Glacial advances constrained by$ ^{10}$Be exposure dating of bedrock landslides, Kyrgyz Tien Shan

Content Provider	Scilit
Author	Sanhueza-Pino, Katia Korup, Oliver Hetzel, Ralf Munack, Henry Weidinger, Johannes T. Dunning, Stuart Ormukov, Cholponbek Kubik, Peter W.
Copyright Year	2011
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$ ^{10}$Be 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$ ^{10}$Be ages reveal that one landslide in the Alamyedin River occurred at 11–15 ka, which is consistent with two$ ^{14}$C ages of gastropod shells from reworked loess capping the landslide. One large landslide in Aksu River is among the oldest documented in semi-arid continental interiors, with a$ ^{10}$Be age of 63–67 ka. The Ukok River landslide deposit(s) yielded variable$ ^{10}$Be ages, which may result from multiple landslides, and inheritance of$ ^{10}$Be. Two$ ^{10}$Be ages of 8.2 and 5.9 ka suggest that one major landslide occurred in the early to mid-Holocene, followed by at least one other event between 1.5 and 0.4 ka. Judging from the regional glacial chronology, all three landslides have occurred between major regional glacial advances. Whereas Alamyedin and Ukok can be considered as postglacial in this context, Aksu is of interglacial age. None of the landslide deposits show traces of glacial erosion, hence their locations and$ ^{10}$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.
Related Links	https://www.cambridge.org/core/services/aop-cambridge-core/content/view/A073B7FED7BBC0614282F35B4BA1D9B6/S0033589400007894a.pdf/div-class-title-glacial-advances-constrained-by-span-class-sup-10-span-be-exposure-dating-of-bedrock-landslides-kyrgyz-tien-shan-div.pdf
Ending Page	304
Page Count	10
Starting Page	295
ISSN	00335894
e-ISSN	10960287
DOI	10.1016/j.yqres.2011.06.013
Journal	Quaternary Research
Issue Number	3
Volume Number	76
Language	English
Publisher	Cambridge University Press (CUP)
Publisher Date	2011-11-01
Access Restriction	Open
Subject Keyword	Quaternary Research Physical Geography Natural Hazard Absolute Age
Content Type	Text
Resource Type	Article
Subject	Earth-Surface Processes Arts and Humanities