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

Research output: Contribution to journalArticleResearchpeer review

Authors

  • Kevin Ratnayaka
  • Ralf Hetzel
  • Jens Hornung
  • Andrea Hampel
  • Matthias Hinderer
  • Manfred Frechen

External Research Organisations

  • University of Münster
  • Technische Universität Darmstadt
  • Leibniz Institute for Applied Geophysics (LIAG)
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Details

Original languageEnglish
Pages (from-to)431-449
Number of pages19
JournalQuaternary Research (United States)
Volume91
Issue number1
Early online date18 Dec 2018
Publication statusPublished - 1 Jan 2019

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.

Keywords

    Be exposure dating, C dating, Alluvial fan, Andes, Climate history, Peru, Sedimentation rate

ASJC Scopus subject areas

Sustainable Development Goals

Cite this

Postglacial alluvial fan dynamics in the Cordillera Oriental, Peru, and palaeoclimatic implications. / Ratnayaka, Kevin; Hetzel, Ralf; Hornung, Jens et al.
In: Quaternary Research (United States), Vol. 91, No. 1, 01.01.2019, p. 431-449.

Research output: Contribution to journalArticleResearchpeer review

Ratnayaka K, Hetzel R, Hornung J, Hampel A, Hinderer M, Frechen M. Postglacial alluvial fan dynamics in the Cordillera Oriental, Peru, and palaeoclimatic implications. Quaternary Research (United States). 2019 Jan 1;91(1):431-449. Epub 2018 Dec 18. doi: 10.1017/qua.2018.106
Ratnayaka, Kevin ; Hetzel, Ralf ; Hornung, Jens et al. / Postglacial alluvial fan dynamics in the Cordillera Oriental, Peru, and palaeoclimatic implications. In: Quaternary Research (United States). 2019 ; Vol. 91, No. 1. pp. 431-449.
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