Stratigraphic Reference Section for Georges Bank Basin--Depositional Model for New England Passive Margin

Abstract

A multichannel seismic reflection profile (U.S. Geological Survey line 19), calibrated with the COST G-1, COST G-2, and Shell Mohican I-100 wells, and seismic-sequence analysis shows that the chronostratigraphic and lithostratigraphic units and depositional history of the Georges Bank basin are similar to those of the Scotian basin. Carbonate rocks of the Iroquois and Abenaki Formations, as much as 16,000 ft (4,800 m) thick, dominated the eastern half of the Georges Bank basin during the Jurassic. As much as 7,500 ft (2,300 m) of the coeval terrigenous clastic deposits of the Mohican, Mohawk, and Mic Mac Formations accumulated updip (westward) in sublittoral, paralic, and nonmarine environments. Siliciclastic deposition, as much as 6,000 ft (1,800 m), dominated the entire basin throughout the Cretaceous and Cenozoic, and it was punctuated briefly by carbonate deposition during the Hauterivian and Paleogene. Tentative correlation between the Georges Bank basin sequences and those of the adjacent, deep North American basin suggests that the deep-sea facies were strongly influenced by depositional events on the shelf. Deposition in both areas has been sensitive to changes in sea level and to paleoclimatic cycles.