论文部分内容阅读
湖南宝山Cu-Mo-Pb-Zn-Ag多金属矿床规模大、矿种多、分带明显,是南岭有色金属成矿带的代表性矿床之一。本文对该矿床的硫同位素组成进行了较系统的研究,以探讨该矿床成矿物质的来源。研究表明,硫化物硫同位素组成具有δ34S黄铁矿>δ34S闪锌矿>δ34S方铅矿特征,说明成矿流体中硫已达到分馏平衡;矿床硫化物的硫同位素组成均为较低正值,变化范围很窄,δ34S值主要集中在1.50‰~4.50‰之间,峰值在3‰左右,明显低于研究区石炭系碳酸盐岩硫同位素δ34S值(17.8‰~22.6‰),具岩浆硫特征,暗示成矿流体中硫主要来源于燕山期花岗闪长斑岩有关的岩浆分异,地层硫贡献较少。此外,不同围岩的矿体,硫化物δ34S值基本相同,围绕花岗闪长斑岩体δ34S值没有分带现象,表明硫的来源具有一致性。因此,有理由认为,赋存于下石炭统梓门桥组白云岩、测水组砂页岩和石凳子组灰岩中的Pb-Zn多金属矿化具有相同成因联系,它们应为同一岩浆-热液系统演化的产物。
The Baoshan Cu-Mo-Pb-Zn-Ag polymetallic deposit in Hunan is large in scale with many mines and obvious zonation. It is one of the representative deposits of the Nanling non-ferrous metallogenic belt. This paper systematically studies the sulfur isotopic composition of this deposit to explore the source of ore-forming materials in this deposit. The results show that the sulfur and sulfur isotopic compositions have the features of δ34S pyrite> δ34S sphalerite> δ34S galena, indicating that the sulfur in the ore-forming fluid has reached the equilibrium of fractionation. The sulfur isotopic compositions of the sulfide minerals in the ore deposits are both lower positive values, The δ34S value is mainly between 1.50 ‰ ~ 4.50 ‰ and the peak value is about 3 ‰, which is significantly lower than the δ34S value of sulfur isotopes (17.8 ‰ ~ 22.6 ‰) of Carboniferous carbonate rocks in the study area. It is suggested that the sulfur in the ore-forming fluid is mainly derived from the magmatic differentiation related to the Yanshanian granodiororphic porphyry and the contribution of formation sulfur is less. In addition, δ34S values of sulphides are basically the same in the ore bodies and sulphides of different surrounding rocks. There is no zoning phenomenon around the δ34S value of granodiorite porphyry bodies, indicating that the sources of sulfur are consistent. Therefore, it is reasonable to assume that the Pb-Zn polymetallic mineralization occurring in limestone of the Lower Carboniferous Zimenqian Formation dolomite, water logging sandstone and stool group has the same genetic association, they should be the same magma - The product of hydrothermal system evolution.