鄂尔多斯盆地东缘泥质岩黏土矿物特征及其地质意义

发布时间：2018-08-25 12:50

【摘要】：为研究鄂尔多斯盆地东缘石炭二叠纪古气候特征及其与成煤作用之间的关系,利用X射线衍射(XRD)及扫描电子显微镜(SEM)对研究区石炭二叠系泥质岩中的黏土矿物组成及其环境意义进行分析。结果显示,区内泥质岩中黏土矿物主要以高岭石、伊利石/蒙皂石混层矿物为主,次为伊利石和绿泥石。黏土矿物的垂向组合特征表现为:高岭石在桥头剖面、扒楼沟剖面和成家庄剖面山西组,桥头剖面太原组底部、成家庄剖面太原组上部及本溪组中部含量偏高。伊利石在各个剖面的山西组中含量较高,绿泥石仅在山西组中上部、太原组下部含量较高。扫描电镜下黏土矿物晶体形态规则,未见明显磨蚀痕迹,伊利石结晶度为0.42°Δ2θ~0.63°Δ2θ,平均值为0.47°Δ2θ,结晶度较好,混层比相对质量分数平均值25.1%,表现为自生黏土矿物。根据自生黏土矿物的习性指出研究区古气候总体表现为温暖潮湿、间或在太原组早期和山西组中—晚期伴有短周期干冷气候。古气候与沉积环境两者相互印证指示聚煤作用强度的变化过程,是控制研究区内聚煤作用的关键因素。
[Abstract]:In order to study the characteristics of Permian paleoclimate in the eastern margin of Ordos Basin and its relationship with coal-forming process, The composition and environmental significance of clay minerals in Carboniferous Permian argillaceous rocks in the study area were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the clay minerals in the mudstone are mainly kaolinite, Illite / montmorillonite mixed layer mineral, followed by Illite and chlorite. The vertical assemblage characteristics of clay minerals are as follows: the content of kaolinite in the Qiaotou section, the Chaolougou section and the Chengjiazhuang section of Shanxi formation, the bottom of the Taiyuan formation in the Qiaotou section, the upper part of the Taiyuan formation in the Chengjiazhuang section and the central part of the Benxi formation are relatively high. The content of Illite is higher in Shanxi formation, chlorite is only in the middle and upper part of Shanxi formation, and the lower part of Taiyuan formation is higher. Under scanning electron microscope, the morphology of clay minerals is regular, and there is no obvious abrasion trace. The crystallinity of Illite is 0.42 掳螖 2 胃 (0.63 掳螖 2 胃) and the average value is 0.47 掳螖 2 胃. The crystallinity is good. The average relative mass fraction of mixed layer is 25.1%, which shows that Illite is an authigenic clay mineral. According to the habit of authigenic clay minerals it is pointed out that the paleoclimate in the study area is generally warm and humid sometimes in the early Taiyuan formation and the middle to late Shanxi formation accompanied by a short period of dry and cold climate. Paleoclimate and sedimentary environment are the key factors controlling coal accumulation in the study area.
【作者单位】：陕西煤田地质勘查研究院有限公司;陕西能源集团研究院有限公司;中国矿业大学(北京)地球科学与测绘工程学院;中国神华海外开发投资有限公司;
【基金】：中国地质调查局课题(1212011220794) 国家自然科学基金项目(41572090)~~
【分类号】：P618.11

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