Postglacial alluvial fan dynamics in the Cordillera Oriental, Peru, and palaeoclimatic implications

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Ratnayaka, K.; Hetzel, R.; Hornung, J.; Hampel, A.; Hinderer, M.; Frechen, M.: Postglacial alluvial fan dynamics in the Cordillera Oriental, Peru, and palaeoclimatic implications. In: Quaternary Research 91 (2019), Nr. 1, S. 431-449. DOI: https://doi.org/10.1017/qua.2018.106

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Abstract: 
Alluvial fans record climate-driven erosion and sediment-transport processes and allow reconstructing past environmental conditions. Here we investigate the sedimentation history of two alluvial fans located in formerly glaciated valleys of the Cordillera Oriental, Peru. 10Be exposure ages from the fan surfaces and radiocarbon ages from the fan interiors constrain the final stages of fan formation. The 10Be and 14C ages cluster mainly between 13.3–9.3 ka and 11,500–9700 cal yr BP, respectively. Our age data set indicates that—after deglaciation—large amounts of fan sediment were deposited until ∼10 ka, when sedimentation rates declined rather abruptly. This pattern is supported by 10Be erosion rates for the fan catchments, because under the assumption of constant erosion the time needed to erode the material stored in the fans significantly exceeds their age. Correlating our ages with regional climate records indicates that precipitation exerts the primary control on fan sedimentation. Two periods with elevated lake levels and increased precipitation between 18 and 14.5 ka and from 13 to 11.5 ka resulted in rapid deposition of large fan lobes. Subsequently, lower precipitation rates decreased erosion in the catchments and sediment delivery to the fans, which have remained largely inactive since ∼9.5 ka.
License of this version: Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden. Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
Document Type: Article
Publishing status: publishedVersion
Issue Date: 2019
Appears in Collections:Naturwissenschaftliche Fakultät

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pos. country downloads
total perc.
1 image of flag of Germany Germany 8 29.63%
2 image of flag of United States United States 6 22.22%
3 image of flag of Peru Peru 3 11.11%
4 image of flag of Korea, Republic of Korea, Republic of 3 11.11%
5 image of flag of Indonesia Indonesia 2 7.41%
6 image of flag of China China 2 7.41%
7 image of flag of Netherlands Netherlands 1 3.70%
8 image of flag of India India 1 3.70%
9 image of flag of France France 1 3.70%

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