库姆塔格沙漠形成时代及演化过程研究

Kumtagh Desert is an important part of the Central Asian desert, located in the extremely arid area of northwest inland of China and famous for the unique feather dunes in the world. The research of the formation age and the evolution has foremost scientific significance to reveal the formation process of arid climate and the environment of the Northwest inland and the response of the Tibetan Plateau uplift and global changes..On basis of the field survey and the contrast of regional stratigraphic section, the researchers chose high-resolution stratigraphic section (including the antiquity into the sand section, the lacustrine section, as well as different sedimentary layer of the contact section) to depict and observe the sedimentary facies, structural features and systemly high-density sampling. The indoor time monitoring, multiple Indicators (such as particle size, magnetic susceptibility, elemental geochemistry, pollen, etc.), extraction and analysis of high-precision information about the climate and environment information can determine the formation age of the desert ,establish the evolution time series of the research region, restore the history of climate change ,then compare with the global glacial - interglacial climate changes and the uplift of Qinghai-Tibet Plateau,can reveal a cause and effect relationship of them.

库姆塔格沙漠是中亚沙漠的重要组成部分，地处中国西北内陆极端干旱区，以独特的羽毛状沙丘称著于世。对其形成时代与演变的研究，对揭示西北内陆干旱气候与环境的形成过程以及对青藏高原隆升和全球变化的响应都具有重要的科学意义。在野外调查和区域地层对比基础上，选择高分辨率的地层剖面（包括古风成砂剖面、河湖相剖面等，以及不同沉积相互层接触的剖面）进行沉积相、结构特征等的观察描述和系统的高密度采样，在室内进行年代测定和多指标（如粒度、磁化率、元素地球化学、孢粉等）的、高精度的气候与环境信息的提取分析，确定沙漠形成时代，建立沙漠演变的时间序列，恢复气候变迁历史，并与全球冰期-间冰期气候变化和青藏高原隆升对比，揭示它们之间的因果关系。

库姆塔格沙漠地处我国西北内陆干旱区，其形成时代与演化研究有助于揭示内陆极端干旱区气候与环境变化。通过对含古风成砂、河湖相地层剖面的观察、地层关键层位年代测定以及反映气候与环境变化代用指标的测试分析，对该沙漠形成时代与沉积物性质有初步了解。研究结果表明：沙漠形成于早更新世200万年左右，大体上与黄土高原L31/L32形成时代相当，与北半球冰期降温时间相一致；沙漠发育经历了早更新世湖泊萎缩与沙漠零星发育阶段、中更新世沙漠大规模发育阶段以及晚更新世形成现代沙漠景观阶段3个阶段。该沙漠地表沙丘砂以及典型线性沙丘砂的粒度组分以中砂、细砂和极细砂为主，但存在区域差异；地表沉积物化学元素特征反映出弱的化学风化过程。