Abstract

Georges Bank Basin is a box-shaped trough built on a blockfaulted basement of igneous, metamorphic, and sedimentary rocks. The deepest part of the basin (>16 km) and the oldest (?) sedimentary rocks are restricted to south-central Georges Bank. Toward the northeast and southwest, the sedimentary section thins to >2 km over the La Have Platform and the Long Island Platform. The only deep wells in the area are the COST Nos. G-1 and G-2; data from these wells will not be released until 60 days after acceptance of tract bids from the first oil and gas lease sale. Seismic correlation with the Shell Mohawk B-93 well on the Scotian Shelf indicates that most of the sedimentary rocks in the Georges Bank Basin are Jurassic and older. Potential reservoir rocks are considered to be Jurassic sandstone and limestone units. Structural highs with associated draping of Jurassic and basal Lower Cretaceous strata over basement blocks are considered potential hydrocarbon traps.

Baltimore Canyon trough is an elongate northeast trending basin that contains 18 km of Jurassic and younger marine and nonmarine sedimentary rocks. Lithologic and stratigraphic data from the COST Nos. B-2 and B-3 wells indicate that Lower Cretaceous and Jurassic rocks on the shelf are nonmarine to shallow marine sandstone, shale, and limestone. The dominance of terrestrial over marine-derived organic matter in rock samples suggests that gas rather than oil will predominate. As of March 1980,19 wildcat wells had been completed and three had yielded significant recoveries of natural gas. The largest discovery reported is probably associated with a large rollover trap on the downthrown block of a Cretaceous and Jurassic growth fault. Potential hydrocarbon traps in carbonate rocks beneath the Continental Slope have not yet been explored.