Influence of geomorphological setting, fluvial-, glaciofluvial- and mass-movement processes on sedimentation in alpine lakes
Lacustrine sediments are often used for paleoclimate reconstructions as continuous archives of several physical and biological proxies. The relation between autochthonous and allochthonous sedimentation in alpine lakes is a complex system that may cause difficulties when interpreting biological and...
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Online Access: | http://dx.doi.org/10.1177/0959683609104042 http://journals.sagepub.com/doi/pdf/10.1177/0959683609104042 |
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crsagepubl:10.1177/0959683609104042 2024-05-19T07:46:11+00:00 Influence of geomorphological setting, fluvial-, glaciofluvial- and mass-movement processes on sedimentation in alpine lakes Rubensdotter, Lena Rosqvist, Gunhild 2009 http://dx.doi.org/10.1177/0959683609104042 http://journals.sagepub.com/doi/pdf/10.1177/0959683609104042 en eng SAGE Publications http://journals.sagepub.com/page/policies/text-and-data-mining-license The Holocene volume 19, issue 4, page 665-678 ISSN 0959-6836 1477-0911 journal-article 2009 crsagepubl https://doi.org/10.1177/0959683609104042 2024-04-25T08:13:05Z Lacustrine sediments are often used for paleoclimate reconstructions as continuous archives of several physical and biological proxies. The relation between autochthonous and allochthonous sedimentation in alpine lakes is a complex system that may cause difficulties when interpreting biological and physical parameters. Results from previous studies of alpine lakes in northern Sweden have demonstrated that non-glacial processes produce minerogenic lake deposits with similar physical characteristics (density, LOI, magnetic susceptibility, grain-size) as those that have been associated with glacier fluctuations in proglacial lakes. In this study of two consecutive proglacial alpine lakes we show that fluvial redeposition of alluvial fan deposits significantly affects the Holocene lake sedimentation. Depending on the geomorphological setting, such fluvial redeposition signals may actually overprint a glaciofluvial signal. We also show that minerogenic laminations of fluvial origin are impossible to separate from the type of laminations usually used to infer glacier activity using the most common lithological sediment parameters. This emphasizes the complexity of sediment transport system in proglacial (paraglacial) settings where redeposition of older glacial sediment is of major importance. Our results highlight the need for thorough understanding of the geomorphological setting before inferences are made about climate variations from sedimentation in alpine lakes. Both lakes in this study contain sediment sequences with both episodic (turbidites) and continuously deposited sediments. Unfortunately we have too few radiocarbon dates to exactly date the turbidites but it is clear that turbidite layers in any case should be excluded from age model constructions since episodic sedimentation significantly influences the sediment age—depth relationship. In our age-model turbidites cause a potential dating error of several hundred, up to a thousand, years. Article in Journal/Newspaper Northern Sweden SAGE Publications The Holocene 19 4 665 678 |
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English |
description |
Lacustrine sediments are often used for paleoclimate reconstructions as continuous archives of several physical and biological proxies. The relation between autochthonous and allochthonous sedimentation in alpine lakes is a complex system that may cause difficulties when interpreting biological and physical parameters. Results from previous studies of alpine lakes in northern Sweden have demonstrated that non-glacial processes produce minerogenic lake deposits with similar physical characteristics (density, LOI, magnetic susceptibility, grain-size) as those that have been associated with glacier fluctuations in proglacial lakes. In this study of two consecutive proglacial alpine lakes we show that fluvial redeposition of alluvial fan deposits significantly affects the Holocene lake sedimentation. Depending on the geomorphological setting, such fluvial redeposition signals may actually overprint a glaciofluvial signal. We also show that minerogenic laminations of fluvial origin are impossible to separate from the type of laminations usually used to infer glacier activity using the most common lithological sediment parameters. This emphasizes the complexity of sediment transport system in proglacial (paraglacial) settings where redeposition of older glacial sediment is of major importance. Our results highlight the need for thorough understanding of the geomorphological setting before inferences are made about climate variations from sedimentation in alpine lakes. Both lakes in this study contain sediment sequences with both episodic (turbidites) and continuously deposited sediments. Unfortunately we have too few radiocarbon dates to exactly date the turbidites but it is clear that turbidite layers in any case should be excluded from age model constructions since episodic sedimentation significantly influences the sediment age—depth relationship. In our age-model turbidites cause a potential dating error of several hundred, up to a thousand, years. |
format |
Article in Journal/Newspaper |
author |
Rubensdotter, Lena Rosqvist, Gunhild |
spellingShingle |
Rubensdotter, Lena Rosqvist, Gunhild Influence of geomorphological setting, fluvial-, glaciofluvial- and mass-movement processes on sedimentation in alpine lakes |
author_facet |
Rubensdotter, Lena Rosqvist, Gunhild |
author_sort |
Rubensdotter, Lena |
title |
Influence of geomorphological setting, fluvial-, glaciofluvial- and mass-movement processes on sedimentation in alpine lakes |
title_short |
Influence of geomorphological setting, fluvial-, glaciofluvial- and mass-movement processes on sedimentation in alpine lakes |
title_full |
Influence of geomorphological setting, fluvial-, glaciofluvial- and mass-movement processes on sedimentation in alpine lakes |
title_fullStr |
Influence of geomorphological setting, fluvial-, glaciofluvial- and mass-movement processes on sedimentation in alpine lakes |
title_full_unstemmed |
Influence of geomorphological setting, fluvial-, glaciofluvial- and mass-movement processes on sedimentation in alpine lakes |
title_sort |
influence of geomorphological setting, fluvial-, glaciofluvial- and mass-movement processes on sedimentation in alpine lakes |
publisher |
SAGE Publications |
publishDate |
2009 |
url |
http://dx.doi.org/10.1177/0959683609104042 http://journals.sagepub.com/doi/pdf/10.1177/0959683609104042 |
genre |
Northern Sweden |
genre_facet |
Northern Sweden |
op_source |
The Holocene volume 19, issue 4, page 665-678 ISSN 0959-6836 1477-0911 |
op_rights |
http://journals.sagepub.com/page/policies/text-and-data-mining-license |
op_doi |
https://doi.org/10.1177/0959683609104042 |
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The Holocene |
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