From early Miocene to present: Reconstruction of the deep Thermohaline Circulation at the Eirik Drift

• Main Author: Müller-Michaelis, Antje
• Other Authors: Stein, Rüdiger, Uenzelmann-Neben, Gabriele, Huhn, Katrin
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Universität Bremen 2014
• Subjects: Sediment Drift; Labrador Sea; North Atlantic Deep Water (NADW); Western Boundary Undercurrent (WBUC); North Atlantic Thermohaline Circulation; North Atlantic climate; 550; 550 Earth sciences and geology; ddc:550; Greenland; Denmark Strait; Greenland-Scotland Ridge; NADW; Nordic Seas; North Atlantic Deep Water; North Atlantic; North atlantic Thermohaline circulation
• Online Access: https://media.suub.uni-bremen.de/handle/elib/635; https://nbn-resolving.org/urn:nbn:de:gbv:46-00103689-14

The Thermohaline Circulation (THC) distributes heat and freshwater around the global oceans, interacts with the atmosphere, and therefore is closely connected to the global climate. The deep branch of the North Atlantic THC mainly consists of deep-water formed by atmospheric cooling in the Nordic Seas, which overflows the Greenland-Scotland Ridge into the North Atlantic. The Eirik Drift south of Greenland is located closely downstream of the North Atlantic deep-water formation region and has been shaped by the Western Boundary Undercurrent (WBUC), which constitutes the main part of the deep North Atlantic THC. The sedimentary record of the Eirik Drift documents changes of the WBUC activity, which can be related to climate changes. The analysis of the sedimentary structure in combination with geological information from scientific drilling leads to a revised seismostratigraphic concept at the Eirik Drift and reveals particularly that the Eirik Drift has been influenced by the WBUC already since the early Miocene (~19 Ma). A more detailed structural analysis of the depocenter locations and their redistribution results in a temporal reconstruction of the deep paleocirculation at the Eirik Drift. The observed changes of pathways and intensity of the WBUC at the Eirik Drift were linked to the development of the Greenland-Scotland Ridge and climate changes. The onset of drift building at the Eirk Drift followed the formation of the Faroe Conduit in early Miocene, which allowed northern sourced deep-water to overflow the eastern part of the Greenland-Scotland Ridge. A separation of the WBUC at the Eirik Drift into two branches occurred contemporaneously with the onset of deep-water overflow at the Denmark Strait, the western part of the Greenland-Scotland Ridge (~7 Ma). At the Eirik Drift, strong WBUC activity is inferred to occur during warm climates and at the beginning of cooling phases, while cooling phases with enhanced ice extent are characterized by weak WBUC activity. Based on a combination of these ...