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Basin Histories and Hydrocarbon Source Rocks |
Department of Geology, Mount Allison University, Sackville, New Brunswick, Canada E0A 3C0
Carboniferous source rocks of relatively low to moderate maturity occur onshore along the Canadian Atlantic margin in Palaeozoic basins of western Newfoundland, New Brunswick and Nova Scotia. Coals of predominantly Westphalian age are widespread and locally abundant. In the Devono-Carboniferous Albert Formation of New Brunswick, and in equivalent Horton Group strata elsewhere in the Maritimes Basin, oil-prone type-I kerogen is predominant.
Throughout the Canadian Appalachians, the similarity of Carboniferous strata in various sedimentary basins has facilitated the recognition of four major stratigraphic cycles of deposition. Bounded in nearly every instance by unconformities, these cycles are likewise recognized offshore, where in some cases they have been the focus of commercial investigation. In the Gulf of St. Lawrence region, hydrocarbon-generating potential was early confirmed by drilling in rocks of the Windsor and Canso-Riversdale sequences. These strata may extend north from the Magdalen Basin into the Anticosti Basin, northwestward into the St. Lawrence estuary, and northeast of western Newfoundland.
Carboniferous sections south and east of Newfoundland are in most cases strongly overmature. However, recognition of equivalent Horton Group strata within the oil window in a Grand Banks well indicates the potential of Upper Palaeozoic strata to contribute to the accumulation of oil, not only within the Palaeozoic section, but also in younger strata.
