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两江Cu矿床为一个位于广西中部的石英脉型矿床。为了查明矿床成因,笔者对该矿床分别进行了矿床地质和S-Pb同位素研究。结果表明,矿石硫化物S同位素的δ34SCDT介于-1.22~0.96‰之间,呈塔式分布,暗示矿石S为岩浆或深部热液起源。矿石Pb同位素的208Pb/204Pb、207Pb/204Pb和206Pb/204Pb的比值分别介于38.698~39.817、15.773~15.879和18.307~19.232之间,平均值分别为39.151、15.809和18.307。对比研究表明,矿石与地层(寒武系和泥盆系)砂页岩和加里东期岩浆岩完全不同的Pb同位素组成,而与晚白垩世岩浆岩(包括昆仑关黑云母花岗岩)具有较为相近分布范围。因此,该矿床的矿石Pb及其成矿金属物质最有可能起源于晚白垩世岩浆作用。结合矿体交截关系和成矿物质来源研究,笔者推测该矿床最有可能形成于晚白垩世。由于含矿石英斑岩为加里东期岩浆作用的产物,因此,在矿区深部存在与成矿作用有成生关系的隐伏岩体,很可能为昆仑关黑云母花岗岩岩基向西北方向延伸部分。区域矿化特征对比表明,大明山W-Cu多金属成矿带深部可能存在矽卡岩型矿化,并预示着巨大的找矿潜力。
The Liangjiang Cu deposit is a quartz vein type deposit located in central Guangxi. In order to find out the genesis of the deposit, the authors carried out a study on the geology and S-Pb isotope of the deposit respectively. The results show that δ34SCDT of S isotopes of ore ores ranges from -1.22 to 0.96 ‰, showing tower distribution, indicating that ore S is the origin of magma or deep hydrothermal fluids. The ratios of 208Pb / 204Pb, 207Pb / 204Pb and 206Pb / 204Pb of ore Pb isotope ranged from 38.698 to 39.817, from 15.773 to 15.879 and from 18.307 to 19.232, with the average values of 39.151, 15.809 and 18.307, respectively. Comparative studies have shown that the ore has completely different Pb isotopic compositions from the sandstone and Cambrian magmatic rocks in the stratigraphy (Cambrian and Devonian), and is quite similar to Late Cretaceous magmatic rocks (including the Kunlunuan biotite granite) distribution area. Therefore, the ore Pb and its metallogenic materials in this deposit are most likely to originate from Late Cretaceous magmatism. According to the relationship between ore body intercept and the source of metallogenic materials, the author speculates that the deposit is most likely to form in the Late Cretaceous. Because the orebearing quartz porphyry is the product of Caledonian magmatism, there exists a concealed rock mass that has a relationship with mineralization in the deep part of the ore area, which is likely to be the northwest extension of the Kunlundependent biotite granite basement. A comparison of regional mineralization shows that there may be skarn-type mineralization in the deep part of the D-ming W-Cu polymetallic metallogenic belt, which indicates a great prospecting potential.