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    西藏札达盆地及周缘高山区第四纪冰川堆积及冰川进退规程讨论

    Quaternary glacial deposition and glacial advance and retreat in the Zanda basin and its surrounding mountains in Ngari, Tibet

    • 摘要: 提要:札达盆地及周缘高山区的第四纪冰川堆积在空间分布上大致可分为:①盆地周缘高山区U形谷中及山麓地带的冰川堆积;②盆地周边深切峡谷区的冰川堆积;③盆地面上的冰川堆积;④盆地河谷高阶地与沟谷中的冰川堆积;⑤盆地周缘高山区山前地带的冰川堆积等。不同区域分布的冰川堆积,在砾石成分、磨圆度、结构构造、地貌特征等都有较明显区别。依据冰川堆积物的特征、分布等,可将本区第四纪的冰川发展,由老到新划分为:冰缘阶段→冰进阶段→最大冰川阶段→冰退阶段。对应的冰川类型为:山谷、山麓及冰帽冰川发育阶段→大规模冰帽冰川发育阶段→冰帽、山谷及山麓冰川发育阶段。现有资料研究表明,札达盆地及周缘高山区,是青藏高原第四纪冰川堆积发现最多、最全、分布最连续和保存最好的地区。为该区及青藏高原地区的第四纪冰川研究、冰期的划分和对比、气候地层的建立、古气候和古环境的研究等提供了珍贵的基础资料。

       

      Abstract: Abstract:Quaternary glacial deposits of the Zanda basin and its surrounding mountains may be divided in space distribution into:① glacial deposits in U-shape valleys and foothills in the basin and its surrounding mountains, ② glacial deposits in deep-incised valleys around the basin, ③ glacial deposits on the basin surface, ④ glacial deposits on high terraces of river valleys and in gullies of the basin, and ⑤ glacial deposits in piedmont zones of mountains around the basin. Glacial deposits in different areas differ markedly with respect to the gravel composition, roundness, textures and structures, geomorphologic features. The Quaternary glacial development in the region may be divided from early to late times into the periglacial stage, glacial advance stage, biggest glacial stage and glacial retreat stage according to the features and distribution of glacial deposits. The glacial types corresponding to these stages are the valley, piedmont and ice-cap glacier development stage, ice field glacier development stage and ice-cap, valley glacier and piedmont glacier development stage. The existing data indicate that the Zanda basin and its surrounding mountains are areas where the most abundant, complete and continuously occurring and best-preserved Quaternary glacial deposits are found on the Qinghai-Tibet Plateau. This research provides valuable basic data for the study of Quaternary glaciers in this region and the Qinghai-Tibet Plateau, division and correlation of glacial epochs, establishment of climatostratigraphy and climatic and paleoenvironmental studies.

       

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