Holocene and Latest Glacial Paleoceanography in the North-Eastern Skagerrak

• Main Author: Gyllencreutz, Richard
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Stockholms universitet, Institutionen för geologi och geokemi 2005
• Subjects: Skagerrak; Holocene; sediment; chirp sonar; grain size; mineral magnetic properties; Earth sciences; Geovetenskap; north atlantic current; North Atlantic
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-413

Detailed information on past oceanographic and climatic changes is crucial for our understanding of natural climate variability and for the assessment of future climate variations. Sediments strongly influenced by the North Atlantic Current accumulate at high rates in the northeastern Skagerrak, forming a potential highresolution archive for information on past climatic and oceanographic processes and events. Through a highresolution, multi-proxy study of the 32 meter long core MD99-2286 from the north-eastern Skagerrak, and interpretation of chirp sonar profiles from the coring area, this thesis provides new and detailed insights about the paleoceanographic development of the eastern North Sea region since the deglaciation. The chronostratigraphic control of core MD99-2286 relies on 27 radiocarbon dates. Ages are presented in calibrated thousand years before present (abbreviated “kyr”). Core MD99-2286 was correlated to chirp sonar profiles using measured physical properties. This correlation demonstrates that a strong regional acoustic reflector, previously assumed to represent the Pleistocene/Holocene boundary, was formed as a result of rapid ice retreat during the latest Pleistocene. Based on the distribution of ice rafted debris in the core, ice berg calving in the Skagerrak ended at 10.7 kyr. Detailed grain-size analyses of the core were interpreted using a novel 3D-visualization technique. Between 11.3 and 10.3 kyr, clay-rich distal glacial marine sediments were deposited in the northeastern Skagerrak, derived from Baltic melt-water outflow across south-central Sweden through the Otteid-Stenselva strait. As a result of differential isostatic uplift, the route of the major outflow and the associated sediment deposition moved southwards along the Swedish west coast. After 10.3 kyr, sediment deposition in the north-eastern Skagerrak gradually adopted to a fully interglacial normal marine sedimentation dominated by Atlantic inflow and the North Jutland Current. The establishment of the modern circulation ...