广西大厂锡多金属矿田成矿物质来源的示踪  

The sources of ore-forming materials for the Dachang tin polymetallic ore field,Guangxi,China

作　　者：李乾坤 周闯 LI Qiankun;ZHOU Chuang(State Key Laboratory of Ore Deposit Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang Guizhou 550081,China;University of the Chinese Academy of Sciences,Beijing 100049,China;School of Earth Resources,China University of Geosciences(Wuhan),Wuhan Hubei 430074,China)

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550081 [2]中国科学院大学,北京100049 [3]中国地质大学(武汉)资源学院,湖北武汉430074

出　　处：《矿物学报》2024年第2期261-272,共12页Acta Mineralogica Sinica

摘　　要：广西大厂锡多金属矿田目前是世界上最大的锡多金属产地之一。为了探讨大厂矿田中铜坑-长坡矿床和高峰矿床成矿物质来源,本研究对这2个矿床主要成矿阶段硫化物的S同位素及主、微量元素进行了分析。研究结果表明,铜坑-长坡硫化物δ^(34)S范围为-9.2‰~0.6‰(均值为-3.3‰),总体呈塔式集中分布于-4‰~-1‰,指示S主要为岩浆和地层混合来源。高峰矿床硫化物δ^(34)S范围为4.2‰~12.1‰(均值为9.7‰),集中分布于10‰~12‰,由于硫酸盐热化学还原作用导致的硫同位素分馏有限,因此,本文推测高峰矿床硫主要来源于海水硫酸盐的还原和岩浆硫的混合。闪锌矿的Zn/Cd值表明,铜坑-长坡和高峰矿床的Zn/Cd值极为相似,并且与矿田地层和大厂花岗岩Zn/Cd值存在重叠,表明铜坑-长坡和高峰矿床硫化物成矿物质(S和金属)主要来源于泥盆系地层和岩浆岩。The Dachang tin polymetallic orefield in Guangxi Zhuang Autonomous Region is currently one of the largest production base of tin and polymetals in the world.In order to decipher the source of ore-forming materials of the Tongkeng-Changpo and Gaofeng deposits in the Dachang orefield,S isotopes and major and trace elements of sulfides of main mineralization stages from those deposits have been analyzed in this study.The results show that theδ^(34)S values of sulfides in the Tongkeng-Changpo deposit range from-9.2‰to 0.6‰(an average of-3.3‰),with a typical normal distribution varying mainly from-4‰to-1‰,indicating that S in this deposit was sourced from the mixing of magmatic and stratigraphic sulfurs.Theδ^(34)S values of sulfides of the Gaofeng deposit range from 4.2‰to 12.1‰(an average of 9.7‰),mainly vary from 10‰to 12‰.These values are different from those of sulfate samples in hosting strata.As the sulfur isotope fractionation caused by the thermochemical sulfate reduction is limited,we proposed that the sulfur in the Gaofeng deposit was mainly sourced from the mixing of sulfur from the reduction of seawater sulfate and magmatic sulfur.In addition,Zn/Cd ratios of spahlerites from the Tongkeng-Changpo and Gaofeng deposits are very similar,and they are partially overlapped with those of the Dachang granite and regional strata,indicating that the ore-forming materials for sulfides of the Tongkeng-Changpo and Gaofeng deposits were mainly derived from the Devonian strata and magma of the Dachang granite.

关 键 词：大厂矿田 硫同位素 微量元素 成矿物质来源 

分 类 号：P618.4[天文地球—矿床学] P595[天文地球—地质学]