LATEST PLEISTOCENE ICE-RAFTING EVENTS ON THE SCOTIAN MARGIN (EASTERN CANADA) AND THEIR RELATIONSHIP TO HEINRICH EVENTS

Piston cores from the continental margin off Nova Scotia show up to fo ur discrete intervals of ''brick-red sandy mud,'' which are up to 20 c m thick. The ages of these intervals are bracketed by several radiocar bon dates, and three fall in the range 12.5-14.1 ka (radiocarbon years with -0.4 kyr reservoir correction). The youngest dates from similar to 10.4 ka, placing it within the Younger Dryas. The distribution of t he beds and their petrographic character indicate a source in the Gulf of Saint Lawrence. The grain size of these beds suggests that they co mprise a coarse component transported by ice rafting that diminishes d istally and a fine component that represents suspension fallout from a surface plume and resulting nepheloid layers. Graded brick-red beds i n some cores were probably redeposited from turbidity currents. The lo wermost bed on the Laurentian Fan and East Scotian Rise is immediately overlain by a carbonate-rich interval that can be identified all arou nd the margin of the Grand Banks. This interval is correlated with det rital carbonate bed DC-1 in the Labrador Sea and Heinrich event H1 in the North Atlantic. The sequential occurrence of the two beds suggests that they may be a response to the same trigger, probably sea level r ise, but that the Gulf of Saint Lawrence source was more easily destab ilized.