Timing of late Quaternary glaciations south of Mount Everest in the Khumbu Himal, Nepal

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Glacial geological evidence from throughout the Himalayan-Tibetan orogen is examined to determine the timing and extent of late Quaternary glaciation in this region and its relation to similar changes on a global scale. The evidence summarised here supports the existence of expanded ice caps and extensive valley glacier systems throughout the region during the late Quaternary. However, it cannot yet be determined whether the timing of the extent of maximum glaciation was synchronous throughout the entire region or whether the response was more varied. The lack of organic material needed for radiocarbon dating has hindered past progress in glacial reconstruction; however, application of optically stimulated luminescence and terrestrial cosmogenic radionuclide methods has recently expanded the number of chronologies throughout the region. Limits to the precision and accuracy available with these methods and, more importantly, geological uncertainty imposed by processes of moraine formation and alteration both conspire to limit the time resolution on which correlations can be made to Milankovitch timescales (several ka). In order to put all studies on a common scale, well-dated sites have been re-evaluated and all the published terrestrial cosmogenic nuclide ages for moraine boulders and glacially eroded surfaces in the Himalayan-Tibetan orogen have been recalculated. Locally detailed studies indicate that there are considerable variations in the extent of glaciation from one region to the next during a glaciation. Glaciers throughout monsoon-influenced Tibet, the Himalaya and the Transhimalaya are likely synchronous both with climate change resulting from oscillations in the South Asian monsoon and with Northern Hemisphere cooling cycles. In contrast, glaciers in Pamir in the far western regions of the Himalayan-Tibet orogen advanced asynchronously relative to the other regions that are monsooninfluenced regions and appear to be mainly in phase with the Northern Hemisphere cooling cycles. Broad patterns of local and regional variability based on equilibrium-line altitudes have yet to be fully assessed, but have the potential to help define changes in climatic gradients over time.

Section: Discussionmentioning

confidence: 99%

Section: Key Areasmentioning

confidence: 99%

Section: Key Areasmentioning

confidence: 99%

“…The chronology and dating of Finkel et al (2003) and Richards et al (2000b) are plotted on Fig. 11 together with probability plots for the recalculated TCN ages.…”

Section: Key Areasmentioning

confidence: 99%

Section: Timing Of Glaciationmentioning

confidence: 99%

See 3 more Smart Citations

Quaternary glaciation of the Himalayan–Tibetan orogen

Owen

Caffee

Finkel

et al. 2008

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210

143

Review of Holocene glacial chronologies based on radiocarbon dating in Tibet and its surrounding mountains

Chen

Yang

et al. 2008

A compilation of 53 14 C ages on moraines constrains the Holocene glacial history of Tibet and the surrounding mountains. Several Holocene glacial stages are identified. The Little Ice Age had three substages at 1.0-0.13 cal. ka BP. However, the glacial advances may have occurred 200-600 a earlier in southern and eastern bordering mountains than in the northern bordering mountains. The earlier glacial advance might have been driven by humid conditions in bordering areas of Tibet. Most glacial advances in the Neoglaciation occurred at 3.5-1.4 cal. ka BP. They can be identified in almost every mountain range. An early Holocene glacial advance occurred 9.4-8.8 cal. ka BP, in both central Tibet and bordering mountains. The timings of Holocene glacial advances are synchronous with the cooling periods in the d 18 O record from ice cores and with the results of optically stimulated luminescence dating and cosmogenic exposure dating in Tibet.

Timing and style of Late Pleistocene glaciation in the Queer Shan, northern Hengduan Mountains in the eastern Tibetan Plateau

Lai

et al. 2010

Glacial landforms and sediments provide evidence for the existence of two Late Pleistocene major glacial advances in the Queer Shan, northern Hengduan Mountains in the eastern Tibetan Plateau. In the current study, optically stimulated luminescence and electron spin resonance dating results reveal that the two glacial advances occurred during Marine Isotope Stage (MIS) 3 and the Last Glacial Maximum (LGM) in MIS 2, respectively. Geomorphic evidence shows that the glacial advance during MIS 3 was more extensive than that in MIS 2. This glacial advance is synchronous with other glaciated areas in the Himalaya and Tibet, but contrasts with global ice volumes that reached their maximum extent during the LGM. Glaciers in the Queer Shan are of the summer accumulation type and are mainly fed by precipitation from the south Asian monsoon. Palaeoclimate proxies show that during MIS 3 the south Asian monsoon strengthened and extended further north into the Tibetan Plateau to supply more precipitation as snow at high altitudes. This in turn led to positive glacier mass balances and caused glaciers to advance. However, during the LGM, despite cooler temperature than in MIS 3, the weakened south Asian monsoon and the associated reduced precipitation were not as favourable for glacier expansion as in MIS 3.