摘要
采用岩性描述以及OSL和ESR测年方法,研究内蒙古托克托台地郝家窑剖面和郝家窑钻孔的地层时代。研究表明,郝家窑剖面出露地层厚度47.0 m,湖相层顶部的年龄约为距今100 ka,剖面底部的年龄约为距今150 ka。郝家窑钻孔岩性大致分3段:0～12.77 m为棕黄色粉砂质黏土、黏土质粉砂,OSL年龄为距今120～40 ka,应属晚更新世马兰黄土;12.77～72.23 m为淡黄绿、灰褐色粉、细砂层和粉砂质黏土,湖相沉积层,OSL年龄约为距今400～100 ka,属上更新统—下更新统;72.23～118.45 m为棕红色粉砂质黏土层夹钙质层,属受流水影响的风成黄土,ESR年龄为距今476～990 ka,对应于中更新统离石黄土。托克托湖相层的时代与萨拉乌苏河流域经典的萨拉乌苏组(距今75～150 ka)有较大差距,似乎不宜归入萨拉乌苏组,建议暂称为托克托组。
A set of later Quaternary fluvial-lacustrine strata is widely distributed in the Hetao region, which is compared with Salawusu Formation by predecessors. The Togtoh mesa is located in the east of the Hetao plain, and forms the geomorphic second platform. The lacustrine strata are well-exposed along the east bank of the Yellow River at the front edge of Togtoh mesa. The article mainly studied on the age of Haojiayao section and Haojiayao drill core section by lithological description as well as OSL and ESR dating methods. The emergence stratum of Haojiayao section is 47 m thick, the age at the top of lacustrine formation is about 106 kaBP, and the bottom is about 150 kaBP. Base on the lithological character, the Haojiayao drill core section can be divided to three parts： 0 -12.77 m is a set of brownish yellow silty clay and clayey silt layers, which should be the Late Pleistocene Malan Loess, and its OSL age is 106 -40 kaBP; 12.77 -70.23 m is a set of chartreuse, taupe silt and silty clay layers which should be lacustrine deposition, with OSL age being about 400 - 106 kaBP which belongs to Late Pleistocene; 70.23 - 118.45 m is a set of brownish red silty clay layers with calcareous interlayers, that should be the eolian loess which was influenced by water, its ESR age is about 476 - 990 kaBP, and corresponds to the Middle Pleistocene Lishi Loess. The Togtoh lacustrine strata should not belong to the Salawusu Formation, because of the large differences between the age of classic Salawusu Formation and the Salawusu river basin which is about 75 - 150 kaBP.
出处
《地质力学学报》
CSCD
2013年第1期1-13,共13页
Journal of Geomechanics
基金
国家自然科学基金项目(40972223)
中国地质调查局项目(1212010711705)
