Southwest Greenland shelf glaciation during MIS 4 more extensive than during the Last Glacial Maximum

Marit-Solveig Seidenkrantz,Christof Pearce,Ian Snowball,Jesper Olsen,Johan Ploug,Piotr Przybyło,Antoon Kuijpers,Sofia Lindblom

doi:10.1038/s41598-019-51983-3

Abstract

Although geological and modelling evidence indicate that the last glacial inception in North America was in NE Canada, little is known about the glacial response of the nearby western Greenland Ice Sheet (GIS) during the glacial advance of marine oxygen isotope stage 4 (MIS4). Our multi-proxy study of a marine sediment core collected about 60 km southwest of the Outer Hellefisk Moraines demonstrates that in the southern Davis Strait region the most extreme Greenland shelf glaciation of the last glacial cycle occurred during MIS 4, with another prominent glacial advance at 37–33 kyr BP. During those periods the GIS likely reached the Outer Hellefisk Moraines in this area. Except for these two periods, our data suggest significant advection of relatively warm Irminger Sea Water by the West Greenland Current since MIS 4. This advection likely limited the extent of the MIS2 glaciation on the SW Greenland shelf. Decreased precipitation over southwestern Greenland predicted by atmospheric models as a downstream effect of a much larger MIS2 Laurentide Ice Sheet may have played an additional role.

Highlights

At the end of the last interglacial (Marine Isotope Stage (MIS) 5e) approximately 115,000 years ago (115 kyr BP, before present), the astronomically-driven decline of northern summer insolation and resulting atmospheric and ocean feedback processes led towards the first step in glacial ice sheet formation in the North American region[1]
Ca may originate from detrital carbonate, which is an important component of IRD in the study region[22], as is reflected in our Ca/Sr record (Fig. 2) which is a well-known proxy of non-biogenic carbonate[23]
Apart from a potential biogenic origin, Si is an important indicator of continent-derived material, and a terrestrial origin of the silica in core 479 G is strongly supported by its similarity to the K record

Summary

Introduction

At the end of the last interglacial (Marine Isotope Stage (MIS) 5e) approximately 115,000 years ago (115 kyr BP, before present), the astronomically-driven decline of northern summer insolation and resulting atmospheric and ocean feedback processes led towards the first step in glacial ice sheet formation in the North American region[1]. Been reported that during MIS 4, an extensive outer shelf glaciation occurred on the western Siberian shelf[6,7], while northern Siberian mountain glaciation was large[8] Both for MIS 4 and the preceding cold MIS5b substage (86.2 kyr model age) the size and location of the early glacial ice sheets could be reconstructed by a combination of geological information and numerical modelling[3]. Our investigations are based on a multi-proxy study based on sedimentological, geochemical, foraminiferal and stable isotope analyses from a marine sediment core, where sedimentological (in particular IRD) and elemental composition from XRF core scanning as well as magnetic properties will inform on the influx of sediments from terrestrial sources, whereas benthic foraminiferal assemblage data supported by planktonic stable isotope data are invaluable for identifying the environmental conditions and changes in ocean circulation

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Discussion

Conclusion