Dynamics and glacial history of the Drangajökull ice cap, Northwest Iceland

• Main Author: Brynjólfsson, Skafti
• Other Authors: Anders Schomacker, Ólafur Ingólfsson, Jarðvísindadeild (HÍ), Faculty of Earth Sciences (UI), Verkfræði- og náttúruvísindasvið (HÍ), School of Engineering and Natural Sciences (UI), Háskóli Íslands, University of Iceland
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Norwegian University of Science and Technology; University of Iceland 2015
• Subjects: Jöklafræði; Setmyndun; Landmótun; Drangajökull; Doktorsritgerðir; glacier; Ice cap; Ice Sheet; Iceland
• Online Access: https://hdl.handle.net/20.500.11815/154

This thesis describes the glacial history, glacier dynamics, sediments and landforms of the Drangajökull ice cap as well as the glacial history and dynamics of the eastern Vestfirðir peninsula in northwest Iceland from the Late Weichselian until present. The aim was to reconstruct and improve the present understanding of the glacial history, surge history and dynamics of the Drangajökull ice cap. The results reveal a topographically controlled ice sheet which more and less covered the Vestfirðir peninsula during the last glaciation. Cold-based non-erosive sectors of the ice sheet covered most of the mountains while fjords and valleys were occupied by dynamical, warm-based ice. Ice thinning and deglaciation started over the mountain plateaux ca. 26 ka BP; the deglaciation was stepwise and asynchronous, uplands and some valleys were deglaciated 14-15 ka BP while valleys draining the main outlets of Drangajökull were occupied by outlet glaciers until c. 9 ka BP. The forefields proximal to the present Drangajökull ice cap are characterised by thin, coarse grained till and locally weathered bedrock, except for the sandur covered valley floors. The landforms mapped at the surging outlet glaciers are not unique for surging glaciers, and furthermore the mapped landform assemblage does not resemble landsystem models for surging glaciers. The surge-type outlets of Drangajökull reached their LIA maximum extent asynchronously during surges in the period ca. 1700-1846 AD. Review of historical data and geomorphological mapping revealed twice as many surges than previously recorded. The surge interval varies from 10-140 years between and within the outlets. Surges were most frequent during the 19th century and the earliest 20th century. No clear relationship between surge initiation or periodicity and climate could be established. A distinct ice discharge occurs during surges, reflected in 10-30 m surface thinning of the upper reservoir areas and 10-120 m thickening of the receiving areas. During the present quiescent phase, ...