Luminescence chronology of late Quaternary moraines and Last Glacial Maximum equilibrium-line altitude reconstruction from Parlung Zangbo Valley, south-eastern Tibetan Plateau
Luminescence chronology of late Quaternary moraines and Last Glacial Maximum equilibrium-line altitude reconstruction from Parlung Zangbo Valley, south-eastern Tibetan Plateau
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青藏高原东南部帕隆藏布河谷晚第四纪冰碛的发光年代学和末次盛冰期平衡线高度重建
DOI：
10.1002/jqs.2733
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发表时间：
2014
影响因子：
2.3
通讯作者：
Yingbin Deng
中科院分区：
文献类型：
--
作者：
RenRong Chen;ShangZhe Zhou;ZhongPing Lai;XianJiao Ou;Rong Chen;Yingbin Deng
对青藏高原东南部Parlung Zangbo山谷（Daba和Charao）的冰川沉积物样品进行了光释光测年，以更好地限制晚第四纪冰川作用的时间，这被认为与印度季风有关。石英上的单等份再生剂量方案用于使用小等份进行等效剂量（De）测定。对于大坝流域的样品，使用两种粒度级（中等（38-63 µm）和粗粒（90-250 µm））进行了年龄比较。大坝谷（P3）和查绕谷（P7）的粗颗粒年龄为16.4 ~ 26.0ka，与已发表的白玉谷（PB 1）宇宙成因放射性核素暴露年龄一致。我们的测年结果表明，这些冰碛形成于末次盛冰期（LGM）。然后，我们重建了研究区五个冰川山谷在LGM期间的过去平衡线高度（ELA），范围从3286到4014 m，平均值为3730 m，而当代平均ELA为4655 m。经过地形抬升（自末次盛冰期以来约8 m）校正后，末次盛冰期与现今的ELA值相差917 m。根据这些数据，末次盛冰期的估计温度比Parlung Zangbo河谷现在的温度低6.3 °C。
Optically stimulated luminescence dating was applied to samples from glacial sediments in the Parlung Zangbo Valleys (Daba and Charao) of the south‐eastern Tibetan Plateau to better constrain the timing of Late Quaternary glaciation, which is thought to have been linked to the Indian monsoon. The single aliquot regenerative‐dose protocol on quartz was used for equivalent dose (De) determination using small aliquots. For samples from the Daba Valley, the comparison of ages using two grain size fractions, middle (38–63 µm) and coarse (90–250 µm) were conducted. The coarse grain ages in the Daba Valley (P3) and Charao Valley (P7) range from 16.4 to 26.0 ka, and are consistent with previously published cosmogenic radionuclide exposure ages in the Baiyu Valley (PB1). Our dating results reveal that these moraines were formed during the Last Glacial Maximum (LGM). We then reconstruct the past equilibrium‐line altitudes (ELAs) during the LGM for five glacial valleys in the study area, which range from 3286 to 4014 m with an average value of 3730 m, while the contemporary average ELA is 4655 m. After correction for terrain uplift (about 8 m since the LGM), the difference in the ELA values between the LGM and today is 917 m. According to these data, the estimated temperature during the LGM is 6.3 °C lower than present for the Parlung Zangbo River Valley.