Continental shelf glaciations off Northeast Greenland since the late Miocene

Abstract. Amplified Arctic warming is triggering dramatic changes to the Greenland Ice Sheet (GrIS). Studying past warm periods can provide process insights valuable to predictions of future ice sheet response. Miocene (23.03 – 5.33 Ma) and Pliocene (5.33 – 2.58 Ma) global climatic records include periods of warmer than present temperatures thought to represent analogues to near-future scenarios. Despite this, the details of the long-term glacial history of the eastern and northeastern sectors of Greenland are still largely unresolved. Here, we use seismic reflection and borehole data to describe the late Cenozoic glacial architectural development of the Northeast Greenland continental margin and thereby reconstruct long-term ice sheet evolution. We identify three key unconformable seismic surfaces that define three mega units of predominantly glacial origin. Two of the surfaces are for the first time correlated across the entire outer Northeast Greenland margin and tied to both Ocean Drilling Program Sites 909 and 913. We show that the late Miocene onset of shelf progradation occurs around 6.4 Ma, marking the first recorded advance of grounded ice masses across the NE Greenland shelf, forming depocentres (trough mouth fans) beyond the palaeo-shelf edge. Subsequently during the late Miocene and early Pliocene, the GrIS expands multiple times across the shelf, extending the continental shelf seawards. Based on the development of more extensive and thicker depocentres along the entire outer shelf and upper slope, we suggest an intensification of shelf glaciations after ~4.1 Ma, possibly coinciding with the intensification of the Northern Hemisphere glaciations (3.6 – 2.7 Ma).