Abstract: Geology of Labrador Sea and its Petroleum Potential

N. J. McMillan

Labrador Sea is a fossil ocean, still deep, containing a "fossil" midridge almost completely buried by Cenozoic sedimentary rocks.

The shelves adjacent to Labrador, Baffin Island, and Greenland are smooth and range from 100 to 500 m deep. In most places the Labrador and Greenland shelves are separated from the mainland by a marginal channel extending down to a depth of 600 m. Although there are isolated deeps between the Baffin Island shelf and the mainland, it is not clear whether or not a true tectonically controlled marginal channel is present.

Basin depocenters were present by Middle Jurassic time but most of the sedimentary rocks are Cretaceous and Cenozoic clastic deposits. Most prospects for petroleum are related to horsts on the Greenland and Labrador offshore. Sands around some of these horsts have favorable reservoir characteristics. Middle Cenozoic sedimentary rocks mostly are not influenced by the earlier block faulting except on the Baffin Island shelf. Off southern Baffin Island the Ungava transform fault zone was active much later, and structures there contain draping of presumed post-Eocene sedimentary deposits.

Acoustic basement is prospective especially on the seaward extension of the Appalachians. Off Baffin Island salt diapirs are present.

The quality and quantity of the organic matter present in the Mesozoic-Cenozoic sedimentary rocks of the shelves of the Labrador Sea encourage petroleum exploration. Under the shelf the favorable maturation levels are improved by "hot-spot" areas related to rifting.

Six wildcat wells have been drilled to basement on separate structures in the Labrador Sea. Three resulted in hydrocarbon discoveries.

AAPG Search and Discovery Article #90973©1976-1977 AAPG Distinguished Lectures