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

Autor(en)

Konstanze Stübner, Bodo Bookhagen, Silke Merchel, Johannes Lachner, Mustafo Gadoev

Abstrakt

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 Be-10 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 km(3) 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 similar to 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. (C) 2021 Elsevier Ltd. All rights reserved.

Organisation(en)

Isotopenphysik

Externe Organisation(en)

Helmholtz-Zentrum Dresden-Rossendorf, Universität Potsdam, Academy of Sciences of the Republic of Tajikistan

Journal

Quaternary Science Reviews

Band

257

Anzahl der Seiten

15

ISSN

0277-3791

DOI

https://doi.org/10.1016/j.quascirev.2021.106857

Publikationsdatum

04-2021

Peer-reviewed

Ja

ÖFOS 2012

103014 Kernphysik, 105404 Geomorphologie

Schlagwörter

ASJC Scopus Sachgebiete

Global and Planetary Change, Ecology, Evolution, Behavior and Systematics, Archaeology, Archaeology, Geology

Link zum Portal

https://ucris.univie.ac.at/portal/de/publications/unravelling-the-pleistocene-glacial-history-of-the-pamir-mountains-central-asia(be5b4ab4-8e91-4572-8645-4ee4e790d4af).html