桂中两江Cu矿床的地质和S-Pb同位素研究  

Geology and Sulfur and Lead Isotopic Geochemistry of Liangjiang Cu Deposit, Central Guangxi Province, Southern China

作　　者：蔡伊[1,2,3] 李艳萍 张乾[1] 王大鹏[1] 李开文 张永斌[1,2] 

机构地区：[1]中国科学院地球化学研究所矿床地球化学国家重点实验室,贵州贵阳550002 [2]中国科学院大学,北京100049 [3]贵州师范大学喀斯特生态文明研究中心 [4]河南地质调查研究院,河南郑州450001

出　　处：《矿物学报》2016年第1期103-110,共8页Acta Mineralogica Sinica

基　　金：矿床地球化学国家重点实验室"十二五"项目群(SKLODG-ZY125-04);国家自然科学基金面上项目(批准号:41372105)

摘　　要：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δ^34SCDT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, located in the central Guangxi province, southern China, is a typical quartz vein type mineralization. To clarify its ore genesis, an investigation of the geological feature and sulfur and lead isotope is carried out on this deposit. Sulfur isotopic compositions of sulfides have a relatively uniform δ^34SCDT value ranging from-1.22‰ to 0.96‰, suggesting a magmatic hydrothermal origin. Ore sulfides from the deposit are enriched in radioactive lead and range in ^208Pb/v204 Pb,^207Pb/^204 Pb and 206Pb/204 Pb ratios from 38.698 to 39.817, 15.773 to 15.879 and 18.307 to 19.232, with the mean values of 39.151, 15.809 and 18.603, respectively. In comparison, they are obviously different from that of Cambrian and Devonian strata and Caledonian magmatic rocks, but consistent with that of the Late Cretaceous magmatic rocks, hinting to that Pb and ore-forming metals are probably derived from the Late Cretaceous magmatism. Field and geochemical evidences, i.e., cross-cutting of ore bodies and magmatic origin of ore-forming materials, indicate that the Cu deposit possibly formed during Late Cretaceous. Regional mineralized features including the Gejiu, Bainiuchang, Dulong and Dachang ore districts suggest that abundant skarn and quartz ore bodies should be probably concealed under cover, indicating a vast prospecting potential at depth in the Liangjiang Cu deposit.

关 键 词：加里东期 成矿作用 地球化学 燕山期 大明山 

分 类 号：P611.1[天文地球—矿床学] P595[天文地球—地质学]