The influence of shelf-crossing glaciation on continental slope sedimentation, Flemish Pass, eastern Canadian continental margin

Flemish Pass is a small, perched slope basin seaward of the Grand Banks on the eastern Canadian continental margin. Glacial ice crossed the Grand Banks to reach the upper continental slope during some Mid to Late Quaternary glaciations but terminated on the middle shelf, 200 km distant, at the last glacial maximum. This study investigates the effect of ice extent on slope sedimentation processes. Sediment in Flemish Pass comprises muds of hemipelagic and proglacial plume origin, minor thin-bedded turbidite sands, and thick-bedded mass-transport deposits (MTDs). A regional stratigraphy, based on 500 km of high-resolution seismic profiles and 60 piston cores up to 11 m long, was dated using 30 radiocarbon dates, the presence of Ash Zone II and oxygen isotope stratigraphy. This provided stratigraphic control for till tongues in water depths < 600 m along the Grand Banks margin, recognized from oxygen isotope stage (OIS) 6 and locally from OIS 4. Five types of MTD deposited during OIS 4 and 6, were recognized from seismic-reflection data and related to ice sheet processes in the area. During OIS 2, when ice sheets did not reach the area, no MTDs are found in the basin, and the sedimentation rates decreased to ~ 2 mm/yr. The variation of sediment supply over the last 170 ka indicates a strong tie between the styles and rate of sedimentation in the basin and the presence of shelf-crossing ice.