Bre- og klimahistorien under deglasiasjonen ved Nykvåg, Vesterålen

• Main Author: Rolland, Ane Netland
• Format: Master Thesis
• Language: Norwegian Bokmål
• Published: The University of Bergen 2020
• Subjects: Naturgeografi; Brerekonstruksjon; Vesterålen; Sedimentkjerne; Paleoklima; Deglasiasjonen; Klima; 733111; Dalvatnet; Lundvatnet; Nykdalen; Nykvåg; Skogvoll; Fennoscandian; Ice Sheet
• Online Access: https://hdl.handle.net/1956/23127

In this study, the late glacial climate history in Nykvåg, Vesterålen, is reconstructed. The reconstruction is based on geomorphological mapping in combination with high-resolution analysis of lake sediments from the former proglacial lake Dalvatnet. The extent of the Fennoscandian ice sheet in the area is defined based on the geomorphological mapping and the presence of erratics. In the outer part of the valley, three marginal moraines representing the maximum extent of the ice sheet, have been identified. The moraines represent glacial events which are referred to as Nykvåg event I, II and III. These events are tentatively correlated with the Endleten event (22,2-18,6 cal. ka BP), the Flesen event (18-17,5 cal. ka BP) and the Skogvoll event (16,9-16,3 cal. ka BP). It is suggested that the Fennoscandian ice sheet coalesced with a local valley glacier close to Lundvatnet during LGM. Local glacier fluctuations are reconstructed from Oldest Dryas to the start of the Holocene (16,435 ± 255-10825 ± 245 cal. yr BP), based on multi-proxy analysis of lacustrine sediments. The base of the core is characterized by high minerogenic input reflecting significant glacial activity in the catchment during the deposition of the sediments. The glaciers most likely melted away during the interstadial Bølling, followed by a period with increased glacial activity, which is linked to a glacial readvance during Older Dryas. Allerød is reflected in the core as a period with a general decrease in glacial activity. This is interrupted by two glacial readvances, which represents Intra-Allerød Cold Period (IACP) and Late Allerød Cooling (LAC). The onset of Younger Dryas (YD) is reflected in the lacustrine sediment record with gradual increase in glacial activity. Mid- to late YD is characterized by great variability in glacial activity. One of the most pronounced glacial advances in Nykdalen during the deglaciation is registered at the end of YD. The glaciers in Nykdalen ablated during the transition period between YD and the Holocene. ...