Late Glacial and Holocene Glacier Activity in Arctic Norway. Reconstruction of glacier fluctuations using surface exposure dating of moraines and multi-proxy analysis of sediments deposited in distal glacier-fed lakes

• Published in: Quaternary Science Reviews
• Main Author: Wittmeier, Hella Elisa
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: The University of Bergen 2014
• Subjects: Antarctic; Arctic; Dryas Glacier; Ela; Langfjordjøkelen; Norway; Rødhetta; Antarc*; Arnøya; glacier; Ice cap; North Atlantic
• Online Access: https://hdl.handle.net/11250/2754504

Late Glacial and Holocene glacier activity in Arctic Norway was reconstructed based on high-sensitivity 10Be dating of a moraine sequence deposited by the mountain glacier Rødhetta on the island of Arnøya, and a study of sediments deposited in several distal glacier-fed lakes located down the valley from the northern outlet of the Langfjordjøkelen ice cap on the Bergfjord Peninsula. In Paper I, we present the first comprehensive Late Glacial through Holocene 10Be dated mountain glacier moraine chronology in Arctic Norway. We show that temperature-sensitive mountain glaciers in Arctic Norway reached their maximum Late Glacial extent about 1000 years prior to the onset of the Younger Dryas. Following considerable retreat, glaciers re-stabilized about 12.3 ka ago, showing oscillatory retreat through the rest of the Younger Dryas stadial with the final culmination about 11.5 ka ago. The Younger Dryas glacier advances were significantly smaller in amplitude than the earlier Late Glacial culmination. No subsequent culminations took place during the Holocene until the Little Ice Age. The presented chronology of the Arctic mountain glacier is complemented by the glacier modeling results. The Equilibrium Line Altitude (ELA) lowerings compared to present day related to each moraine are as follows: Late Glacial ~220 m, Younger Dryas ~130 m, and Little Ice Age ~80 m. The most likely climate conditions during the moraine formation periods are represented by summer temperature cooling compared to present-day by ~3.2 °C during the Late Glacial culmination, by ~1.9 °C during the Younger Dryas, and by ~0.8 °C during the Little Ice Age. We show that this pattern is consistent with updated glacier records in the North Atlantic region, with suggested peak Late Glacial ice during the Bølling-Allerød/Antarctic Cold Reversal interval, a considerably smaller culmination early in the Younger Dryas stadial, and slight glacier retreat throughout the Younger Dryas. To explain this Late Glacial pattern and its similarity to southern ...