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通过扫描电镜观察和全岩矿物X-射线衍射实验图谱分析发现,鄂尔多斯盆地延长组页岩中含有一定量的非晶态二氧化硅。现有的3种计算非晶态二氧化硅含量的方法都有一定的缺陷:化学溶蚀方法分析周期长、且对其他矿物有一定程度的溶解,影响了定量分析的精度;X-射线衍射定量分析法需要计算非晶态二氧化硅衍射图谱上圆丘散射曲线的积分强度,人为误差较高;增量法需要配制标样,但有些种类纯矿物难以获得,标样难以配制,而且误差较高。在总结前人研究的基础上,提出了全岩矿物X-射线衍射与微区矿物定量分析相结合的方法来计算多相体系中非晶态二氧化硅含量这一问题。该方法避开了前人所提出方法的缺点,分别计算得到了结晶态石英含量与二氧化硅含量,从而间接计算出非晶态二氧化硅含量,利用该方法求得鄂尔多斯盆地延长组2个样品非晶态二氧化硅含量分别为3.4%和14.02%。
Scanning electron microscopy and whole rock mineral X-ray diffraction experimental analysis of the spectrum found that the Ordos Basin Yanchang shale contains a certain amount of amorphous silica. The existing three methods for calculating the content of amorphous silica all have certain defects. The chemical dissolution method has a long period of analysis and a certain degree of dissolution to other minerals, which affects the accuracy of quantitative analysis. X-ray diffraction The analytical method needs to calculate the integrated intensity of the scattering curve of the dome on the amorphous silicon dioxide diffraction pattern, and the human error is high. The incremental method needs to prepare the standard sample, but some pure minerals are difficult to obtain and the standard sample is difficult to formulate, high. On the basis of summarizing the previous studies, the method of combining the whole rock mineral X-ray diffraction and the micro-area mineral quantitative analysis was proposed to calculate the amorphous silica content in the multi-phase system. This method avoids the shortcomings of the previous proposed method, calculated the crystalline quartz content and the silica content, and indirectly calculated the amorphous silicon dioxide content, using this method to obtain the Ordos Basin Yanchang two Amorphous silica samples were 3.4% and 14.02% respectively.