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    碳酸盐矿物阴极发光性的控制因素分析

    Controlling factors of cathodeluminescence of carbonate minerals

    • 摘要: 碳酸盐矿物的阴极发光性主要受其Mn2+和Fe2+含量,以及Mn2+/Fe2+值的综合控制,但Mn2+/Fe2+值的控制作用强一些。研究中充填裂缝的方解石胶结物样品主要采自北京西山寒武系和奥陶系的碳酸盐岩地层中。此外,还从北京石花洞中采集了现代溶洞的石笋样品。样品的阴极发光强度可分为不发光、暗、中等和亮,阴极发光颜色也相应地分为不发光、橙红色、橙黄色和亮黄色。通过对野外露头样品进行电子探针研究,测定其中的Mn2+和Fe2+的含量,并结合样品的阴极发光颜色和强度,得出Mn2+含量要在0.01%以上,Fe2+含量至少在0.8%以下,Mn2+/Fe2+在0.05以上,方解石胶结物才能发光。经研究发现,充填裂缝中方解石胶结物的阴极发光性与Mn2+和Fe2+含量,以及Mn2+/Fe2+值之间存在如下关系:不含Mn2+,Fe2+微量,Mn2+/Fe2+为0时,不发光;0.052+/Fe2+<0.2时,发光强度暗,发光颜色为橙红色;0.22+/Fe2+<2时,发光强度中等,发光颜色为橙黄色;Mn2+/Fe2+>2时,发光强度亮,发光颜色为亮黄色。

       

      Abstract: Cathodelum inescence of carbonate minerals tends to be constrained by the Mn2+ and Fe2+ contents and Mn2+ /Fe2+ ratios.In this study,the calcite cement samples were mostly collected from the Cambrian and Ordovician carbonate rock strata in the Western Hills,Beijing.The cathodeluminescence intensities of these samples can be divided into nonluminous,weak,moderate and bright types.Correspondingly,the cathodeluminescence colours include nonluminescence,salmon,orange and bright yellow colours.The correlation of the cathodeluminescence intensities and colours based on the microprobe analysis,and the Mn2+ and Fe2+ contents and Mn2+ /Fe2+ ratios has led us to the following conclusions.The calcite cement exhibits no luminescence when there is no Mn2+ or only a trace amount of Fe2+ in the samples,and the Mn2+/Fe2+ ratios is 0.The calcite cement exhibits a weak luminescence and salmon when the Mn2+/Fe2+ ratios range between 0.05 and 0.2.The calcite cement exhibits a moderate luminescence and orange when the Mn2+/Fe2+ ratios range between 0.2 and 2.The calcite cement exhibits a bright luminescence and bright yellow when the Mn2+/Fe2+ ratios go up to more than 2.

       

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