Mesozoic and Cenozoic History of the Grand Banks of Newfoundland

Abstract

Two wells drilled by Pan American in the Grand Banks of Newfoundland gave the first stratigraphic section of Cretaceous and Cenozoic age northeast of Long Island and the only Jurassic and possible Permian sections in the Atlantic Continental Margin of North America.Integrated analysis of lithic and faunal data showed a minimum of seven sequences present. These are Pleistocene, Middle and Upper Miocene, Intra-Eocene, Paleocene and lowest Eocene, Upper Cretaceous, Middle Cretaceous, and Neocomian in age.The rocks range from halite and anhydrite, of possible Permian depositional age, to limestones, in the Upper Jurassic, lower Upper Cretaceous, mid-Eocene and mid-Miocene, and sandstones, which dominate the Neocomian, Upper Eocene, and Middle Miocene. Variable proportions of shale and silty mudstone occur throughout.The microfaunas contain both Tethyan and Boreal elements, and suggest oceanic circulation changes, sea-floor spreading, or both.Depositional environments ranged from subaerial, for the quartz arenites, through very low-land, for stream and swamp deposits, to estuarine, lagoonal, bank and open-shelf warm-marine environments, in which were deposited fine sand to clay-size terrigenous sediment, or, in its absence, skeletal carbonates or lime muds. The first dominant cooling trend appeared in the Late Miocene.All erosional environments of the hiatal episodes appear to have been subaerial and humid.A salt dome intruded the Tors Cove well section, its last movement being in mid-Early Eocene.Periodic interregional tectonic oscillations produced the erosional and depositional episodes of the major baselevel transit cycles. Their total effect is a sedimentary wedge, thickening by preservation toward the continent's edge, and representing one-half or less of Upper Mesozoic and Cenozoic time.