A High Resolution Chronology of Clastic Supply to the Central Baffin Bay during the Last Deglacial Ice Sheet Melting

English Abstract:

The Baffin Bay is a key region for understanding the interaction between ocean circulation and the Greenland Ice Sheet (GIS). Oceanic conditions in the basin are affected by the extent of seasonal sea-ice and changes in the inflow of water from the Labrador Sea and North Atlantic. The input of freshwater from the Arctic Ocean and meltwater from both the Canadian Arctic Archipelago and the GIS also plays an important role. All of these systems have been shown to vary on millennial and centennial timescales, and their state is predicted to change in response to the ongoing Arctic warming trend. However, the complex feedbacks and phase relationships between these systems, as well as how they respond to shifts in climate in the wider region, remain unclear.

During the last deglaciation, the region experienced large magnitude environmental change. We use this interval to investigate periods of increased clastic supply from the melting of the GIS, using two sediment cores from the central Baffin Bay. A novel preparation method allowing AMS 14-C dating of ultra-small samples (0.5 mg) has been used to generate a robust deglacial chronology in both cores. Here, we present profiles of sediment physical and chemical properties for both cores which provide, to date, the highest-resolution continuous record of terrigenous input for the central Baffin Bay, spanning the entire deglaciation.

Results indicate several intervals during which the composition of the clastic fraction shifts; the older episode of detrital input coincides with the timing of Heinrich Event 1 centred around 17ka BP. However, further through the deglacial, the chronology of detrital input appears to be out of phase with Greenland temperatures. An interval of elevated deposition, enhanced clastic supply and thus enhanced meltwater input began in the Younger Dryas stadial at 12.5 ka BP, indicating a fundamentally different relationship between ice-sheet derived clastic supply and Greenland temperature during the late deglacial period.