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

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 microscope（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 calcite migrated to the center obviously. From the outer layer to the center,the volume fraction of calcite increased 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 n