云南元谋龙街粉砂层的粒度特征与成因

对云南元谋龙街粉砂层保存较好的龙街剖面进行了年代地层学和沉积学研究。该剖面厚40.6m，距顶部10.9m处14C年龄为26305±1152a BP，指示龙街粉砂层的地质时代为晚更新世。粒度分析结果显示，龙街粉砂层主要由粉砂组成，中值粒径的平均值为15.28μm，频率曲线呈现明显的双峰特征，几乎没有粗尾。与内蒙古岱海湖相沉积、甘肃西峰黄土、安徽宣城河流沉积的粒度分布及粒度参数特征对比，龙街粉砂层与岱海湖泊沉积的粒度特征基本一致，而与西峰黄土及宣城河流相沉积明显不同，表明龙街粉砂层是水动力较弱的湖泊沉积物。

Grain-size characteristics and origin of Longjie silt layer in the Yuanmou area, Yunnan, China. Geological Bulletin of China

Chronostratigraphy and sedimentology study of Longjie section where silt layers are well preserved in Yuanmou area of Yunnan province. Approximate thickness of this section is 40.6m, the 14C dating result from where 10.9m away from the top is 26305±1152 a BP，which indicates that the silt layer belongs to Late Pleistocene. By grain-size analyzing，Longjie silt layer is mainly composed by silt, medium size is 15.28μm, and the frequency curve displays a distinct doule-peak feature barely without any crude tailings. Compared to the grain-size distribution and parameter of Daihai lake sediment, Xifeng yellow earth and Xuancheng fluvial sediments, grain-size feature of Longjie silt layer is generally the same with that of Daihai lake deposit, while is quite distinct from yellow earth and fluvial sediments, this indicates that Longjie silt layer is lacustrine deposit under relatively low hydrodynamic force.