| 藏东南波堆藏布江流域古乡冰期冰川重建 |
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| 引用本文： | 覃长雄,许刘兵,谢金明,周尚哲.藏东南波堆藏布江流域古乡冰期冰川重建[J].冰川冻土,2021,43(3):724-734. |
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| 作者姓名： | 覃长雄 许刘兵 谢金明 周尚哲 |
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| 作者单位： | 1.华南师范大学 地理科学学院，广东 广州 510631;2.兰州大学 资源环境学院，甘肃 兰州 730000 |
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| 基金项目： | 国家自然科学基金项目(41771065) |
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| 摘 要： | “古乡冰期”是青藏高原第四纪冰川作用中最具代表性的冰期之一，指代的是倒数第二次冰期，其命名依据来源于藏东南波堆藏布江谷地、保存于古乡一带的终碛-侧碛垄，已有的宇宙成因核素10Be暴露测年结果显示其发生于海洋氧同位素阶段（MIS）6。然而，古乡冰期时波堆藏布江流域冰川作用范围、冰量及平衡线高度（ELA）等关键信息，仍有待进一步研究。结合冰川地貌野外考察、高清遥感影像/卫星照片及绝对数值年龄，对波堆藏布江流域古乡冰期时的冰川作用范围进行了重建，在此基础上结合数字高程模型，运用冰面纵剖面模型对波堆藏布江流域古乡冰期时古冰川进行了数值模拟。结果显示：古乡冰期时流域内冰川的平均厚度约360 m，冰川总面积为2 648 km2，体积约为953 km3，流域内的冰川覆盖率由古乡冰期时的63%缩减至现在的22.4%。此外，运用积累区面积比率（AAR）法和末端-源头高度比率（THAR）法对波堆藏布江流域现代和古乡冰期时的冰川平衡线高度进行了估算。其中，现代冰川ELA为4 455 m，基于反距离加权法插值的古冰面高程计算出古乡冰期时ELA为3 871 m，比现代ELA低了584 m，古冰川ELA估算结果与前人结果基本一致。
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| 关 键 词： | 古乡冰期 波堆藏布江 冰川重建 平衡线高度 积累区面积比率 末端-源头高度比率 |
| 收稿时间： | 2021-06-01 |
| 修稿时间： | 2021-06-11 |
Glacier reconstruction of the Guxiang Glaciation in the Bodui Zangbo Valley in southeastern Tibet |
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| QIN Changxiong,XU Liubing,XIE Jinming,ZHOU Shangzhe.Glacier reconstruction of the Guxiang Glaciation in the Bodui Zangbo Valley in southeastern Tibet[J].Journal of Glaciology and Geocryology,2021,43(3):724-734. |
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| Authors: | QIN Changxiong XU Liubing XIE Jinming ZHOU Shangzhe |
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| Institution: | 1.School of Geography，South China Normal University，Guangzhou 510631，China;2.College of Earth and Environmental Sciences，Lanzhou University，Lanzhou 730000，China |
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| Abstract: | The Guxiang Glaciation is one of the most typical glaciations on the Tibetan Plateau during the Quaternary and has been widely used to represent the penultimate glaciation on the plateau. It was named from the frontal-lateral moraine at Guxiang， over 100 km down valley from the source area around the Guanxing Glacier， in the Bodui Zangbo River catchment in southeastern Tibet. Existing cosmogenic radionuclide 10Be surface exposure ages （~130 ka） show that the Guxiang Glaciation occurred during marine oxygen isotope stage 6， however， key information， such as ice volume， ice extent， and equilibrium line altitude （ELA） in the Bodui Zangbo River catchment during the Guxiang Glaciation， is an open question. In this study， we reconstruct the ice extent of the Guxiang Glaciation for the whole catchment on the basis of repeated field investigations， existing numerical dating results of moraines， and high-definition remote sensing images/satellite photos； estimate the ice volume and ice thickness using a glacier surface profile model run in Excel and ArcGIS software； and estimate the ELA of the catchment during the Guxiang Glaciation using the accumulation area ratio （AAR） and toe-to-headwall altitude ratio （THAR） methods. Our results show that during the Guxiang Glaciation， the total glacier area was 2 648 km2， the average glacier thickness was nearly 360 m， and the ice volume around 953 km3. The ice-cover rate has decreased from 63% in the Guxiang Glaciation to the present cover rate of 22.4%. Based on the paleo-glacier surface elevation interpolated with the inverse distance weighting method， the Guxiang Glaciation ELA is estimated to be 3 871 m， which is 584 m lower than the present ELA of 4 455 m. Our ELA estimation result is consistent with existing values. |
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| Keywords: | Guxiang Glaciation Bodui Zangbo River glacier reconstruction equilibrium-line altitude （ELA） accumulation area ratio （AAR） toe-to-headwall altitude ratio （THAR） |
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