基于定量地学方法分析西藏尼木岗讲矿区与矿有关的地质变量

On geological variables related to minerals based on quantitative method in Gangjiang mine in Nimu County of Tibet

与矿有关的地质变量以及有利成矿变量的分析一般是以地质研究为基础,传统地质分析方法与数学统计方法相结合。西藏尼木岗讲矿区前人已有许多研究,但多以地质分析为主。采用定量地学方法中的信息量法和地质特征向量长度分析法直接对原始样品分析数据进行统计分析,结合前人地质分析结果,总结与矿有关的地质变量及成矿有利因素。对比2种方法的结果发现,信息量法考虑的只是与矿关系密切的因素,只考虑质而不考虑量;地质特征向量长度法在考虑质的基础上还考虑了量,有质但是没有量的变量不具有代表性,不能算作与矿关系密切的变量。最后分析得出:研究区为斑岩型铜钼矿,铜矿与二长花岗岩关系密切,岩体多含斑,似斑状结构,块状构造,与矿关系密切的围岩蚀变有黑云母化、钾化和硅化,其中黑云母化与铜矿体关系最为密切,钾化和硅化最为发育,蚀变程度较强—强时成矿性较好,岩体矿化主要为黄铜矿化和辉钼矿化,孔雀石化虽出现频率较低,但相对上述2种矿化含矿率较高,根据张庆松等人研究表明,孔雀石化为后期次生氧化富集时产生,为铜矿有利成矿标志,矿石多为星点状、浸染状、细脉状构造,其中浸染状和细脉状构造的矿石含矿率较高,为铜矿有利成矿变量,粒状构造和薄膜状构造的矿石在研究区较少见,但含矿率很高,也可作为有利成矿变量。研究区钼矿为伴生矿体,与矿关系密切的变量与铜矿大致相同,辉钼矿化相对于黄铜矿化更有利于钼矿成矿,矿石构造零星状、团块状也与钼矿关系密切。

The previous studies on Gangjiang ore district in Nimu, Tibet were mostly focused on geological analysis. The authors made a statistic analysis on original sample data directly by information value method and geological property vector length analysis method in combination with the summary of geological variables related to minerals and favorable factors to mineralization concluded by the previous studies. The results showed that information value method considered factors closely related to minerals, quality instead of quantity ; geological property vector length analysis method cared about quality based on the consideration of quantity.