Morphological response to Quaternary deformation at an intermontane basin piedmont, the northern Tien Shan, Kyrghyzstan

Dan Bowman, Andrey Korjenkov, Naomi Porat, Birka Czassny

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21 Scopus citations

Abstract

The Tien Shan is a most active intracontinental mountain-building range with abundant Quaternary fault-related folding. In order to improve our understanding of Quaternary intermontane basin deformation, we investigated the intermontane Issyk-Kul Lake area, an anticline that was up-warped through the piedmont cover, causing partitioning of the alluvial fan veneer. To follow the morphological scenario during the warping process, we relied on surface-exposed and trenched structures and on alluvial fans and bajadas as reference surfaces. We used air photos and satellite images to analyze the spatial-temporal morphological record and determined the age of near surface sediments by luminescence dating. We demonstrate that the up-warped Ak-Teke hills are a thrust-generated subdued anticline with strong morphological asymmetry which results from the coupling of the competing processes of up-warp and erosional feedback. The active creeks across the up-warped anticline indicate that the antecedent drainage system kept pace with the rate of uplift. The rivers which once sourced the piedmont, like the Toru-Aygyr, Kultor and the Dyuresu, became deeply entrenched and gradually transformed the study area into an abandoned morphological surface. The up-warp caused local lateral drainage diversion in front of the northern backlimb and triggered the formation of a dendritic drainage pattern upfan. Luminescence dating suggest that the period of up-warp and antecedent entrenchment started after 157 ka. The morphologically mature study area demonstrates the response of fluvial systems to growing folds on piedmont areas, induced by a propagating frontal fold at a thrust belt edge, following shortening.

Original languageEnglish
Pages (from-to)1-24
Number of pages24
JournalGeomorphology
Volume63
Issue number1-2
DOIs
StatePublished - 1 Nov 2004
Externally publishedYes

Funding

We thank Mr. P. Louppen and Mrs. R. Bluestein-Livnon of Ben-Gurion University as well as Mrs. B. Fabian of Potsdam University for the computer-drawn illustrations. This study was supported by INTAS—The International Association for the Promotion of Cooperation with Scientists from the Independent States of the former Soviet Union, grant no. 96-1923. We also acknowledge the support from ISTC for project no. KR-357. A.K. thanks the Deutscher Akadamischer Austauschdienst (DAAD), the Alexander von Humboldt Foundation, the United States Civilian Research and Development Foundation (CRDF) for grant YG2-2542-BI-03 and M. Strecker for supporting his stay in Germany.

FundersFunder number
INTAS
International Association for the Promotion of Cooperation96-1923
United States Civilian Research and Development Foundation
Alexander von Humboldt-Stiftung
Citrus Research and Development FoundationYG2-2542-BI-03
Deutscher Akademischer Austauschdienst
International Science and Technology CenterKR-357

    Keywords

    • Alluvial fans
    • Antecedent drainage
    • Issyk-Kul Lake
    • Thrust faulting
    • Tien Shan

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