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Architecture and structural evolution of an early Little Ice Age terminal moraine at the surge-type glacier Mulajokull, Iceland

Benediktsson, Ivar Örn LU ; Schomacker, Anders; Johnson, Mark D.; Geiger, Alessa J.; Ingolfsson, Olafur and Guomundsdottir, Esther Ruth (2015) In Journal of Geophysical Research - Earth Surface 120(9). p.1895-1910
Abstract
The internal architecture and structural evolution of the Arnarfellsmular terminal moraine at Mulajokull, a surge-type glacier in central Iceland, is described in order to demonstrate submarginal and proglacial glaciotectonic processes during glacier surging, as well as constraining the age of the maximum extent of the glacier. The moraine is 4-7m high, 50-100m wide, and composed of a highly deformed sequence of loess, peat, and tephra that is draped by till up to the crest. The internal architecture is dominated by steep, high-amplitude overturned folds and thrusts in the crest zone but open, low-amplitude folds on the distal slope. Section balancing suggests a basal detachment (decollement) depth of 1.4m and a total horizontal shortening... (More)
The internal architecture and structural evolution of the Arnarfellsmular terminal moraine at Mulajokull, a surge-type glacier in central Iceland, is described in order to demonstrate submarginal and proglacial glaciotectonic processes during glacier surging, as well as constraining the age of the maximum extent of the glacier. The moraine is 4-7m high, 50-100m wide, and composed of a highly deformed sequence of loess, peat, and tephra that is draped by till up to the crest. The internal architecture is dominated by steep, high-amplitude overturned folds and thrusts in the crest zone but open, low-amplitude folds on the distal slope. Section balancing suggests a basal detachment (decollement) depth of 1.4m and a total horizontal shortening of around 59%. This implies that the glacier coupled to the foreland about 70m up glacier from its terminal position to initiate the formation of the moraine. The structural evolution is polyphase in that the formation commenced with low-amplitude open folding of the foreland, followed by overfolding and piggyback thrusting. Radiocarbon dating and analysis of tephra layers, along with historical references, indicate that the most likely time of moraine formation was between A.D. 1717 and 1760, which suggests that Mulajokull had its Little Ice Age maximum and most extensive surge earlier than many other surge-type glaciers in Iceland. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
glaciotectonic, moraine, folding and thrusting, horizontal shortening, surge-type glacier, Mulajokull
in
Journal of Geophysical Research - Earth Surface
volume
120
issue
9
pages
1895 - 1910
publisher
American Geophysical Union
external identifiers
  • wos:000363464200016
  • scopus:84944688604
ISSN
2169-9011
DOI
10.1002/2015JF003514
language
English
LU publication?
yes
id
95676078-d11f-4733-b226-a9927ca60794 (old id 8201600)
date added to LUP
2015-11-26 11:58:18
date last changed
2017-09-10 03:01:31
@article{95676078-d11f-4733-b226-a9927ca60794,
  abstract     = {The internal architecture and structural evolution of the Arnarfellsmular terminal moraine at Mulajokull, a surge-type glacier in central Iceland, is described in order to demonstrate submarginal and proglacial glaciotectonic processes during glacier surging, as well as constraining the age of the maximum extent of the glacier. The moraine is 4-7m high, 50-100m wide, and composed of a highly deformed sequence of loess, peat, and tephra that is draped by till up to the crest. The internal architecture is dominated by steep, high-amplitude overturned folds and thrusts in the crest zone but open, low-amplitude folds on the distal slope. Section balancing suggests a basal detachment (decollement) depth of 1.4m and a total horizontal shortening of around 59%. This implies that the glacier coupled to the foreland about 70m up glacier from its terminal position to initiate the formation of the moraine. The structural evolution is polyphase in that the formation commenced with low-amplitude open folding of the foreland, followed by overfolding and piggyback thrusting. Radiocarbon dating and analysis of tephra layers, along with historical references, indicate that the most likely time of moraine formation was between A.D. 1717 and 1760, which suggests that Mulajokull had its Little Ice Age maximum and most extensive surge earlier than many other surge-type glaciers in Iceland.},
  author       = {Benediktsson, Ivar Örn and Schomacker, Anders and Johnson, Mark D. and Geiger, Alessa J. and Ingolfsson, Olafur and Guomundsdottir, Esther Ruth},
  issn         = {2169-9011},
  keyword      = {glaciotectonic,moraine,folding and thrusting,horizontal shortening,surge-type glacier,Mulajokull},
  language     = {eng},
  number       = {9},
  pages        = {1895--1910},
  publisher    = {American Geophysical Union},
  series       = {Journal of Geophysical Research - Earth Surface},
  title        = {Architecture and structural evolution of an early Little Ice Age terminal moraine at the surge-type glacier Mulajokull, Iceland},
  url          = {http://dx.doi.org/10.1002/2015JF003514},
  volume       = {120},
  year         = {2015},
}