Palaeoenvironment of the Barents Sea during the last deglaciation and Holocene : processes and timing

Abstract

The scope of this PhD thesis is twofold: Firstly, processes, patterns and timing of the last deglaciation in the Barents Sea are reconstructed and secondly, depositional conditions on the Barents shelf during Holocene are elucidated. This cumulative PhD thesis encompasses an introductory part and five papers - three as first-author and two as co-author. Three papers are focused on the most prominent geomorphological freature of the western Barents shelf, 850 km long cross-shelf trough Bjørnøyrenna (The Bear Island Trough). One detailed study examines processes and timing of the first step of glacial retreat in outer Bjørnøyrenna and establishes a minimum age of 17 cal ka for initial deglaciation. A second study focuses on a grounding line system in uppermost Bjørnøyrenna, witnessing a surge-type readvance towards the final collapse of the marine-based Barents Sea Ice Sheet. A third study focuses on contrasting ice stream flow regimes and processes observed from glacial maximum over initial deglaciation towards final deglaciation. Two additional studies are located in the relatively small formerly glaciated trough Kveithola, north-west of Bjørnøya (Bear Island). The first focuses on the most recent deglaciation history and establishes an indirect deglaciation age for Spitsbergenbanken 14.2-13.9 cal ka ago. The other reconstructs the complex glacial retreat through Kveithola and associated processes based on geophysical data. As a whole, this PhD thesis improves existing chronology during deglaciation and Holocene for the Barents Sea, advances existing depositional models of ice-marginal and deglacial processes as well as it adds to established conceptional models of glacial retreat. While presented Holocene data is less conclusive, it might create the awareness that the large Storegga tsunami at 8.2 cal ka may have had an erosional impact on shelf sediments and thereby motivate further research.