山西寿阳地区离石黄土中完型钙质结核矿物成分及结晶特征研究

Study on mineral contents and crystallization characteristics of calcareous nodules in loess of Shouyang area,Shanxi Province

为探究离石黄土中完型钙质结核矿物成分与结晶特征,以山西寿阳地区离石黄土中具有代表性的完型钙质结核为研究对象,利用X射线衍射(XRD)分析完型钙质结核中矿物质量分数,运用扫描电子显微镜(SEM)观察矿物颗粒分布、形状和结晶程度,根据能谱图元素质量分数确定结核内部致密程度、矿物分布、矿物形态和接触关系。结果表明:结核矿物成分为方解石、石英、黏土、斜长石和钾长石等,方解石明显向中心迁移;由外层向中心,方解石质量分数增加了16%,其他矿物减少了34%~47%;结核内部碳酸盐均为次生微晶方解石,说明结核形成时温度较低。研究结果可为类似条件下黄土中钙质结核的形成与气候演化提供理论依据和工程参考。

In order to explore the mineral composition and crystallization characteristics,the typical gestalt calcareous nodules in Lishi loess in Shouyang area of Shanxi Province were taken as the research object.The mineral mass fraction in complete calcareous nodules were analyzed by X-ray diffraction(XRD),the distribution,shape and crystallization degree of mineral particles were observed by scanning electron micro⁃scope(SEM),and the internal density,mineral distribution,mineral morphology and contact relationship of nodules were determined according to the element mass fraction of energy spectrum.The results showed that the mineral composition of nodules was calcite,quartz,clay,plagioclase and potassium feldspar,and cal⁃cite migrated to the center obviously.From the outer layer to the center,the volume fraction of calcite in⁃creased by 16%,while other minerals decreased by 34%~47%.The carbonates inside the nodules were all secondary microcrystalline calcite,which indicated that the temperature was low when the nodule was formed.The research results could provide theoretical basis and engineering reference for the formation and climate evolution of calcareous nodules in loess under similar conditions.