57-2 Following the Carbonate: Spatial Variability in Pleistocene Detrital Carbonate Beds from Baffin Bay to the Labrador Sea

Abstract:

Prominent, detrital carbonate-rich beds are widespread in latest Pleistocene piston cores in Baffin Bay and have been interpreted as recording basin-wide glacial variability; however, some uncertainty remains regarding their stratigraphic continuity, provenance, and depositional mechanisms. Here we characterize dozens of detrital carbonate beds recovered at ODP Sites 645, 646, and 647 in Baffin Bay and the Labrador Sea, extending the record into the Early Pleistocene to investigate their provenance and depositional history. This study integrates observations from high-resolution core photographs, granulometry, petrography, and stable isotope geochemistry to document spatiotemporal changes in composition and sedimentology. At these sites, the deposits are dominated by mud, with sand and gravel contents increasing toward Site 645, which is proximal to a potential carbonate source in the Canadian Arctic Archipelago, and decreasing toward the more distal Labrador Sea sites. Bulk carbonate δ¹⁸O and δ¹³C values differ between Baffin Bay and Labrador Sea sites. Site 645 beds are characterized by lower and more uniform values than those of beds from Sites 646 and 647. Spatial variability in the composition and sedimentology of detrital carbonate beds may reflect differences in source region, sediment sorting during transport, and/or depositional pathways. These findings provide new constraints on the provenance and depositional history of detrital carbonate beds and suggest that their composition and sedimentology should be considered when interpreting these deposits as regional records of Pleistocene ice-sheet variability.

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