通过扫描电镜观察和全岩矿物X 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.现有的三种计算非晶态二氧化硅含量的方法都有一定的缺陷:化学溶解方法分析周期长、且对其他矿物有一定程度的溶解;X 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X 衍射与微区矿物定量分析相结合的方法来解决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,然而超高的实验成本也成为该方法在现阶段难以普及的主要原因.
The Yanchang Formation shale of Ordos Basin contains a certain amount of amorphous SiO2, which is proved by SEM observations and X-ray diffraction analyses of bulk rocks. Three methods proposed to calculate the quantity of amorphous SiO2 have their own flaws. The disadvantages of chemical denudation are experimental period and dissolution of other minerals. XRD quantitative analysis possesses high personal errors in the integrated intensity of dome-shaped scattering curves in XRD spectrum of amorphous SiO2. The doping method has high deviation and needs to compound standard sample. On the basis of summarizing previous researches, a new method that combines QEMSCAN and XRD is proposed for calculating the amorphous SiO2 in a multiphase system. The new method avoids the flaws in the three approaches, and calculates the amount of amorphous SiO2 indirectly according to the quantities of quartz and SiO2 measured, respectively. However, super high experimental cost is the main factor to limit the method for wide use.