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Emmanuel Okuma

Institution: University of Bremen
Office: MARUM II, room 3150
Phone: +49 421 218 - 65658
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Emmanuel Okuma

PhD Project

Impacts of ocean-ice interactions on the Holocene sedimentary system in the western Baffin Bay

The Baffin Bay is a semi-enclosed basin between the Canadian Arctic Archipelago and Greenland. It represents a major pathway for southward-advecting relatively cold and fresh Arctic water and ice and northward-flowing relatively warm and dense North Atlantic waters, respectively driven by the Baffin Island and West Greenland Currents, and potentially play a crucial role in the North Atlantic circulation/climate system.

The opening of the Nares Strait and other channels in the Canadian Arctic Archipelago during early Holocene initiated the modern anti-cyclonic circulation in Baffin Bay and established it as an important site for water and heat exchange. Until this time, these Arctic channels were largely inundated by ice streams of the coalescent Laurentide, Innuitian, and Greenland Ice sheets during the Last Glacial Maximum. There has been a considerable increase in studies focused on the last deglaciation to Holocene climate development in Baffin Bay in the last decades. Paleoclimate reconstructions based on marine proxy records generally agree on a cold deglacial condition in the earliest Holocene, a major change to warmer condition through the middle Holocene and, the return of cold condition in later Holocene. Moreover, several results suggest major paleoenvironmental and paleoceanographic changes closely aligned with the Holocene thermal optimum and the Neoglacial period.

Depending on the overall climate setting in various phases of the Holocene, very different water and sediment routing systems may have affected sedimentation in Baffin Bay. Key pathways for waters, ice, and sediments are the Nares Strait, Lancaster Sound, and the Davis Strait, in addition to the huge amounts of sediments supplied from the surrounding landmasses. Understanding the interplay between Baffin Bay paleoceanography, the connectivity to the Arctic and North Atlantic Ocean, and the surrounding ice sheets through the Holocene will be crucial in gaining process understanding about the controls on water/sediment input to and bypassing through Baffin Bay.

Therefore, this project aims to budget Holocene sediment input to Baffin Bay and to investigate the mutual impacts of shrinking ice sheets and changing paleoceanography on sedimentation in Baffin Bay. I will apply a combination of sedimentological, geochemical, stratigraphical and micropaleontological methods to determine the timing, quantity, and quality of sediment input from the four major sources, to answer the following questions: (i) if a predominant global climate rather than regional forcing controls sediment input through Nares Strait and Lancaster Sound, (ii) if the signal of glacial erosion is directly transferred from land via the fjord to the open shelf, and (iii) if the contribution of the Laurentide, Innuitian, and Greenland Ice sheets to sedimentation in the Baffin Bay followed the same global change driven pattern through the Early Holocene. This project will improve our understanding of past climate changes in the northern high latitudes and its coupling-control on sedimentation and sediment supply.

Thesis Committee

Prof. Dr. Dierk Hebbeln MARUM - Center for Marine Environmental Sciences, University of Bremen
Prof. Dr. Markus Kienast Dalhousie University, Halifax, Canada
Prof. Dr. Rüdiger Stein University of Bremen and Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, Bremerhaven
Dr. Jürgen Titschack MARUM - Center for Marine Environmental Sciences, University of Bremen