安徽宁国东山坞地区土壤地球化学特征与评价

Characteristics and evaluation of soil geochemical anomalies in Dongshanwu area,Ningguo,Anhui Province

通过对东山坞地区土壤元素含量进行数学地质分析及单元素异常评价可知,研究区土壤中Au、As和Ag、Mo、Sb之间具有良好的亲和性,Ag、Mo在研究区黑色岩系中具高背景;Sb浓度克拉克值及变异系数大,指示Sb卷入了成矿作用,深部工程已发现锑工业矿体,预示研究区锑找矿前景较好;Au和As的异常范围一致性较好,Au为富集元素,变异系数最大,说明矿化不均匀,Au矿化与赋存的构造蚀变岩相关,与硅化呈正相关。通过土壤测量工作在研究区圈定了4个土壤地球化学异常区,其中Ⅰ、Ⅱ和Ⅳ号异常带具较好的找矿前景,为项目续作的重点靶区,同时认识到主成矿元素Sb和Au属于不同期地质作用叠加的结果。

The Dongshanwu area lies in northeastern Jiangnan orogenic belt, where stream anomalies of Au-As-Sb were delineated in 1989, and 2 603 soil samples were collected in 2011 for analysis of Au, Ag, Cu, Pb, Zn, As, Sb, Bi, W and Mo. According to math-ematical geological analysis and single element anomaly evaluation, the authors hold that they belong to normal distribution except As. Au has a close affinity with As, Sb has a close affinity with Ag and Mo, and Ag and Mo have high background values. The concentra-tion Clarke values and variation coefficients of Sb indicate that Sb were involved in mineralization. Drilling has already revealed Sb ore- body ,suggesting that the area has a good potential of Sb. Au anomalies are in accord with As anomalies, and Au is a concentrated ele-ment and has the biggest variation coefficient, suggesting that Au is unevenly distributed, Au mineral alteration is in accord with the tectonic belt, and Au is positively related to silicification. Through soil geochemical survey, 4 synthetic anomaly belts were delineated in Dongshanwu area, among which, I , E and W have better prospecting potential. In addition, the authors detected that Sb and Au ores resulted from the superimposition of geological activities of different epochs.