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应用 X 射线衍射分析方法对泥岩的矿物成分和含量进行了研究,发现部分矿物在水西沟群中的分布存在很大的差异:高岭石多分布于早侏罗统八道湾组和三工河组,平均含量高达 36.25%;长石仅分布于中侏罗统的西山窑组,且含量较少,平均约为 4.86%;绿泥石在八道湾组和三工河组中含量极少,平均仅为 2.5%,而在西山窑组中分布较多,平均可达 26.57%;蒙脱石在八道湾组和三工河组中含量相对较少,平均为 3.75%,而在西山窑组中相对较多,平均为 7.84%。结合扫描电镜分析对泥岩矿物的成因进行了研究,认为从八道湾组到西山窑组的成岩环境有由偏酸性向偏碱性过渡的趋势,而三工河组具有偏酸性的沉积环境。这说明应用泥岩作为地层对比的辅助标志具有一定的可行性,对成岩或沉积环境的细微解释也具有一定的可行性。同时,西山窑组中铀的两个主含矿层均为偏碱性环境,对铀质在还原条件下沉淀富集也是较好的印证。
The mineral composition and content of mudstone were studied by X-ray diffraction analysis. The distribution of some minerals in Shuixigou group was found to be quite different: kaolinite was distributed in the early Jurassic Badaowan Formation and Sanjiao The average content is as high as 36.25%. The feldspar is only distributed in the middle Jurassic Xishanyao formation, with an average content of about 4.86%. Chlorite was very low in the Badaowan and Sangonghe formations , An average of only 2.5%, while in the Xishanyao Formation more evenly, with an average of up to 26.57%; montmorillonite in the Badaowan and Sangonghe Formation is relatively small, with an average of 3.75%, while in the Xishan kiln Relatively more in the group, with an average of 7.84%. Combined with the scanning electron microscopy analysis of the origin of the mudstone minerals, it is considered that the diagenetic environment from the Badaowan Formation to the Xishanyao Formation tends to transition from acidic to alkaline, while the Sangonghe Formation has acidic depositional environment. This shows that it is feasible to use mudstone as an auxiliary marker for stratigraphic correlation and it is also feasible to explain subtle diagenesis or sedimentary environment. At the same time, the two main ore-bearing layers of uranium in Xishanyao Formation are all alkaline, confirming the precipitation enrichment of uranium under reducing conditions.