Hudson Strait ice streams: a review of stratigraphy, chronology and links with North Atlantic Heinrich events |
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| Authors: | John T Andrews Brian MacLean |
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| Abstract: | We review the literature on the occupation of Hudson Strait (800?km long by 90?km wide) by late Quaternary ice streams, and the importance of Hudson Strait as the major source for sediments associated with the North Atlantic Heinrich (H-) events. Glacial erosion of the Paleozoic outcrop on the floor of Hudson Strait and Ungava Bay resulted in the export of detrital carbonate-rich sediments to ice-proximal locations on the slope and floor of the NW Labrador Sea, mainly in meltwater and turbidite plumes, and to ice distal sites thousands of kilometres away largely as iceberg-rafted detritus (IRD). Erosion of bedrock from the Precambrian Superior and Churchill provenances of the Canadian Shield is also indicated by the isotopic analyses of sediments. The major late Quaternary H-events (H-4, H-2 and H-1) are represented in southeast Baffin Island slope sediments as detrital carbonate-rich intervals up to 40?cm in thickness and appear to represent flow along the axis of the Strait. However, the late marine isotope stage #3 event, H-3 (～27?ka), and a younger event (H-0, ～11?ka), are not as dominant in the sedimentary record and probably represent a different glaciological regime with flow across Hudson Strait from eastern Ungava-Labrador. The freezing-on of sediments by supercooling in the rise from the 900?m deep Eastern Basin to the 400?m sill is proposed as the source of the abundant carbonate-rich glaciomarine sediments some 250?km from the outcrop in Eastern Basin. Sediment transport by meltwater and turbidity currents was the major process during H-events in ice-proximal settings. IRD was not a key diagnostic process at sites fronting Hudson Strait. A key feature in the instability of this ice stream might be the great depth (600?m) at the shelf break, and the deep basin, which lies seaward of the outer Hudson Strait sill. |
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