地球学报2012，Vol.33Issue(4)：459-470,12.DOI:10.3975/cagsb.2012.04.07
西藏雄村斑岩型铜金矿集区Ⅰ号矿体的硫、铅同位素特征及其对成矿物质来源的指示
Sulfur and Lead Isotope Characteristics of No.Ⅰ Ore Body in the Xiongcun Porphyry Copper-Gold Ore Concentration Area of Tibet:Implications for the Source of Metals in the Ore Deposit
摘要
Abstract
The Xiongcun porphyry copper-gold ore concentration area, one of the large-size metallogenic areas discovered along the Gangdise porphyry copper belt, occurs in an island arc environment associated with northward intra-oceanic subduction of Neo-Tethys oceanic crust. The ore-forming age of the Xiongcun porphyry copper-gold ore concentration area is middle Jurassic. It is located in the middle of the southern margin of the Gangdise orogenic belt, and its south margin is Shigatse forearc basin. The latest exploration data indicate that there are several potential mineralization-alteration areas and three large-size copper-gold ore bodies (No. I, II and Ⅲ) in the Xiongcun porphyry copper-gold ore concentration area. In this paper, Xiongcun No. I ore body was chosen as the research object. According to sulfur and lead isotope composition of ore-baring porphyry, tuff and main sulfides of the ore, the authors have reached the following two conclusions: 1) Sulfur isotopic compositions vary in a narrow range of δ34S values from -3.5‰ to +2.7‰ (-1.07‰ on average) and are close to zero, indicating a mantle sulfur signature. 2) They have uniform Pb isotope compositions with low content of radiogenic Pb. The 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios vary in the ranges of 18.104-18.432, 15.473-15.533 and 37.918-38.3072, respectively. They are located in the transition zone of mantle Pb and orogen Pb but are closer to the former, reflecting a mixing between the mantle material and minor crust material. Through a comparative study of sulfur and lead isotopes of porphyry copper deposits of the island arc environment (e.g., Xiongcun No. I ore body) and those of the collisional orogenic environment in the Gangdise porphyry copper belt, the authors found that they have similar metal sources, but porphyry copper deposits of the island arc environment have experienced weak contamination of crust materials, whereas porphyry copper deposits of the coilisional orogenic environment have experienced strong contamination of crust materials.关键词
硫同位素/铅同位素/雄村/斑岩铜矿床/西藏冈底斯带Key words
sulfur isotope/ lead isotope/ Xiongcun/ porphyry copper-gold deposit/ Gangdise belt in Tibet分类
天文与地球科学引用本文复制引用
郎兴海,唐菊兴,李志军,黄勇,丁枫,王成辉,张丽,周云..西藏雄村斑岩型铜金矿集区Ⅰ号矿体的硫、铅同位素特征及其对成矿物质来源的指示[J].地球学报,2012,33(4):459-470,12.基金项目
本文由国家自然科学基金(编号:41172077)、国家973项目(编号:2011CB403103)、西藏天圆矿业资源开发有限公司项目(编号:2006G-07)和中国地质调查局地调项目"西藏大型矿床成矿专属性研究"(编号:资[2012]03-002-055)联合资助. （编号:41172077）
