Quaternary Geochronology OSL dating of fluvial and lacustrine sediment in Ranwu Lake, Southeastern Tibet

Wu, Y.; Chen, Y.; Huang, L.; Ding, P.; Zhang, J.; Demidov, N.E.; Isaev, V.S.; Sadokov, D.O.; Wei, G.

Авторы: Wu Yang, Chen Yiwei, Huang Long, Ding Ping, Zhang Jifeng, Demidov N.E., Isaev V.S., Sadokov D.O., Wei Gangjian
Журнал: Quaternary Geochronology
Год издания: 2024
Издательство: Elsevier BV
Местоположение издательства: Netherlands
Первая страница: 3
Последняя страница: 36
Аннотация: The Tibetan Plateau (TP) and its surrounding regions is the largest global store offrozen water after the Arctic and Antarctic. As glaciers recede and lakes expand inresponse to the significant warming on the TP, accelerated transition from ice andsnow into liquid water has caused imbalance in the Asian water tower. Record ofglacier change and its melting history is important for future assessment. With thenumber and size of glacial lakes increase rapidly, more Glacial Lake Outburst Floods(GLOFs) occur in the Himalayas, aggravating risks to downstream regions. To betterunderstand this process, it is necessary to evaluate the evolutionary history of largeglacial lakes on the TP. Progalcial lakes in southeastern TP are rarely studied, despitethat glaciers in this region experienced the most intensive recession and shrinkage.In this study, we investigated the Ranwu proglacial lake in the southeastern edgeof the TP, at the north slope of the Himalayas. Given the abundance of glacialmoraines in this region, we found a high platform-like topography (P1) composed ofthick lacustrine silts (>8 m), suggesting that a high lake once existed. A series of well38 sorted near-shore sands on slopes flanking modern lake (S1-S6) were also used as anconservative indicator of past lake level. Based on OSL dating of 15 fluvial/lacustrine samples from 7 profiles, using both quartz OSL and K-feldspar pIRIR signals,fluctuation history of the Ranwu Lake was investigated. Our results suggest that: 1) OSL signals from some coarse-grained quartz exhibitapparent anomalous fading, while the IR50°C signals from coarse-grained K-feldsparfor most samples show a low/negligible degree of fading. Corrected quartz agesgenerally correlate well with IR50 ages, while pIRIR225°C signals show partialbleaching; 2) The recent highest lake-level for Ranwu Lake should exceed 4,390 m(+464 m above modern lake), with a coverage of ~324 km2 Five fine-grained samples near the top of P1 suggest an age estimation for the lake period of about 49-55 ka; 3) A very low lake level (~10 m) occurred around 30 ka, followed by a gradual rising toabout +350 m from 30 ka to 14.5 ka, possibly linked to the formation of a dammedlake associated with glacier advance during the LGM; 4) since 14.5 ka, no relevantsediment were found from slopes near the modern lake. We deduce that a rapid drainof the dammed lake occurred after the dam breach. Our results provide new evidenceto understand the evolution of Ranwu Lake and the complex interactions betweenglacier dynamics and lake level change
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Quaternary Geochronology OSL dating of fluvial and lacustrine sediment in Ranwu Lake, Southeastern Tibetстатья

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