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Lag and mixing during sediment transfer across the Tian Shan piedmont caused by climate-driven aggradation-incision cycles

Malatesta, Luca C. and Avouac, Jean-Philippe and Brown, Nathan D. and Breitenbach, Sebastian F. M. and Pan, Jiawei and Chevalier, Marie-Luce and Rhodes, Edward and Saint-Carlier, Dimitri and Zhang, Wenjing and Charreau, Julien and Lavé, Jérôme and Blard, Pierre-Henri (2018) Lag and mixing during sediment transfer across the Tian Shan piedmont caused by climate-driven aggradation-incision cycles. Basin Research, 30 (4). pp. 613-635. ISSN 0950-091X. https://resolver.caltech.edu/CaltechAUTHORS:20171017-110101413

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Abstract

Transient sediment storage and mixing of deposits of various ages during transport across alluvial piedmonts alters the clastic sedimentary record. We quantify buffering and mixing during cycles of aggradation-incision in the north piedmont of the Eastern Tian Shan. We complement existing chronologic data with 20 new luminescence ages and one cosmogenic radionuclide age of terrace abandonment and alluvial aggradation. Over the last 0.5 Myrs, the piedmont deeply incised and aggraded many times per 100 kyr. Aggradation is driven by an increased flux of glacial sediment accumulated in the high range and flushed onto the piedmont by greater water discharge at stadial-interstadial transitions. After this sediment is evacuated from the high range, the reduced input sediment flux results in fluvial incision of the piedmont as fast as 9 cm/yr and to depths up to 330 m. The timing of incision onset is different in each river and does not directly reflect climate forcing but the necessary time for the evacuation of glacial sediment from the high range. A significant fraction of sediments evacuated from the high range is temporarily stored on the piedmont before a later incision phase delivers it to the basin. Coarse sediments arrive in the basin with a lag of at least 7 to 14 kyrs between the first evacuation from the mountain and later basinward transport. The modern output flux of coarse sediments from the piedmont contains a significant amount of recycled material that was deposited on the piedmont as early as the Middle Pleistocene. Variations in temperature and moisture delivered by the Westerlies are the likely cause of repeated aggradation-incision cycles in the north piedmont instead of monsoonal precipitation. The arrival of the gravel front into the proximal basin is delayed relative to the fine-grained load and both are separated by a hiatus. This work shows, based on field observations and data, how sedimentary systems respond to climatic perturbations, and how sediment recycling and mixing can ensue.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1111/bre.12267DOIArticle
http://onlinelibrary.wiley.com/doi/10.1111/bre.12267/abstractPublisherArticle
ORCID:
AuthorORCID
Avouac, Jean-Philippe0000-0002-3060-8442
Additional Information:© 2017 The Authors. Basin Research © 2017 John Wiley & Sons Ltd, European Association of Geoscientists & Engineers and International Association of Sedimentologists. Issue Online: 04 July 2018; Version of Record online: 31 October 2017; Accepted manuscript online: 12 October 2017; Manuscript accepted: 06 October 2017; Manuscript revised: 27 September 2017; Manuscript received: 14 March 2017. The authors thank Sébastien Castelltort for his sedimentological insights. Stimulating discussions with Laure Guérit were most useful to design our work. Jess Adkins provided precious advice regarding the climatic considerations. We thank Stéphane Dominguez for his help collecting the sample TS12-ANJ-T1B. Two anonymous reviewers provided important inputs to improve the original manuscript. This study was supported by a PRF New Direction grant of the American Chemical Society (grant number: PRF #53814-ND8) and a Doc.Mobility fellowship of the Swiss National Foundation (project number: P1SKP2_158716) for L. C. Malatesta. This study received funding from the European Union's Horizon 2020 Research and Innovation program under the Marie Sklodowska-Curie grant agreement No 691037 to S.F.M. Breitenbach.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
American Chemical Society Petroleum Research Fund53814-ND8
Swiss National Science Foundation (SNSF)P1SKP2_158716
Marie Curie Fellowship691037
Issue or Number:4
Record Number:CaltechAUTHORS:20171017-110101413
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20171017-110101413
Official Citation:Malatesta, L. C., Avouac, J. , Brown, N. D., Breitenbach, S. F., Pan, J. , Chevalier, M. , Rhodes, E. , Saint‐Carlier, D. , Zhang, W. , Charreau, J. , Lavé, J. and Blard, P. (2018), Lag and mixing during sediment transfer across the Tian Shan piedmont caused by climate‐driven aggradation–incision cycles. Basin Res, 30: 613-635. doi:10.1111/bre.12267
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:82415
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:17 Oct 2017 20:24
Last Modified:03 Oct 2019 18:54

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