The Structural Evolution of Western Newfoundland and Its Implications on Petroleum Prospects

Ian M. Atkinson
Memorial University of Newfoundland, St. John's, NF

Western Newfoundland's structural complexity is the result of three major orogenies – the Taconic, Salinic and Acadian. A thick carbonate sequence was deposited in the late Cambrian to early Ordovician. This carbonate platform, part of the margin of the Laurentia supercontinent that extended from Texas to Labrador, has been a major petroleum producer.

The Taconic orogeny emplaced the slope sediments on the outboard platform margin resulting in the development of a foreland basin setting to the west of the approaching allochthon. Rich source rock sediments were carried into the foreland basin at this time. The outboard loading induced a peripheral bulge to migrate across the platform developing horst and tilted fault block structures. The foreland basin was subsequently covered by the Lourdes Limestone, a regionally extensive seismic marker in offshore Western Newfoundland. The Salinic orogeny saw the continued movement of the allochthon from the east, but seismic evidence shows it had minimal affects within the foreland basin.

During the Acadian orogeny, major structural deformation occurred in Western Newfoundland. Strike-slip motion between the Laurentian and Gondwana plates created the Carboniferous basins of Western Newfoundland and inverted the faults within the carbonate platform. This fault inversion was primarily responsible for the creation of a triangle zone in the near shore area. The identification of this triangle zone stimulated petroleum exploration activity in the 1990's. However, no exploration drilling took place in the foreland basin, to the west of the triangle zone. This area is the focus of new exploration interest today.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005