摘要:
浙江下铜山地处钦杭成矿带东段,在岩体接触带发现有钨钼矿化现象. 2012年在区内进行1:5 000土壤地球化学测量,发现区内板桥山组碳酸盐岩地层中土壤铅锌异常较高,且在大区域中,板桥山组地层是铅锌成矿的重点层位,因而将此处铅锌异常视为成矿重点异常. 但考虑到铅锌异常浓集中心并未完全与岩体套合,而是在岩体南边碳酸盐岩地层内,且实地考察时地表未见矿化现象,局部可见不连续氧化帽,推测此处铅锌异常为次生富集成因. 为了对异常成因进行进一步研究,选取探槽中岩石样和土壤样进行铅锌含量比较,发现土壤中铅锌含量明显高于岩石;而选取剖面土壤样进行铅锌与铁锰含量对比,也发现铅锌含量变化趋势与铁锰具有较好的一致性. 综合分析后将该区的铅锌异常归为碳酸盐岩风化导致的铅锌次生富集产生的假异常,不具成矿意义.
Abstract:
The Xiatong Mountain in Zhejiang Province is in the eastern part of the Qin-Hang metallogenic belt, where tungsten molybde-num mineralization phenomena have been found in the contact zone of the rock mass. According to the 1:5 000 soil measurements in 2012, lead and zinc content is very high in carbonate formation which belongs to Banqiao Mountain strata, which are the key strata of lead and zinc deposits in the region. The results obtained show that lead and zinc anomalies in this area could be considered as the key anomalies related to mineralization. In consideration of the facts that the anomaly concentration areas of lead and zinc are distributed in the south of carbonate formation instead of having to do with the rock mass, mineralization phenomena at the surface are not obvious, and discontinu-ous oxidation cap could be observed, it is inferred that the lead and zinc anomalies might be caused by secondary enrichment. In order to make a further study of the genesis of the anomaly, the authors chose exploratory trench rock and soil samples to make a comparative study of lead and zinc values. It is found that the content of lead and zinc in soil is significantly higher than that in the rock. Then the authors chose three section lines to conduct a soil element content research, and the results show that the distribution of Pb, Zn and Fe, Mn has much to do with the concentration-dilution relationship. On such a basis, it is concluded that the Pb, Zn anomalies here have no minerali-zation significance, and they are false anomalies caused by the carbonate weathering secondary enrichment.
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