In the wake of deglaciation - sedimentary signatures of ice-sheet decay and sea-level change : Studies from south-central Sweden and the western Arctic Ocean

• Main Author: Swärd, Henrik
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Stockholms universitet, Institutionen för geologiska vetenskaper 2018
• Subjects: paleoenvironmental changes; last deglaciation; sedimentology; Lake Vättern; western Arctic Ocean; Mackenzie Trough; Herald Canyon; Earth and Related Environmental Sciences; Geovetenskap och miljövetenskap; Geology; Geologi; Geosciences; Multidisciplinary; Multidisciplinär geovetenskap; Arctic; Arctic Ocean; Beaufort Shelf; Bering Strait; Chukchi Sea; MacKenzie Trough; Pacific; Chukchi; Fennoscandian; Ice Sheet
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-153906

Lacustrine and marine sedimentary archives help unravel details concerning the withdrawal of large ice sheets and resulting sea-level changes during the last deglaciation (22 -11 kyr). In a series of four manuscripts, this PhD thesis investigates the sedimentological signatures from deglacial processes at three key locations in the northern hemisphere: (i) Lake Vättern (LV) in south-central Sweden, (ii) Herald Canyon (HC) in the western Chukchi Sea, and (iii) Mackenzie Trough (MT) on the westernmost edge of the Canadian Beaufort Shelf. One lacustrine (LV) and two marine (HC and MT) sediment cores were analyzed using a broad range of methods to describe the physical, chemical, mineralogical and biological characteristics, and used to construct paleoenvironmental interpretations. Constituting the westernmost part of the Baltic Sea during parts of the last deglaciation, LV has long been envisaged as a key region for deglacial studies in southern Scandinavia. Sediments in LV highlight four major lake development stages following the withdrawal of the Fennoscandian Ice Sheet. These include the Baltic Ice Lake, the Yoldia Sea, the Ancylus Lake and the ultimate isolated lake stage. New radiocarbon dates indicate that the lake became isolated at 9530±50 cal. yr BP. A sharp transition from a varved clay unit to a partly sulfide laminated clay unit marks the final drainage of the Baltic Ice Lake, dated to 11 650±280 cal. yr BP. However, an earlier peak in pore water chlorinity identified in the sediment provides the most compelling evidence to date for an initial drainage of the Baltic Ice Lake (~12.8 cal. kyr BP) near the onset of the Younger Dryas cold event. Located downstream from where Pacific water flows into the Arctic, HC is a key location for understanding the details of the early Holocene (~11 cal. yr BP) flooding of the Bering Strait, and investigating sedimentological proxies for Pacific water in Arctic Ocean sediment cores. The deglacial transgression of the shelf and opening of the Bering Strait is reflected ...