TY  - JOUR
A1  - Sanhueza-Pino, Katia
A1  - Korup, Oliver
A1  - Hetzel, Ralf
A1  - Munack, Henry
A1  - Weidinger, Johannes T.
A1  - Dunning, Stuart A.
A1  - Ormukov, Cholponbek
A1  - Kubik, Peter W.
T1  - Glacial advances constrained by Be-10 exposure dating of bedrock landslides, Kyrgyz Tien Shan
JF  - Quaternary research : an interdisciplinary journal
N2  - 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 Be-10 exposure ages for three prominent (>10(7) m(3)) bedrock landslides that blocked major rivers and formed lakes, two of which subsequently breached, in the northern Kyrgyz Tien Shan. Three Be-10 ages reveal that one landslide in the Alamyedin River occurred at 11-15 ka, which is consistent with two C-14 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 Be-10 age of 63-67 ka. The Ukok River landslide deposit(s) yielded variable Be-10 ages, which may result from multiple landslides, and inheritance of Be-10. Two Be-10 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 I Be 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. (C) 2011 University of Washington. Published by Elsevier Inc. All rights reserved.
KW  - Landslide
KW  - Rock avalanche
KW  - Be-10 exposure dating
KW  - Quaternary glaciations
KW  - Tien Shan
Y1  - 2011
U6  - https://doi.org/10.1016/j.yqres.2011.06.013
SN  - 0033-5894
VL  - 76
IS  - 3
SP  - 295
EP  - 304
PB  - Elsevier
CY  - San Diego
ER  -