The Laurentian Channel: a major cross-shelf trough in Atlantic Canada

Abstract

The Laurentian Channel is a wide, deep, U-shaped, glacially-excavated, cross-shelf trough in Atlantic Canada. It extends NW–SE approximately 700 km from the mouth of the St Lawrence River, across the Gulf of St Lawrence and terminates at the edge of the continental shelf south of Newfoundland (Fig. 1a, e). The Laurentian Channel was a major conduit of ice-stream flow on the SE margin during several advances of the Laurentide Ice Sheet. Fig. 1. Bathymetry and geophysical profiles of the Laurentian Channel, Atlantic Canada. ( a ) Multibeam image showing the extent of the Laurentian Channel. Image developed from digital elevation model of Shaw & Courtney (2004). Grid-cell size 789 m. BB, Burgeo Bank; HC, Hermitage Channel. ( b ) Seismic-reflection profile along the axis of the SE portion of the Laurentian Channel. Tie with oblique seismic profile in (c) indicated. U, an unconformity; LM, Laurentian Moraine; OLM, Outer Laurentian Moraine. Inset shows detail of the Laurentian Moraine. VE×123. Acquisition system 0.6 litre sleeve gun, single channel streamer. Frequency 150–650 Hz. ( c ) Oblique seismic-reflection profile from St Pierre Bank in the NW to Banquereau in the SE. Tie with longitudinal seismic profile in (b) indicated. Inset shows detail of till over unconformity. VE×26. Acquisition system air gun, single channel streamer. Frequency 150–650 Hz. ( d ) Multibeam …