustal spreading and stretching over the last 150 Ma. It has a core of basement rocks (chiefly Hadrynian granite) surrounded by younger sedimentary rocks. Since the last glacial maximum the geography of the surrounding shelves has changed due to glacial eustatic and isostatic processes. Glacier ice reached the edge of the continental shelves in most areas at its maximum extent. The ice retreated by calving in deeper water, with accelerated calving of the Gulf of St. Lawrence beginning just before 14 ka BP (radiocarbon years). By 13 ka BP ice was largely confined to land areas. An archipelago on the outer shelf, from Grand Bank to the continent, persisted from >13 ka BP until c. 8 ka BP. Flemish Cap was probably not glaciated, although it was – and continues to be – impacted by icebergs. It was probably not emergent, although it was impacted by high wave energy during sealevel lowering. In comparison with the more 'hostile' glacial and ice-proximal environments along the shelf edge from southern Labrador to New England Flemish Cap was a relatively benign shallow-water environment with hard substrates, and may be a suitable candidate for a glacial marine refugium.