Northeast Atlantic Cenozoic paleobathymetry and Iceland mantle plume activity: Influences on oceanic gateways and paleoocean circulation

• Main Author: Straume, Eivind Olavson
• Format: Master Thesis
• Language: English
• Published: 2016
• Subjects: Antarctic; Greenland; The Antarctic; Antarc*; Greenland-Scotland Ridge; Iceland; NADW; North Atlantic Deep Water; North Atlantic; Northeast Atlantic
• Online Access: http://hdl.handle.net/10852/52662; http://urn.nb.no/URN:NBN:no-56091

On geological time scales, the global ocean circulation is controlled by changes in paleobathymetry, including opening and closure of strategic ocean gateways and formation of new ocean basins. In the Cenozoic time (65 - 0 Ma), changes in ocean circulation related to tectonic changes presumably played an important role, along side with decreasing CO2 in the atmosphere, in the complex climatic evolution from a «greenhouse» climate with high polar temperatures to a cold «icehouse» climate with glaciated polar regions. This study aims to capture the role of paleobathymetry in times of profound changes in Earth’s climate through a series of paleobathymetric reconstructions, especially focusing on the NE Atlantic region where the Iceland Plume has modified the depth and morphology of the seafloor. Global paleobathymetry is reconstructed for six different Cenozoic times (at 52 Ma, 47 Ma, 41 Ma, 33 Ma, 15 Ma and 12 Ma) with a focus on detailed reconstructions of the NE Atlantic region. The paleobathymetric reconstructions benefits from an updated kinematic model and new seafloor age grids and also detailed reconstructions of the continental margins in the NE Atlantic region. The Greenland-Scotland Ridge (GSR) in the NE Atlantic may have functioned as transient ocean gateway influenced by temporal temperature fluctuations in the Iceland Plume controlling the amount of deep water flowing over the ridge which contribute to the North Atlantic Deep Water (NADW). The effects of closing the GSR are investigated using the Massachusetts Institute of Technology general circulation model (MITgcm). It is found that closing the GSR reduces the strength of the Atlantic Meridional Overturning Circulation (AMOC). It also has a profound effect on the strength of the Antarctic Circumpolar Current (ACC).