“Late Quaternary ice sheet dynamics and palaeoceanography in the Baffin Bay region”

Abstract

There remains a lack of data surrounding the timings and dynamics of the initial retreat of the Greenland ice sheet (GIS) from its maximum extent at the end of the last glacial maximum (LGM), with poor chronostratigraphic constraint also present on the timings of major Baffin Bay detrital carbonate events (BBDC) during the last deglaciation. This study presents new high-resolution data from two cores extracted from the deep abyssal plain of central Baffin Bay. Two separate radiocarbon dates have been extracted using foraminifera which have been used in the development of an age-depth model; estimating the base of the longer gravity core ‘GC01’ to be approximately 22 ka in age. Samples adequate for radiocarbon dating are few and far between due to intense dissolution of biogenic carbonate in both cores. Measurements of elemental concentrations indicate that significant changes in sediment provenance occurred in central Baffin Bay over the last 22Ka. Substantial amounts of sediment influx from western Greenland occurred during the LGM until approximately 15.8 ka BP when the GIS began its initial stages of retreat as the marine area of Baffin Bay increased. Thereafter the use of sedimentological, geochemical and biological markers alongside radiocarbon dating has captured two separate periods of ice sheet instability associated with the BBDC 1 and BBDC 0 estimated to have occurred between 14.1-13.6 ka BP and 12.7-11.4 ka BP respectively. Further analysis of elemental concentrations attributes these two BBDC events to both be associated with large amounts of sediment influx from northern Baffin Bay i.e. the break-up of the Laurentide (LIS) and the Innuitian Ice Sheets (IIS). When plotted as a timeseries against GISP2 and NGRIP ice core records and regional records of marine palaeoenvironmental, change it is clear that BBDC 1 and BBDC 0 occur out-of-phase with Heinrich event 1 or Heinrich event 0. Instead, BBDC 1 appears to start during the later stages of the Bølling Interstadial and continue into the Allerød Interstadial, peaking during the Older Dryas Stadial. BBDC 0 is generally coeval with the Younger Dryas Stadial although likely ends before the start of Heinrich event 0 in the North Atlantic. Due to BBDC events occurring during both interstadials and stadials periods this would also suggest that the initial trigger for the start of BBDC events are not necessarily linked to temperatures changes on Greenland, supporting Jackson et al., 2017. Therefore, indicating that the LIS and IIS were likely decoupled from the North Atlantic climate mode during the last deglaciation.