Southern Greenland glaciation and Western Boundary Undercurrent evolution recorded on Eirik Drift during the late Pliocene intensification of Northern Hemisphere glaciation

Abstract

We present new sedimentological and environmental magnetic records spanning ∼3.2–2.2 Ma, during the intensification of Northern Hemisphere glaciation, from North Atlantic Integrated Ocean Drilling Program Site U1307 on Eirik Drift. Our new datasets and their high-fidelity age control demonstrate that while inland glaciers – and potentially also at times restricted iceberg-calving margins – have likely existed on southern Greenland since at least ∼3.2 Ma, persistent and extensive iceberg-calving glacial margins were only established in this region at 2.72 Ma, ∼300 kyr later than in northeastern and eastern Greenland. Despite a dramatic increase in Greenland-sourced ice-rafted debris deposition on Eirik Drift at this time, contemporaneous changes in the bulk magnetic properties of Site U1307 sediments, and a reduction in sediment accumulation rates, suggest a decrease in the delivery of Greenland-sourced glaciofluvial silt to our study site. We attribute these changes to a shift in depositional regime from bottom-current-dominated to glacial-IRD-dominated between ∼2.9 and 2.7 Ma, in response to a change in the depth of the flow path of the Western Boundary Undercurrent relative to our study site.