川南煤田观文勘探区煤中Ge、Ga的赋存特征及影响因素

Occurrence characteristics and influencing factor of Ge and Ga of the coal seam in Guanwen exploration area of South Sichuan coalfield

稀散金属锗(Ge)、镓(Ga)作为重要的战略性矿产资源,在煤中分布较为广泛。为查明川南煤田观文勘探区煤中Ge、Ga富集情况及控制因素,笔者基于川南煤田观文勘探区地质勘查资料,分析二叠系龙潭组煤中Ge、Ga的分布情况并总结其赋存特征,并采用相关性分析、R型聚类分析等方法探讨煤中Ge、Ga的影响因素并讨论其地球化学特性。结果表明:观文勘探区煤中Ge、Ga平均含量分别是3~4μg/g、5~11μg/g,均为正常水平;含煤岩系垂向剖面上,Ge平均含量较为稳定,Ga平均含量则具“先减后增”的变化趋势,且潮坪-海湾成煤环境有利于Ga的赋存;镜质组为影响煤中Ge赋存的主要因素,煤中Ga的赋存主要受到灰分(黏土类、硫化物类矿物)影响,而煤层厚度及变质程度对煤中Ge、Ga赋存无明显作用;煤中Ge具有亲有机质的特性,或以Ge的络合物形式赋存于镜质组中;煤中Ga呈无机亲和性,或以类质同象的形式赋存于黏土类、硫化物类矿物中。研究成果可为今后在川南煤田寻找“煤型关键金属矿床”提供参考。

As the important strategic mineral resources,the rare metals Ge and Ga are widely distributed in the coal seam.In order to find out the enrichment regularity and controlling factor of Ge and Ga of the coal seam in Guanwen exploration area of South Sichuan Coalfield,on the basis of the geological survey data of Guanwen exploration area,the distribution feature of Ge and Ga in coal seam of Permian Longtan Formation is analyzed and summarized.Correlation analysis and R-type cluster analysis are used to explore for the influencing factor of Ge and Ga in coal seam and discuss their geochemical properties.The result shows that the average contents of Ge and Ga in the coal seams of Guanwen exploration area are 3-4μg/g and 5-11μg/g respectively,which are in the normal level.The average content of Ge is relatively stable in the vertical profile of coal-bearing rock system,while the average content of Ga has a trend of"decreasing first and then increasing".And the chaopeng-bay coal-forming environment is conducive to the deposition of Ga.The specular group is the main factor influencing the occurrence of Ge in coal,the occurrence of Ga in coal is mainly influenced by ash(clay-like and sulphide-like minerals),while the thickness of the coal seam and metamorphism degree have no significant effect on the occurrence of Ge and Ga in coal.Ge in coal is organophilic or occurs as a complex of Ge in the specular group.Ga in coal is inorganic or occurs as a homogeneous form in clay and sulphide minerals.The research result can provide a reference for the future search of"coal-type key metal deposit"in South Sichuan coalfield.