SEDIMENT DELIVERY AND ICE SHEET DYNAMICS AROUND BAFFIN BAY FOR 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.