Deciphering the evolution of the Bleis Marscha rock glacier (Val d'Err, eastern Switzerland) with cosmogenic nuclide exposure dating, aerial image correlation, and finite element modeling
<p>We constrain the Holocene development of the active Bleis Marscha rock glacier (Err–Julier area, eastern Swiss Alps) with 15 cosmogenic nuclide exposure ages (<span class="inline-formula"><sup>10</sup></span>Be, <span class="inline-formula">...
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doaj-47d936874e1344e0a28f409567055d052021-04-26T11:27:07ZengCopernicus PublicationsThe Cryosphere1994-04161994-04242021-04-01152057208110.5194/tc-15-2057-2021Deciphering the evolution of the Bleis Marscha rock glacier (Val d'Err, eastern Switzerland) with cosmogenic nuclide exposure dating, aerial image correlation, and finite element modelingD. Amschwand0D. Amschwand1S. Ivy-Ochs2S. Ivy-Ochs3M. Frehner4O. Steinemann5M. Christl6C. Vockenhuber7Department of Earth Sciences, ETH Zurich, 8092, Zurich, Switzerlandnow at: Department of Geosciences, University of Fribourg, 1700, Fribourg, SwitzerlandDepartment of Earth Sciences, ETH Zurich, 8092, Zurich, SwitzerlandLaboratory of Ion Beam Physics, ETH Zurich, 8093, Zurich, SwitzerlandDepartment of Earth Sciences, ETH Zurich, 8092, Zurich, SwitzerlandLaboratory of Ion Beam Physics, ETH Zurich, 8093, Zurich, SwitzerlandLaboratory of Ion Beam Physics, ETH Zurich, 8093, Zurich, SwitzerlandLaboratory of Ion Beam Physics, ETH Zurich, 8093, Zurich, Switzerland<p>We constrain the Holocene development of the active Bleis Marscha rock glacier (Err–Julier area, eastern Swiss Alps) with 15 cosmogenic nuclide exposure ages (<span class="inline-formula"><sup>10</sup></span>Be, <span class="inline-formula"><sup>36</sup></span>Cl), horizontal surface creep rate quantification by correlating two orthophotos from 2003 and 2012, and finite element modeling. We used the latter to separate the control on surface movement exerted by topography and material properties. Bleis Marscha is a stack of three overriding lobes whose formation phases are separated by time gaps expressed morphologically as over-steepened terrain steps and kinematically as a sharp downslope decrease in surface movement. The three discrete formation phases appear to be correlated to major Holocene climate shifts: Early Holocene low-elevation lobes (<span class="inline-formula">∼8.9</span>–8.0 ka, after the Younger Dryas), Middle Holocene lobe (<span class="inline-formula">∼5.2</span>–4.8 ka, after the Middle Holocene warm period), and Late Holocene high-elevation lobes (active since <span class="inline-formula">∼2.8</span> ka, intermittently coexisting with oscillating Bleis Marscha cirque glacierets). The formation phases appear to be controlled in the source area by the climate-sensitive accumulation of an ice-debris mixture in proportions susceptible to rock glacier creep. The ongoing cohesive movement of the older generations requires ice at a depth which is possibly as old as its Early–Middle Holocene debris mantle. Permafrost degradation is attenuated by “thermal filtering” of the coarse debris boulder mantle and implies that the dynamics of the Bleis Marscha lobes that once formed persisted over millennia are less sensitive to climate. The cosmogenic radionuclide inventories of boulders on a moving rock glacier ideally record time since deposition on the rock glacier root but are stochastically altered by boulder instabilities and erosional processes. This work contributes to deciphering the long-term development and the past to quasi-present climate sensitivity of rock glaciers.</p>https://tc.copernicus.org/articles/15/2057/2021/tc-15-2057-2021.pdf |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
D. Amschwand D. Amschwand S. Ivy-Ochs S. Ivy-Ochs M. Frehner O. Steinemann M. Christl C. Vockenhuber |
spellingShingle |
D. Amschwand D. Amschwand S. Ivy-Ochs S. Ivy-Ochs M. Frehner O. Steinemann M. Christl C. Vockenhuber Deciphering the evolution of the Bleis Marscha rock glacier (Val d'Err, eastern Switzerland) with cosmogenic nuclide exposure dating, aerial image correlation, and finite element modeling The Cryosphere |
author_facet |
D. Amschwand D. Amschwand S. Ivy-Ochs S. Ivy-Ochs M. Frehner O. Steinemann M. Christl C. Vockenhuber |
author_sort |
D. Amschwand |
title |
Deciphering the evolution of the Bleis Marscha rock glacier (Val d'Err, eastern Switzerland) with cosmogenic nuclide exposure dating, aerial image correlation, and finite element modeling |
title_short |
Deciphering the evolution of the Bleis Marscha rock glacier (Val d'Err, eastern Switzerland) with cosmogenic nuclide exposure dating, aerial image correlation, and finite element modeling |
title_full |
Deciphering the evolution of the Bleis Marscha rock glacier (Val d'Err, eastern Switzerland) with cosmogenic nuclide exposure dating, aerial image correlation, and finite element modeling |
title_fullStr |
Deciphering the evolution of the Bleis Marscha rock glacier (Val d'Err, eastern Switzerland) with cosmogenic nuclide exposure dating, aerial image correlation, and finite element modeling |
title_full_unstemmed |
Deciphering the evolution of the Bleis Marscha rock glacier (Val d'Err, eastern Switzerland) with cosmogenic nuclide exposure dating, aerial image correlation, and finite element modeling |
title_sort |
deciphering the evolution of the bleis marscha rock glacier (val d'err, eastern switzerland) with cosmogenic nuclide exposure dating, aerial image correlation, and finite element modeling |
publisher |
Copernicus Publications |
series |
The Cryosphere |
issn |
1994-0416 1994-0424 |
publishDate |
2021-04-01 |
description |
<p>We constrain the Holocene development of the active Bleis
Marscha rock glacier (Err–Julier area, eastern Swiss Alps) with 15
cosmogenic nuclide exposure ages (<span class="inline-formula"><sup>10</sup></span>Be, <span class="inline-formula"><sup>36</sup></span>Cl), horizontal surface
creep rate quantification by correlating two orthophotos from 2003 and 2012,
and finite element modeling. We used the latter to separate the control on
surface movement exerted by topography and material properties. Bleis
Marscha is a stack of three overriding lobes whose formation phases are
separated by time gaps expressed morphologically as over-steepened terrain
steps and kinematically as a sharp downslope decrease in surface movement. The
three discrete formation phases appear to be correlated to major Holocene
climate shifts: Early Holocene low-elevation lobes (<span class="inline-formula">∼8.9</span>–8.0 ka, after the Younger Dryas), Middle Holocene lobe (<span class="inline-formula">∼5.2</span>–4.8 ka, after the Middle Holocene warm period), and Late Holocene
high-elevation lobes (active since <span class="inline-formula">∼2.8</span> ka, intermittently
coexisting with oscillating Bleis Marscha cirque glacierets). The formation
phases appear to be controlled in the source area by the climate-sensitive
accumulation of an ice-debris mixture in proportions susceptible to rock
glacier creep. The ongoing cohesive movement of the older generations requires
ice at a depth which is possibly as old as its Early–Middle Holocene debris
mantle. Permafrost degradation is attenuated by “thermal filtering” of the
coarse debris boulder mantle and implies that the dynamics of the Bleis
Marscha lobes that once formed persisted over millennia are less sensitive
to climate. The cosmogenic radionuclide inventories of boulders on a moving
rock glacier ideally record time since deposition on the rock glacier root
but are stochastically altered by boulder instabilities and erosional
processes. This work contributes to deciphering the long-term development
and the past to quasi-present climate sensitivity of rock glaciers.</p> |
url |
https://tc.copernicus.org/articles/15/2057/2021/tc-15-2057-2021.pdf |
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