内蒙古苏宏图地区黏土岩矿物组成与地球化学特征

为探究内蒙古苏宏图地区黏土岩的地球化学特征、沉积物质来源和构造环境，利用多晶X射线衍射（XRD）和ICP-AES/MS分析法对苏宏图地区SZK-2井20件黏土岩岩芯样品进行分析测试。结果表明：XRD分析显示苏宏图地区黏土岩中黏土矿物组成以伊利石为主，伊利石质量分数平均值为37.64%；与大陆上地壳相比，黏土岩相对富集SiO2、Al2O3、Zr、As，贫P2O5、MgO、MnO、Cr、Ni，两者的K2O、TiO2、Sr、Ba含量接近。黏土岩中稀土元素特征为轻稀土元素富集，重稀土元素相对亏损，表现为明显的右倾，出现明显的Eu（平均值=0.60）负异常和Ce（平均值=1.01）轻微负异常，与大陆上地壳稀土元素的配分模式较为相似；K2O/Na2O-SiO2和微量元素构造背景判别图解中，样品多数落在大陆岛弧区，少量落在活动大陆边缘，反映了苏宏图地区沉积时期的物源来自于上地壳长英质物源且形成于大陆岛弧的构造背景中。

Mineral composition and geochemical characteristics of claystones in the Suhongtu area, Inner Mongolia

In order to explore the geochemical characteristics, sedimentary material sources and tectonic setting of claystones in the Suhongtu area of Inner Mongolia, this work conducted polycrystal X-ray diffraction (XRD) and ICP-AES/MS analysis to analyze and test 20 claystone core samples from the Well SZK-2 in the Suhongtu area. The results show that the claystone in the Suhongtu area is dominated by illite, whose average content can reach up to 37.64%. Compared with the continental upper crust, the claystone is relatively enriched in major elements of SiO2, Al2O3, Zr and As, and is depleted in P2O5, MgO, MnO, Cr and Ni, with similar K2O, TiO2, Sr and Ba contents for both. The rare earth elements are characterized by enrichment of LREE and relative depletion of HREE, and show obvious right inclination and the presence of negative Eu anomaly (mean=0.60) and weak negative Ce anomaly (mean=1.01), which is basically similar to the REE distribution patterns of the continental crust. In the K2O/Na2O-SiO2 diagram and discrimination diagram of trace element tectonic background, most samples fall in continental island arc, and few fall on active continental margin, reflecting that the material in the Suhongtu area was derived from the upper crust felsic material and was formed in a continental island arc setting.