Paper No. 81-16
Presentation Time: 9:00 AM-5:30 PM
LATE QUATERNARY VARIATIONS IN SEDIMENT MINERALOGY AND GRAIN-SIZE ON THE NORTHERN BAFFIN ISLAND SLOPE: INSIGHTS INTO THE GLACIAL HISTORY OF BAFFIN BAY
The late Quaternary (Wisconsin) history of the NE Laurentide Ice Sheet (LIS) has been the subject of research since 1960. Radiocarbon dates initially suggested a limited expansion of the ice sheet terminating in the fjords, but subsequent cosmogenic dating suggests that a cold-based ice sheet spread seaward across the forelands. It is uncertain how far ice advanced across the continental shelf. If the LIS reached the shelf break then we would expect that glacial erosion would deliver sediments imprinted with the signature of the upstream bedrock - in this case felsic-rich Paleoproterozoic igneous and metamorphic rocks. Conversely, the large ice streams at the head of Baffin Bay flow over Paleozoic carbonate bedrock, and ice-rafted clasts and finer-grained sediments would transport detrital carbonate (DC) laterally along the Baffin Island slope. DC sediments also could be transported from Foxe Basin, across Baffin Island to Home Bay by the “Home Bay Ice Stream” (HBIS). In order to examine late Quaternary scenarios we studied quantitative mineralogy, counts of clasts > 2 mm, and sediment grain size in sediment cores from the Baffin Island slope collected by CCGS Hudson and compared them with sediments collected from large trough mouth fans on the West Greenland slope. We studied Baffin Island slope cores 061, 064, 073, 074 and 077 from cruise HU2013029 for comparison with the well-dated HU2008029-012 core from the West Greenland Disko Trough Mouth Fan. Based on color, IRD content, grain-size, and visible structures a total of twenty-five lithofacies were identified on cores from HU2013029. All cores record a tan DC unit that marks the onset of deglaciation and the incursion of warm Atlantic Water dated ~14 ± cal ka BP (ΔR = 0). HU2013029-077, taken in 1153 m water depth east of the probable terminus of the HBIS, has 5 lithofacies, and contains 4 older DC events, within laminated muds, that lack the upper tan color. The relative amounts of dolomite and calcite in these events suggest a possible input from Foxe Basin. The laminated muds in core 077, > 14 ± cal ka BP, may be indicative of an ice shelf that restricted iceberg transport. A possible radiocarbon date from the base of this 650 cm core is being prepared but foraminifera are scarce.