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Wrench Faulting as a Dominant Control in Evolution of Late Paleozoic and Early Mesozoic Basins in Maritime Provinces of Eastern Canada

Guy C. Grierson, W.E. Davitt, I. Ritchie

The Magdalen and Fundy basins occur in the Canadian Maritime Provinces, together over 77,000 mi2 in area. The Magdalen basin contains late Paleozoic sediments deposited during two major stages of tectonic evolution. In the first stage, the combination of dextral wrenching along the Lubec-Belleisle and Cobequid-Chedabucto fault zones caused extension of basement rocks and resulted in formation of a series of grabens and half-grabens. In the second stage, tectonic uplift related to the Appalachian and Variscan orogenies occurred along the south side of the Magdalen basin, with resultant deposition in foreland basin style. Wrench faulting played a major role in this uplift.

The late Paleozoic rocks deposited during these two stages are continental with alluvial fan, fluvial, and lacustrine facies. Widespread lacustrine oil shales, similar to the Green River Formation of the Uinta basin, are the source of hydrocarbons produced in the Stoney Creek field in New Brunswick. A single marine transgression occurred in Visean time and deposited carbonates and evaporites. Visean salt later formed diapirs up to 20,000 ft high.

The Fundy basin contains early Mesozoic rocks of the Newark Supergroup over 30,000 ft thick. Sinistral strike-slip along the Cobequid-Chedabucto fault zone caused a large half-graben shaped basin to form. The continental sediments infilling the basin include an interesting eolian dune facies.

An interpretation of available data suggests that significant hydrocarbon discoveries may be made both onshore and offshore in this frontier exploration area.

AAPG Search and Discovery Article #91038©1987 AAPG Annual Convention, Los Angeles, California, June 7-10, 1987.