Holocene variability of surface and seep water advection to the Arctic Ocean - a multiproxy perspective from the aastern Fram Strait

• Main Author: Werner, Kirstin
• Format: Thesis
• Language: English
• Published: 2011
• Subjects: Arctic; Arctic Basin; Arctic Ocean; Fram Strait; Greenland; North Atlantic; Sea ice; Svalbard
• Online Access: https://oceanrep.geomar.de/id/eprint/13244/; https://oceanrep.geomar.de/id/eprint/13244/1/diss.werner.pdf%3Bjsessionid%3D6E0BA615057D3AC774AA0DA6EB552997.pdf; http://macau.uni-kiel.de/servlets/MCRFileNodeServlet/dissertation_derivate_00004033/KWerner_Summary.pdf?hosts=&

Micropaleontological, geochemical, and sedimentological parameters of two sediment cores from the eastern Fram Strait have been studied to reconstruct the variability of surface and deep water advection and related fluctuations of the marginal ice zone during the past ca ∼9,000 years with multidecadal resolution. The Fram Strait between Greenland and Svalbard is the only deep connection between the Arctic and adjacent subpolar oceans and is often referred to as the ‘Arctic Gateway’. Fram Strait thus plays a crucial role for the energy budget and density pattern of the Arctic Ocean. Large amounts of warm and saline Atlantic Water derived from the North Atlantic Drift transport most of the heat through eastern Fram Strait to the Arctic basin, resulting in year-round ice-free conditions. Arctic sea ice and cold and fresh waters exit the western part of the strait southward along the Greenland shelf. Compared to the ice-covered Arctic Ocean, the strong east-west temperature gradient results in higher bioproductivity and sedimentation rates in the eastern Fram Strait which allows for suitably tracking Holocene variations of the heat flux to the Arctic Ocean in continuous high-resolution sediment sequences. The multiproxy results presented in this thesis suggest that the Holocene climate and oceanographic development in the Fram Strait and possibly the Arctic Ocean was much more variable than previously assumed. The variation and interaction between warm and saline advection of Atlantic Water at the surface to subsurface into the Arctic Ocean and a correspondingly fluctuating sea ice margin characterise the eastern Fram Strait throughout the Holocene. The data imply that the transition from deglacial/Early Holocene to modern-like conditions occurred stepwise. Inferred from the high relative abundance of the subpolar planktic foraminifer species Turborotalia quinqueloba, intense advection of warm Atlantic Water to the Arctic Ocean marks the Early and Mid-Holocene interval (~9,000 to 5,000 years before present), ...