New evidence for active talus-foot rock glaciers at Øyberget, southern Norway, and their development during the Holocene
Synthetic aperture radar interferometry (InSAR) measurements demonstrate that lobate, blocky depositional landforms, located in southern Norway at an altitude of ~530 m above sea level, with an estimated mean annual air temperature of ~1.6°C, currently exhibit deformation attributed to viscous creep...
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crsagepubl:10.1177/09596836211033226 2024-05-19T07:40:47+00:00 New evidence for active talus-foot rock glaciers at Øyberget, southern Norway, and their development during the Holocene Nesje, Atle Matthews, John A Linge, Henriette Bredal, Marie Wilson, Peter Winkler, Stefan 2021 http://dx.doi.org/10.1177/09596836211033226 http://journals.sagepub.com/doi/pdf/10.1177/09596836211033226 http://journals.sagepub.com/doi/full-xml/10.1177/09596836211033226 en eng SAGE Publications http://journals.sagepub.com/page/policies/text-and-data-mining-license The Holocene volume 31, issue 11-12, page 1786-1796 ISSN 0959-6836 1477-0911 journal-article 2021 crsagepubl https://doi.org/10.1177/09596836211033226 2024-04-25T08:12:14Z Synthetic aperture radar interferometry (InSAR) measurements demonstrate that lobate, blocky depositional landforms, located in southern Norway at an altitude of ~530 m above sea level, with an estimated mean annual air temperature of ~1.6°C, currently exhibit deformation attributed to viscous creep. Five years of InSAR measurements for six lobes demonstrate average surface velocities of 1.2–22.0 mm/year with maximum rates of 17.5–55.6 mm/year. New Schmidt-hammer exposure-age dating (SHD) of two proximal lobes reveals mid-Holocene ages (7.6 ± 1.3 ka and 6.0 ± 1.2 ka), which contrast with the early-Holocene SHD and 10 Be ages obtained previously from distal lobes, and late-Holocene SHD ages presented here from two adjacent talus slopes (2.3 ± 1.0 ka and 2.4 ± 1.0 ka). Although passive transport of boulders on the surfaces of these small, slow-moving rock glaciers affected by compressive flow means that the exposure ages are close to minimum estimates of the time elapsed since lobe inception, disturbance of boulders on rock glaciers is a source of potentially serious underestimates of rock-glacier age. Rock-glacier development at Øyberget began shortly after local deglaciation around 10 ka before present and continued throughout the Holocene in response to microclimatic undercooling within the coarse blocky surface layer of the talus and rock-glacier lobes. We suggest this enhanced cooling lowers mean annual surface-layer temperature by at least ~3.6°C, which is needed at such a low altitude to sustain sporadic permafrost and avoid fast thawing as atmospheric temperatures rise. Our results point to circumstances where inferences about rock glaciers as indicators of regional climate should be interpreted with caution, and where they may be less useful in palaeoclimatic reconstruction than previously thought. Article in Journal/Newspaper glacier permafrost SAGE Publications The Holocene 095968362110332 |
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English |
description |
Synthetic aperture radar interferometry (InSAR) measurements demonstrate that lobate, blocky depositional landforms, located in southern Norway at an altitude of ~530 m above sea level, with an estimated mean annual air temperature of ~1.6°C, currently exhibit deformation attributed to viscous creep. Five years of InSAR measurements for six lobes demonstrate average surface velocities of 1.2–22.0 mm/year with maximum rates of 17.5–55.6 mm/year. New Schmidt-hammer exposure-age dating (SHD) of two proximal lobes reveals mid-Holocene ages (7.6 ± 1.3 ka and 6.0 ± 1.2 ka), which contrast with the early-Holocene SHD and 10 Be ages obtained previously from distal lobes, and late-Holocene SHD ages presented here from two adjacent talus slopes (2.3 ± 1.0 ka and 2.4 ± 1.0 ka). Although passive transport of boulders on the surfaces of these small, slow-moving rock glaciers affected by compressive flow means that the exposure ages are close to minimum estimates of the time elapsed since lobe inception, disturbance of boulders on rock glaciers is a source of potentially serious underestimates of rock-glacier age. Rock-glacier development at Øyberget began shortly after local deglaciation around 10 ka before present and continued throughout the Holocene in response to microclimatic undercooling within the coarse blocky surface layer of the talus and rock-glacier lobes. We suggest this enhanced cooling lowers mean annual surface-layer temperature by at least ~3.6°C, which is needed at such a low altitude to sustain sporadic permafrost and avoid fast thawing as atmospheric temperatures rise. Our results point to circumstances where inferences about rock glaciers as indicators of regional climate should be interpreted with caution, and where they may be less useful in palaeoclimatic reconstruction than previously thought. |
format |
Article in Journal/Newspaper |
author |
Nesje, Atle Matthews, John A Linge, Henriette Bredal, Marie Wilson, Peter Winkler, Stefan |
spellingShingle |
Nesje, Atle Matthews, John A Linge, Henriette Bredal, Marie Wilson, Peter Winkler, Stefan New evidence for active talus-foot rock glaciers at Øyberget, southern Norway, and their development during the Holocene |
author_facet |
Nesje, Atle Matthews, John A Linge, Henriette Bredal, Marie Wilson, Peter Winkler, Stefan |
author_sort |
Nesje, Atle |
title |
New evidence for active talus-foot rock glaciers at Øyberget, southern Norway, and their development during the Holocene |
title_short |
New evidence for active talus-foot rock glaciers at Øyberget, southern Norway, and their development during the Holocene |
title_full |
New evidence for active talus-foot rock glaciers at Øyberget, southern Norway, and their development during the Holocene |
title_fullStr |
New evidence for active talus-foot rock glaciers at Øyberget, southern Norway, and their development during the Holocene |
title_full_unstemmed |
New evidence for active talus-foot rock glaciers at Øyberget, southern Norway, and their development during the Holocene |
title_sort |
new evidence for active talus-foot rock glaciers at øyberget, southern norway, and their development during the holocene |
publisher |
SAGE Publications |
publishDate |
2021 |
url |
http://dx.doi.org/10.1177/09596836211033226 http://journals.sagepub.com/doi/pdf/10.1177/09596836211033226 http://journals.sagepub.com/doi/full-xml/10.1177/09596836211033226 |
genre |
glacier permafrost |
genre_facet |
glacier permafrost |
op_source |
The Holocene volume 31, issue 11-12, page 1786-1796 ISSN 0959-6836 1477-0911 |
op_rights |
http://journals.sagepub.com/page/policies/text-and-data-mining-license |
op_doi |
https://doi.org/10.1177/09596836211033226 |
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The Holocene |
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1799480354061418496 |