TY - JOUR
T1 - Instantaneous end moraine and sediment wedge formation during the 1890 glacier surge of Brúarjökull, Iceland
AU - Benediktsson, Ívar Örn
AU - Möller, Per
AU - Ingólfsson, Ólafur
AU - van der Meer, Jaap J.M.
AU - Kjær, Kurt H.
AU - Krüger, Johannes
N1 - Funding Information: Financial support for the Brúarjökull project was provided by the Swedish National Research Council, the Royal Physiographic Society in Lund, the Crafoord Foundation, the Icelandic Research Council, the University of Iceland Research Fund, Landsvirkjun and the Danish National Research Council. The National Museum of Iceland and Sven Sigurðsson kindly provided access to and retrieved photographic material from the photo archive of Sigurður Þórarinsson. We express our sincere thanks to Anders Schomacker, Carita G. Knudsen, Svante Björck, Eiliv Larsen, Louise Ravn, Lilja Rún Bjarnadóttir, Jón Björn Ólafsson, Ida H.E.O. Jönsson and Silvana Correa Kjær for their companionship and collaboration during the 2003–2005 fieldwork at Brúarjökull. Í.Ö.B. acknowledges scholarships from Landsvirkjun, the Icelandic Research Fund for Graduate Students and the University of Iceland Research Fund. Thanks are due to one anonymous reviewer and Jim Rose for constructive and useful comments on the paper.
PY - 2008/2
Y1 - 2008/2
N2 - Contemporary understanding of the behaviour of surging glaciers and ice streams is hampered by the lack of data on landsystem evolution and sedimentary environments. This study concerns the ice-marginal environment of the surge-type Brúarjökull in Iceland. The sediment distribution in the glacier forefield as well as the morphology, sedimentology and tectonic architecture of the 1890 end moraine is investigated for highlighting the interaction between very dynamic ice and sediment/landform associations. As a result of substrate/bedrock decoupling during the 1890 surge, subglacial sediment was dislocated across the bedrock surface and deformed compressively, leading to gradual substrate thickening and the formation of a sediment wedge in the marginal zone. A drop in subglacial porewater pressure at the very end of the surge led to substrate/bedrock coupling and a stress transfer up into the sediment sequence causing brittle deformation of the substrate. Simultaneously, the glacier toe ploughed into the topmost part of the marginal sediment wedge initiating the moraine-ridge construction. Fine-grained and incompetent sediment deformed in ductile manner, resulting in a narrow moraine dominated by rooted folds, while coarse-grained and competent sediment deformed in brittle fashion, resulting in a wider moraine dominated by thrust blocks. A new sequential model of subglacial and ice-marginal processes operating during a glacier surge is proposed, illustrating the stepwise formation of a marginal sediment wedge and an end moraine-a twofold, inseparable marginal end-product that formed during the last days of the 1890 surge.
AB - Contemporary understanding of the behaviour of surging glaciers and ice streams is hampered by the lack of data on landsystem evolution and sedimentary environments. This study concerns the ice-marginal environment of the surge-type Brúarjökull in Iceland. The sediment distribution in the glacier forefield as well as the morphology, sedimentology and tectonic architecture of the 1890 end moraine is investigated for highlighting the interaction between very dynamic ice and sediment/landform associations. As a result of substrate/bedrock decoupling during the 1890 surge, subglacial sediment was dislocated across the bedrock surface and deformed compressively, leading to gradual substrate thickening and the formation of a sediment wedge in the marginal zone. A drop in subglacial porewater pressure at the very end of the surge led to substrate/bedrock coupling and a stress transfer up into the sediment sequence causing brittle deformation of the substrate. Simultaneously, the glacier toe ploughed into the topmost part of the marginal sediment wedge initiating the moraine-ridge construction. Fine-grained and incompetent sediment deformed in ductile manner, resulting in a narrow moraine dominated by rooted folds, while coarse-grained and competent sediment deformed in brittle fashion, resulting in a wider moraine dominated by thrust blocks. A new sequential model of subglacial and ice-marginal processes operating during a glacier surge is proposed, illustrating the stepwise formation of a marginal sediment wedge and an end moraine-a twofold, inseparable marginal end-product that formed during the last days of the 1890 surge.
UR - https://www.scopus.com/pages/publications/39149113468
U2 - 10.1016/j.quascirev.2007.10.007
DO - 10.1016/j.quascirev.2007.10.007
M3 - Article
SN - 0277-3791
VL - 27
SP - 209
EP - 234
JO - Quaternary Science Reviews
JF - Quaternary Science Reviews
IS - 3-4
ER -