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Ice dams, outburst floods, and glacial incision at the western margin of the Tibetan Plateau: A >100 k.y. chronology from the Shyok Valley, Karakoram

Scherler, Dirk and Munack, Henry and Mey, Jürgen and Eugster, Patricia and Wittmann, Hella and Codilean, Alexandru T. and Kubik, Peter and Strecker, Manfred R. (2014) Ice dams, outburst floods, and glacial incision at the western margin of the Tibetan Plateau: A >100 k.y. chronology from the Shyok Valley, Karakoram. Geological Society of America Bulletin, 126 (5-6). pp. 738-758. ISSN 0016-7606. https://resolver.caltech.edu/CaltechAUTHORS:20140926-091238447

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Abstract

Some of the largest and most erosive floods on Earth result from the failure of glacial dams. While potentially cataclysmic ice dams are recognized to have repeatedly formed along ice-sheet margins, much less is known about the frequency and longevity of ice dams caused by mountain glaciers, and their impact on landscape evolution. Here we present field observations and results from cosmogenic nuclide dating that allow reconstructing a >100-k.y.-long history of glacial damming in the Shyok Valley, eastern Karakoram (South Asia). Our field observations provide evidence that Asia’s second-longest glacier, the Siachen, once extended for over 180 km and blocked the Shyok River during the penultimate glacial period, leading to upstream deposition of a more than 400-m-thick fluvio-lacustrine valley fill. ^(10)Be-depth profile modeling indicates that glacial damming ended with the onset of the Eemian interglacial and that the Shyok River subsequently incised the valley fill at an average rate of ∼4–7 m k.y.^(–1). Comparison with contemporary ice-dammed lakes in the Karakoram and elsewhere suggests recurring outburst floods during the aggradation period, while over 25 cycles of fining-upward lake deposits within the valley fill indicate impounding of floods from farther upstream. Despite prolonged damming, the net effect of this and probably earlier damming episodes by the Siachen Glacier is dominated by glacial erosion in excess of fluvial incision, as evidenced by a pronounced overdeepening that follows the glaciated valley reach. Strikingly similar overdeepened valleys at all major confluences of the Shyok and Indus Rivers with Karakoram tributaries indicate that glacial dams and subsequent outburst floods have been widespread and frequent in this region during the Quaternary. Our study suggests that the interaction of Karakoram glaciers with the Shyok and Indus Rivers promoted valley incision and headward erosion into the western margin of the Tibetan Plateau.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1130/B30942.1 DOIArticle
http://gsabulletin.gsapubs.org/content/126/5-6/738PublisherArticle
http://bulletin.geoscienceworld.org/content/126/5-6/738.abstractPublisherArticle
Additional Information:© 2014 Geological Society of America. Received 12 June 2013. Revision received 5 November 2013. Accepted 12 December 2013. First published online February 13, 2014. This research was funded by the German Federal Ministry of Education and Research (BMBF, PROGRESS). D.S. was supported by the Alexander von Humboldt Foundation. H.M. was supported by DFG grant KO3937/2. P.E. was supported by DFG graduate school GK1364 (DFG grant STR373/21-2). We thank R. Thiede and T. Tsering Lonpo for support during fieldwork, S. Mischke for analyzing the fossil content of our lake samples, J. Bloethe for testing OSL dating on the lake sediments, T. Schildgen, D. Montgomery, J. Dortch, and D. Egholm for valuable comments on an earlier draft, B. Hallet for stimulating discussions, and D. Burbank for a constructive review that helped improve the manuscript.
Funders:
Funding AgencyGrant Number
German Federal Ministry of Education and Research (BMBF)UNSPECIFIED
Alexander von Humboldt FoundationUNSPECIFIED
Deutsche Forschungsgemeinschaft (DFG)KO3937/2
Deutsche Forschungsgemeinschaft (DFG)GK1364
Deutsche Forschungsgemeinschaft (DFG)STR373/21-2
Issue or Number:5-6
Record Number:CaltechAUTHORS:20140926-091238447
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20140926-091238447
Official Citation:Dirk Scherler, Henry Munack, Jürgen Mey, Patricia Eugster, Hella Wittmann, Alexandru T. Codilean, Peter Kubik, and Manfred R. Strecker Ice dams, outburst floods, and glacial incision at the western margin of the Tibetan Plateau: A >100 k.y. chronology from the Shyok Valley, Karakoram Geological Society of America Bulletin, May 2014, v. 126, no. 5-6, p. 738-758, first published on February 13, 2014, doi:10.1130/B30942.1
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:50055
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:09 Oct 2014 22:47
Last Modified:03 Oct 2019 07:19

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