【摘要】 萨拉乌苏河流域米浪沟湾剖面萨拉乌苏组含7层古流动沙丘砂、4层古固定—半固定沙丘砂。对这些沙丘砂的沉积构造观察以及粒度、扫描电镜和常量化学元素分析结果表明:(1)这些沙丘砂具有与现代沙丘砂相似的风成沉积构造特征;(2)粒度及其参数——Mz、!、Sk和Kg,以及主要化学组分SiO2、Al2O3和TOFE也与现代沙丘砂相近;(3)Mz-"、SiO2-Al2O3+TOFE散点图和概率累积曲线显示这些沙丘砂与萨拉乌苏组中的河湖相、古土壤差别明显,而与现代沙丘砂一致;(4)石英砂颗粒具有良好的磨圆以及碟形坑、新月形坑、麻坑、上翻解理薄片、硅质沉淀和硅质裂纹等表面结构特征,反映其曾受持久的风力搬运作用。沉积构造、粒度、石英砂颗粒表面结构和化学元素等多个方面具备了与现代沙丘砂类似的风成特征,证明这些沙丘砂的成因是风成的。更多还原

【Abstract】 The Salawusu Formation of Milanggouwan section in Salawusu River Valley includes 7 layers of paleo-mobile dune sands,and 4 layers of paleo-fixed and semi-fixed dune sands.We have observed the structure of these dune sands and analyzed the grain-size,surface textural features and several main chemical elements of them,the results showed that:(1) these dune sands have some eolian structure characteristics which are similar to the recent dune sands;(2) they are also similar to the recent dune sands in grain-size components,and parameters of Mz,?滓,Sk and Kg,as well as in several main chemical components;(3) the scatter plots of Mz-?滓,SiO2-Al2O3+TOFE and the probability curves of grain-size showed that these paleo dune sands are different from paleosols and fluvio-lacustrine facies but are consistency with recent dune sands;and(4) the quartz sands have well roundness and some surface textural features such as dish-shape pits,crescent-shape pits,pockmarked pits,upturned cleavage plates,siliceous precipitates and siliceous crevasses,indicating that they had been carried for a long time by the wind.As the 11 layers of paleo dune sands possess the eolian characteristics in structure,grain-size,surface textural features and chemical elements,the origin of their formation should be eolian.更多还原