Cosmogenic 10Be dating of the oldest moraine in the Hengduan Mountains
The Hengduan Mountains is in the transitional zone between the Qinghai-Tibet Plateau (QTP) and the Yunnan-Guizhou Plateau in China, and a key area for elucidating the Quaternary environmental changes in Asia. The paleo-Daocheng ice cap was located on the Shaluli Hilly Plateau in the northeastern Hen...
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Veröffentlicht in: | Science China. Earth sciences 2023-10, Vol.66 (10), p.2211-2223 |
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Zusammenfassung: | The Hengduan Mountains is in the transitional zone between the Qinghai-Tibet Plateau (QTP) and the Yunnan-Guizhou Plateau in China, and a key area for elucidating the Quaternary environmental changes in Asia. The paleo-Daocheng ice cap was located on the Shaluli Hilly Plateau in the northeastern Hengduan Mountains, the oldest moraines in the Hengduan Mountains region were found in the ice cap area. Such glacial landforms provide key evidence to study the timing when this area entered the cryosphere with the uplift of the QTP. However, it is difficult to collect suitable glacial boulders from these moraines for traditional terrestrial
in-situ
cosmogenic nuclide (TCN) exposure dating because of long-term severe moraine degradation. Here, we collected clast samples from the moraine surface and depth profile to constrain the age of the oldest moraine in Kuzhaori (moraine E) using TCN
10
Be dating technique. The minimum
10
Be ages of five clast samples from the moraine surface range from 187.4±1.5 to 576.8±4.3 ka, implying that the moraine has been seriously degraded since deposition. Based on the TCN
10
Be concentrations of the samples from a depth profile and simulations, the exposure-erosion-inheritance history of the profile was obtained. By fitting to the profile
10
Be concentrations using the chi-square test, the simulations yielded a reliable age of 626.0±52.5 ka for the moraine. Therefore, the oldest moraine (moraine E) in Kuzhaori was most likely formed at about 0.63 Ma ago, corresponding to the marine isotope stage (MIS) 16. This glaciation represents the maximum Quaternary glaciation after the QTP was elevated into the cryosphere by the Kunlun-Yellow River Tectonic Movement. |
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ISSN: | 1674-7313 1869-1897 |
DOI: | 10.1007/s11430-022-1167-x |