Ice sheets, oceanic circulation & sea surface conditions: the NW European margin during the last 35,000 years

The north-western European continental margin provides a key area for detailed investigations of changes within the inflow of Atlantic warm surface currents, fluctuations in continental ice sheets and the corresponding influence on sea surface conditions, such as (near) sea surface temperature and p...

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Bibliographic Details
Published in:Sedimentology
Main Author: Becker, Lukas
Format: Doctoral or Postdoctoral Thesis
Language:English
Published: The University of Bergen 2018
Subjects:
Online Access:https://hdl.handle.net/1956/17689
Description
Summary:The north-western European continental margin provides a key area for detailed investigations of changes within the inflow of Atlantic warm surface currents, fluctuations in continental ice sheets and the corresponding influence on sea surface conditions, such as (near) sea surface temperature and primary productivity. Knowledge of these fluctuations and forcing mechanisms is crucial to further our understanding of present day climate changes. This dissertation is principally based on continental slope cores, combined with shallow seismic lines and instrumentally measured data. The studied time interval is twofold, the last glacial cycle (35,000 - 15,000 years BP) and the mid- and late Holocene (the last 8000 years). During the last glacial cycle, the northwestern European margin was exposed to the advancing and retreating continental ice sheets, resulting in thick glacial, hemipelagic deposits on the continental slope that provide a continuous sedimentary archive of ice sheet build-up, maximum and decay. In contrast, the mid- and late Holocene encompassed relatively stable climatic conditions, with unusually high accumulation rates on the mid-Norwegian margin, allowing for a high-resolution analysis of the regional sea surface conditions. In addition, this dissertation presents a new automated procedure for counting ice rafted debris (IRD), providing a faster, more precise alternative method compared to the current manual counting technique utilised by numerous palaeo-environmental studies. The multi-proxy approach of this thesis was achieved through a set of different analytical techniques, ranging from X-ray fluorescence core scanning, to grain size analysis and foraminifera assemblage counts to numerical analysis and seismic interpretation. The complex ice-ocean interaction along the NW European continental margin during the last glacial cycle and the more recent oceanographic changes observed in the Holocene are chronologically constrained through numerous new and published radiocarbon and 210Pb/137Cs dated ...