Reconstructing Pliocene climatic, oceanic and tectonic interactions in the North East Atlantic, Nordic Seas and onshore Iceland by geochemical fingerprinting of marine and terrestrial sediments

• Main Author: Hall, Jonathan Richard
• Other Authors: Jones, Stephen, Dunkley Jones, Tom, Bendle, James, nerc
• Format: Thesis
• Language: English
• Published: 2021
• Subjects: QE Geology; Tjörnes; Iceland; Nordic Seas; North East Atlantic
• Online Access: http://etheses.bham.ac.uk//id/eprint/11460/7.hassmallThumbnailVersion/Hall2021PhD.pdf; http://etheses.bham.ac.uk//id/eprint/11460/; http://etheses.bham.ac.uk//id/eprint/11460/7/Hall2021PhD.pdf

During the Pliocene (5.33−2.58 Ma), the NE Atlantic and Nordic Seas witnessed a transition from enhanced warming, whereby surface temperatures were up to 8°C warmer than present, to cooling associated with the intensification of the Northern Hemisphere Glaciation. Currently, there are few reliable multiproxy datasets to document this change, and a notable mismatch between data- and model-based temperature reconstructions. This thesis develops a new palaeoclimatic, palaeoceanographic and palaeogeographic understanding of this region during the Pliocene by geochemical fingerprinting of marine and terrestrial sediments. First, new benthic foraminifera δ\(^{13}\)C and authigenic εNd records are used to assess tectonic and climatic controls on deep-water connectivity between the NE Atlantic and Norwegian basins. Secondly, new alkenone and TEX86 records are used to evaluate the magnitude of warming, and to unravel whether data/model discrepancies are attributable to proxy biases. Thirdly, brown coals from the Pliocene Tjörnes Beds in northern Iceland are investigated to establish whether they preserve branched GDGTs capable of reconstructing terrestrial temperatures. Together, these results suggest climatic events are at least as important as tectonic events in driving regional oceanic circulation at this time, and reveal data/model discrepancies are influenced by warming biases, associated with the analysis of low concentration alkenones.