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内蒙古河套地区广泛分布着一套晚第四纪河湖相地层,前人将其与萨拉乌苏组对比。托克托台地位于河套盆地最东部,晋陕峡谷上峡口,地貌上构成二级台地。台地前缘湖相地层出露良好。本文主要研究了郝家窑剖面湖相地层的时代与沉积环境。郝家窑剖面出露地层厚约47m:上部为棕黄色粉砂质粘土、粘土质粉砂层,风成黄土,厚约3m;下部为青灰、黄、灰白色粉砂、粘土质粉砂、粉砂质粘土层,湖相地层,厚约44m。湖相层顶部的OSL年龄约100kaB.P.,剖面底部的OSL年龄约为145kaB.P.,地质时代属晚更新世。郝家窑剖面沉积物色度指标显示,L~*曲线和a~*曲线在3m处有明显的转折,之上为风成沉积,之下为湖相沉积。烧失量测试结果,LOI550的最高值为8.39%,最低值为0.44%,平均值为3.16%;LOI950的最高值为18.05%,最低值为0.51%,平均值为6.39%。郝家窑剖面湖相沉积物的亮度L~*和烧失量LOI950的趋势基本同步,由下向上呈波动上升趋势,反映沉积物碳酸盐含量在不断增高,湖水矿化度在增大,指示了湖泊处于封闭的环境,黄河当时可能没有通过河套盆地。托克托地区约于100kaB.P.左右结束湖泊沉积,转型发育风成黄土。
Inner Mongolia Hetao area is widely distributed a set of late Quaternary river lacustrine facies, its predecessors and Sarah Wusu contrast. Tuoketuo platform is located in the easternmost part of the Hetao Basin, Shanxi-Shaanxi Gorge Gap, the topography constitutes a secondary platform. The front of the platform lacustrine strata exposed well. This paper mainly studies the age and sedimentary environment of the lacustrine strata in the Haojiayao section. Haojiayao profile exposed layer thickness of about 47m: the upper is brownish yellow silty clay, clayey silt layer, aeolian loess, thickness of about 3m; the lower part of the gray, yellow, gray silt, clay silt, powder Sandy clay layer, lacustrine formation, about 44m thick. The OSL age at the top of the lake facies is about 100kaB.P. The OSL age at the bottom of the profile is about 145kaB.B., and the geologic age is Late Pleistocene. The sediment hue index of Haojiayao profile shows that the L ~ * curve and the a ~ * curve have a significant turning point at 3m, above which the aeolian deposits and the lacustrine deposits are below. The results of loss on ignition test showed that the highest LOI550 value was 8.39%, the lowest value was 0.44% and the average value was 3.16%. The highest LOI950 value was 18.05% and the lowest value was 0.51% with an average value of 6.39%. The trends of L ~ * and loss on ignition LOI950 of Haojiayao section are basically synchronous and fluctuate upward from bottom to top, reflecting that the carbonate content of sediments is increasing and the salinity of lake water is increasing, Indicating that the lake is in an enclosed environment. The Yellow River may not have passed the Hetao Basin at that time. The Tuoketuo area ended lacustrine deposition at about 100kaB.P., transforming the development of wind into loess.