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Glacial advances constrained by 10Be exposure dating of bedrock landslides, Kyrgyz Tien Shan

Journal Article


Abstract


  • Numerous large landslide deposits occur in the Tien Shan, a tectonically active intraplate orogen in Central

    Asia. Yet their significance in Quaternary landscape evolution and natural hazard assessment remains

    unresolved due to the lack of "absolute" age constraints. Here we present the first 10Be exposure ages for three

    prominent (N107 m3

    ) bedrock landslides that blocked major rivers and formed lakes, two of which

    subsequently breached, in the northern Kyrgyz Tien Shan. Three 10Be ages reveal that one landslide in the

    Alamyedin River occurred at 11–15 ka, which is consistent with two 14C ages of gastropod shells from

    reworked loess capping the landslide. One large landslide in Aksu River is among the oldest documented in

    semi-arid continental interiors, with a 10Be age of 63–67 ka. The Ukok River landslide deposit(s) yielded

    variable 10Be ages, which may result from multiple landslides, and inheritance of 10Be. Two 10Be ages of 8.2

    and 5.9 ka suggest that one major landslide occurred in the early to mid-Holocene, followed by at least one

    other event between 1.5 and 0.4 ka. Judging from the regional glacial chronology, all three landslides have

    occurred between major regional glacial advances. Whereas Alamyedin and Ukok can be considered as

    postglacial in this context, Aksu is of interglacial age. None of the landslide deposits show traces of glacial

    erosion, hence their locations and 10Be ages mark maximum extents and minimum ages of glacial advances,

    respectively. Using toe-to-headwall altitude ratios of 0.4–0.5, we reconstruct minimum equilibrium-line

    altitudes that exceed previous estimates by as much as 400 m along the moister northern fringe of the Tien

    Shan. Our data show that deposits from large landslides can provide valuable spatio-temporal constraints for

    glacial advances in landscapes where moraines and glacial deposits have low preservation potential.

Authors


  •   Sanhueza-Pino, Katia (external author)
  •   Korup, Oliver (external author)
  •   Hetzel, Ralf (external author)
  •   Munack, Henry
  •   Weidinger, Johannes T. (external author)
  •   Dunning, Stuart (external author)
  •   Ormukov, Cholponbek (external author)
  •   Kubik, Peter W. (external author)

Publication Date


  • 2011

Citation


  • Sanhueza-Pino, K., Korup, O., Hetzel, R., Munack, H., Weidinger, J. T., Dunning, S., Ormukov, C. & Kubik, P. W. (2011). Glacial advances constrained by 10Be exposure dating of bedrock landslides, Kyrgyz Tien Shan. Quaternary Research, 76 (3), 295-304.

Scopus Eid


  • 2-s2.0-82455164278

Has Global Citation Frequency


Number Of Pages


  • 9

Start Page


  • 295

End Page


  • 304

Volume


  • 76

Issue


  • 3

Place Of Publication


  • United States

Abstract


  • Numerous large landslide deposits occur in the Tien Shan, a tectonically active intraplate orogen in Central

    Asia. Yet their significance in Quaternary landscape evolution and natural hazard assessment remains

    unresolved due to the lack of "absolute" age constraints. Here we present the first 10Be exposure ages for three

    prominent (N107 m3

    ) bedrock landslides that blocked major rivers and formed lakes, two of which

    subsequently breached, in the northern Kyrgyz Tien Shan. Three 10Be ages reveal that one landslide in the

    Alamyedin River occurred at 11–15 ka, which is consistent with two 14C ages of gastropod shells from

    reworked loess capping the landslide. One large landslide in Aksu River is among the oldest documented in

    semi-arid continental interiors, with a 10Be age of 63–67 ka. The Ukok River landslide deposit(s) yielded

    variable 10Be ages, which may result from multiple landslides, and inheritance of 10Be. Two 10Be ages of 8.2

    and 5.9 ka suggest that one major landslide occurred in the early to mid-Holocene, followed by at least one

    other event between 1.5 and 0.4 ka. Judging from the regional glacial chronology, all three landslides have

    occurred between major regional glacial advances. Whereas Alamyedin and Ukok can be considered as

    postglacial in this context, Aksu is of interglacial age. None of the landslide deposits show traces of glacial

    erosion, hence their locations and 10Be ages mark maximum extents and minimum ages of glacial advances,

    respectively. Using toe-to-headwall altitude ratios of 0.4–0.5, we reconstruct minimum equilibrium-line

    altitudes that exceed previous estimates by as much as 400 m along the moister northern fringe of the Tien

    Shan. Our data show that deposits from large landslides can provide valuable spatio-temporal constraints for

    glacial advances in landscapes where moraines and glacial deposits have low preservation potential.

Authors


  •   Sanhueza-Pino, Katia (external author)
  •   Korup, Oliver (external author)
  •   Hetzel, Ralf (external author)
  •   Munack, Henry
  •   Weidinger, Johannes T. (external author)
  •   Dunning, Stuart (external author)
  •   Ormukov, Cholponbek (external author)
  •   Kubik, Peter W. (external author)

Publication Date


  • 2011

Citation


  • Sanhueza-Pino, K., Korup, O., Hetzel, R., Munack, H., Weidinger, J. T., Dunning, S., Ormukov, C. & Kubik, P. W. (2011). Glacial advances constrained by 10Be exposure dating of bedrock landslides, Kyrgyz Tien Shan. Quaternary Research, 76 (3), 295-304.

Scopus Eid


  • 2-s2.0-82455164278

Has Global Citation Frequency


Number Of Pages


  • 9

Start Page


  • 295

End Page


  • 304

Volume


  • 76

Issue


  • 3

Place Of Publication


  • United States