Abstract

Eighteen exploratory wells drilled on the Scotian Shelf, the Grand Banks and the Labrador Shelf furnish the data for this account of the history of Canada’s Atlantic continental margin since Triassic time. A rich microfossil record supports a refined bio-stratigraphic subdivision of the Mesozoic and Cenozoic rocks, which indicates that sedimentation took place on the Atlantic continental margin at one locality or another from Triassic to Quaternary time. An appendix lists Middle Triassic to Pliocene-Pleistocene dinoflagellate-spore zones and assemblages, Pliens-bachian to Pliocene-Pleistocene foraminifer-ostracod assemblages, and Late Tithonian and Valanginian calpionellid assemblages.

The composite chronostratigraphic succession from the eighteen wells is virtually complete and over 30,000 feet thick. Hiatuses occur in many wells but none extends over the entire region. The most important is the unconformity beneath the Late Albian-Coniacian transgression across the Avalon Uplift, the hiatus at the Cretaceous-Tertiary contact encountered everywhere on the Grand Banks and the Berriasian-Valanginian hiatus of the western Scotian Shelf.

Triassic and pre-Pliensbachian rocks are non-marine to marginal marine, Pliensbachian-Tithonian and Lower Cretaceous rocks are mostly shallow marine, Upper Cretaceous rocks are mostly open marine and Cenozoic strata are deep to shallow marine. The rates of subsidence and sedimentation calculated for four wells did not exceed 10 cm/1000 y.