陇西盆地末次冰期黄土粒度特征及其环境意义

顺着风成堆积物搬运的主导方向,对黄土高原西部的末次冰期以来的24个风成堆积物剖面的粒度进行了系统分析,对比各个粒度指标,分析了粒度的空间分布特征,提取了最为敏感的粒度指标,并在南北向大断面上建立了砂的百分含量与沙漠距离的数学模型,该模型与黄土高原中部有所不同。

Environmental Significance and Characteristics of Grain Size of the Loess in Longxi Basin during the Last Glacial Period

Chinese loess-paleosol sequence has provided the most detailed terrestrial records of climate changes in Quaternary. The aeolian sand and dust has been taken as an important proxy of expansion and contraction of the desert during geological period. The signals of the desert evolution were well p reserved in the aeolian deposits on the margin of the desert, which are effective to reconstruct the desert expansion and contraction. According to the dominantwind direction, generally NW-SE, we systematically studies 24 sections ofMalan loess in the west of Chinese Loess Plateau during the Last Glacial period. Detailed granular analyses show the properties of temporal and spatial of theMalan loess, and reducing of the percentage of the sand from northwest to southeast. Our study indicates that the proxies such asD 4, 3 ] , the fraction > 40μm (%) , the fraction > 63μm (% ) , and theMode are more sensitive than any other proxy. A new linear correlation model of sand percentage and distance are established, which shows different pattern to the east of the Chinese Loess Plateau.