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Ice-sheet sourced juxtaposed turbidite systems in Labrador Sea

Geoscience Canada

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Abstract

Ice-sheet sourced Pleistocene turbidite systems of the Labrador Sea are different from non-glacially influenced systems in their facies distribution and depositional processes. Two large-scale sediment dispersal systems are juxtaposed, one mud-dominated and associated with the Northwest Atlantic Mid-Ocean Channel (NAMOC), the other sand-dominated and forming a huge submarine braided sandplain. Co-existence of the two systems reflects grain-size separation of the coarse and fine fractions on an enormous scale, caused by sediment winnowing at the entrance points of meltwater from the Laurentide Ice Sheet (LIS) to the sea (Hudson Strait, fiords) and involves a complex interplay of depositional and redepositional processes. The mud-rich NAMOC system is multisourced and represents a basinwide converging system of tributary canyons and channels. It focusses its sand load to the central trunk channel in basin centre, in the fashion of a "reverse" deep-sea fan. The sand plain received its sediment from the Hudson Strait by turbidity currents that were generated either by failure of glacial prodelta slopes at the ice margin, or by direct meltwater discharges with high bedload concentration. We speculate that the latter might have been related to subglacial-lake outburst flooding through the Hudson Strait, possibly associated with ice-rafting (Heinrich) events.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Ice-sheet sourced juxtaposed turbidite systems in Labrador Sea
Series title:
Geoscience Canada
Volume
24
Issue:
1
Year Published:
1997
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Geoscience Canada
First page:
3
Last page:
12
Number of Pages:
10