Abstract: Geology and Petroleum Possibilities of Grand Banks, Newfoundland

L. W. Vigrass

On the Grand Banks and adjoining offshore areas, the Scotian and East Newfoundland basins are depressed as much as 12 km below sea level and are partly filled with Mesozoic-Cenozoic sedimentary deposits. Avalon uplift, extending 402 km southeast of Newfoundland and separating the basins, was elevated periodically above sea level during the Early Cretaceous resulting in a wedge of unconformities. Grabens and half-grabens are filled with Jurassic strata on the uplift. Layered rocks include: (1) upper Paleozoic redbeds and salt deposited in rift valleys; (2) Triassic-Lower Jurassic red beds and salt deposited in a proto-oceanic gulf; (3) Jurassic strata, presumably deposited in a widening ocean, comprising pure carbonate rock at the base and seaward that grades upward and la dward into terrigenous clastic and minor carbonate rock; (4) Cretaceous sandstones at the base and landward with shaly strata at the top and offshore; the Upper Cretaceous includes pelagic chalks and was deposited in an open ocean; (5) Cenozoic terrestrial sedimentary rocks that form a prograding continental embankment.

No commercial pools have been discovered but there are significant shows in a few of the 41 wells drilled. In East Newfoundland basin, there are very good prospects of finding gas or oil in barrier-type sandstones around Jurassic and Early Cretaceous depocenters and fair prospects for gas in basal Tertiary sandstone buried 2 km or more. On northeast flank of Scotian basin there are fair prospects for hydrocarbons in restricted areas of Jurassic carbonate rocks.

AAPG Search and Discovery Article #90968©1977 AAPG-SEPM Annual Convention and Exhibition, Washington, DC