Late Quaternary plume, nepheloid and turbidite sedimentation and effect of the Gulf Stream near the tail of the Grand Banks, Newfoundland

Abstract

Cores collected from the tops of the Fogo Seamounts southwest of the Grand Banks of Newfoundland contain considerable amounts of detrital clay. The seamounts rise at least 1 km above the surrounding sea floor and are an unlikely place for sedimentation by turbidity currents. Sedimentological and micropaleontological evidence suggests that large amounts of detrital clay were injected into the system during glacial and interglacial stages by turbidity currents and surface sediment plumes. The main source of sediment was the Laurentian Channel, although some sediment was injected through the canyons around the Grand Banks. Surface sediment plumes were strongly influenced by the Labrador Current and by the surface circulation of the Gulf Stream. Fine-grained sediments injected into the system by turbidity currents through the Laurentian Channel were probably trapped by the deep circulation of the Gulf Stream and dispersed to the northeast. Effects of the sediment drift induced by the deep Gulf Stream circulation is also reflected in an abrupt eastward bent of the depositional lobes of the Laurentian Fan and in the shape of the Newfoundland Ridge.