Publications

Unravelling the Pleistocene glacial history of the Pamir mountains, Central Asia

Author(s)
Konstanze Stübner, Bodo Bookhagen, Silke Merchel, Johannes Lachner, Mustafo Gadoev
Abstract

Several hundred thousand year old moraines preserved in the semi-arid environment of High Mountain Asia attest to Middle Pleistocene glaciations, but the regional correlation of glacial stages and the spatial extent of the glacial advances remain poorly constrained. We examined glacial landforms and Quaternary sediments in the Bartang valley, northwestern Pamir, a region with no previous quantitative glacial chronology. Using cosmogenic 10Be exposure ages, we dated glacially polished bedrock, moraines, and mass wasting deposits. Our data show that the northwestern Pamir was heavily glaciated in the Middle Pleistocene (≥220 ky) with large valley glaciers occupying some of the major valleys in the western Pamir. During the penultimate glacial cycle (191–130 ky) these valleys may have been largely ice free. Catastrophic mega debris flows with volumes ≥0.05 km3 occurred after the ice retreat and reflect paraglacial destabilization of glacial sediments. The age of the best-dated mega debris flow (81 ± 4 ky) is similar to moraine ages ∼70–80 ky documented throughout the Pamir, demonstrating that remobilized sediments may provide valuable age constraints on glacial histories. In order to facilitate regional comparison of glacial chronologies, we developed a Gaussian separation algorithm, which determines a moraine age from a distribution of boulder exposure ages based on the assumption that post-depositional processes prevail over inheritance, and that the oldest boulder ages best represent the timing of moraine formation. We compiled moraine boulder exposure ages from the Pamir and adjacent regions and provide a summary of Middle and early Late Pleistocene glacial cycles of western High-Mountain Asia.

Organisation(s)
Isotope Physics
External organisation(s)
Forschungszentrum Dresden Rossendorf (FZD), Universität Potsdam, National Academy of Sciences
Journal
Quaternary Science Reviews
Volume
257
No. of pages
15
ISSN
0277-3791
DOI
https://doi.org/10.1016/j.quascirev.2021.106857
Publication date
04-2021
Peer reviewed
Yes
Austrian Fields of Science 2012
103014 Nuclear physics, 105404 Geomorphology
Keywords
ASJC Scopus subject areas
Global and Planetary Change, Ecology, Evolution, Behavior and Systematics, Archaeology, Archaeology, Geology
Portal url
https://ucris.univie.ac.at/portal/en/publications/unravelling-the-pleistocene-glacial-history-of-the-pamir-mountains-central-asia(be5b4ab4-8e91-4572-8645-4ee4e790d4af).html