The Ordovician System of Canada: an extensive stratigraphic record of Laurentian shallow water platforms and deep marine basins

Abstract

Ordovician rocks extensively border and cover Laurentia or the North American Craton in Canada. These rocks represent diverse and significant successions spread across a variety of depositional and palaeogeographic settings in the Canadian Arctic Islands, Eastern Canada, Western Canada and the Canadian Interior. During much of the Ordovician, Laurentia straddled the palaeoequator and was flooded by extensive epicontinental seas, experiencing high temperatures and high faunal diversity. The central and western parts of the Laurentian Craton remained relatively stable during the Ordovician, but there was substantial tectonic activity with the Taconic Orogeny affecting the Appalachian area and the Pearya composite terrane affecting the Franklinian Margin along its eastern and northern margins, respectively. The large Hudson Bay and Williston basins and smaller satellite basins cover the cratonic interior in Canada. These shallow intracratonic basins, dominated by marine carbonates with some evaporites, are the erosional remnant of a more extensive sea episodically connected with the adjacent platformal areas during the Ordovician. The Global Boundary Stratotype Section and Point (GSSP) for the base of the Ordovician System is exposed in Green Point, western Newfoundland while the Ordovician–Silurian boundary interval is well exposed on Anticosti Island, Québec but is also present in Ontario, Manitoba, Yukon and Arctic Canada.