SEDIMENT DELIVERY AND ICE SHEET DYNAMICS AROUND BAFFIN BAY FOR THE LAST 40 KYRS

Baffin Bay has a complicated glaciation history having been surrounded by three major ice sheets over the last glacial – interglacial cycle, the Greenland (GIS), Laurentide (LIS) and Innuitian (IIS) ice sheets. Here we use a multi-proxy dataset (radiocarbon dating, X-ray fluorescence, X-ray diffraction, rare earth elements - REEs, foraminifera, ice rafted debris, osmium isotopes - ¹⁸⁷Os/¹⁸⁸Os and δ¹⁸O ice core records) from a central Baffin Bay marine sediment core to reconstruct the paleoceanography of Baffin Bay and the influence from surrounding ice sheets over the last ~40 kyrs.

Our results reveal two calcium peaks in the core denoting Baffin Bay detrital carbonate (BBDC) layers BBDC1 and BBDC0 with a known Paleozoic carbonate source from the IIS and the northeast LIS sector. Temporally coincident with the BBDC intervals are peaks in ¹⁸⁷Os/¹⁸⁸Os from which a second glacial source is identified. Using a mixing model and taking into account other data (e.g., REE characteristics and abundances), the peaks in ¹⁸⁷Os/¹⁸⁸Os are unlikely to be sourced from the Paleozoic terrains in northern Canada providing the BBDC material, but are more characteristic of a radiogenic, felsic provenance. A potential source region are the Archean and Proterozoic cratons underlying the GIS, though a contribution from similar aged geological terrains underlying the eastern LIS ice streams, e.g., Baffin Island, cannot be ruled out. The BBDC and radiogenic layers are broadly coincident with the Bølling-Allerød and Older Dryas (BBDC1) and the Younger Dryas (BBDC0) showing that the surrounding ice sheets responded in a largely synchronous manner to North Atlantic climate variations. Yet, during BBDC0 the delivery of glacially eroded material from the GIS, and possibly the LIS, appears to firstly lead that of the IIS by ~400 years and then diminish midway through the BBDC0 during which time the carbonate input remains high.

Interestingly our study reveals that ice sheet dynamics of both warmer (Bølling-Allerød - BBDC1) and cooler periods (Younger Dryas - BBDC0), can lead to influxes of glacially eroded material. Further, it suggests a relatively faster response of the GIS/LIS compared to the IIS to changes in climate during the Younger Dryas, relative to the penecontemporaneous ice sheet behavior of the Bølling-Allerød and Older Dryas - BBDC1.