陕西陈家坝铜铅锌多金属矿床C、H、O、S、Sr同位素地球化学示踪  

C,H,O,S,Sr isotopic geochemistry of Chenjiaba Cu-Pb-Zn polymetallic deposit,Shaanxi Province

作　　者：丁坤[1] 王瑞廷 秦西社[2] 梁婷 杨秀清[1] 栾燕 郑崔勇[3] 樊新祥 DING Kun;WANG RuiTing;QIN XiShe;LIANG Ting;YANG XiuQing;LUAN Yan;ZHENG CuiYong;FAN XinXiang(School of Earth Sciences and Resources, Chang'an University, Xi'an 710054, Shaanxi, China;Northwest Nonferrous Geological Mining Group Co., Ltd., Xi'an 710054,Shaanxi, China;Northwest Nonferrous No.711 Geological Party of Hanzhong, Hanzhong 723000, Shaanxi, China;Fourth Institute of Geological and Mineral Exploration, Gansu Provincial Bureau of Geological and Mineral Exploration and Development, Jiuquan 735000, Gansu, China)

机构地区：[1]长安大学地球科学与资源学院,陕西西安710054 [2]西北有色地质矿业集团有限公司,陕西西安710054 [3]汉中西北有色七一一总队有限公司,陕西汉中723000 [4]甘肃省地质矿产勘查开发局第四地质矿产勘查院,甘肃酒泉735000

出　　处：《矿床地质》2019年第2期355-366,共12页Mineral Deposits

基　　金：国家自然科学基金青年科学基金项目(编号:41603040);西北有色地质矿业集团有限公司博士后科研项目;中国地质调查局项目(编号:1212011220869)联合资助

摘　　要：陈家坝铜铅锌多金属矿床为近年来在陕西勉(县)-略(阳)-宁(强)铜金镍矿化集中区新发现的铜铅锌多金属矿床。为了查明陈家坝矿床成矿物质来源,笔者开展了系统的C、H、O、S和Sr同位素地球化学研究。结果表明,陈家坝矿区的围岩的δ^(13)CPDB值范围-0.93‰～1.44‰,平均值为0.35‰,δ^(18)OV-SMOW值范围14.14‰～27.49‰,平均22.1‰,为沉积成因海相碳酸盐岩。脉石矿物白云石的δ^(13)CPDB范围在-0.53‰～-0.89‰,δ^(18)OV-SMOW值范围12.12‰～13.23‰,指示成矿流体中的CO_2主要来自岩浆水,少量CO_2来源于围岩海相碳酸盐岩的溶解作用。成矿流体中δD值范围-91‰～-72‰,δ^(18)OH矿流体以岩浆流体为主。成矿流体与围2岩的水-岩反应是导致该区铜铅锌2矿床中白云石和黄铜矿、闪锌矿和方铅矿矿物沉淀结晶的主要机制。矿石金属硫化物δ34S值范围4.88‰～8.90‰,平均值为7.37‰,介于岩浆硫与海水硫之间,且与矿集区内典型的徐家沟铜矿床矿石矿物δ34S变化区间重叠,表明硫主要来自于岩浆硫,部分硫来自海水硫酸盐。矿石中黄铁矿的初始锶同位素比值87Sr/86Sr比值为0.72,高于赋矿围岩锶同位素比值,接近大陆地壳的87Sr/86Sr比值(0.719),指示了成矿流体流经了雪花太坪组地层,并与其中具有高87Sr/86Sr比值的白云岩进行水岩反应及同位素交换。The Chenjiaba Cu-Pb-Zn polymetallic deposit in Shaanxi Province, located in Mian(xian)-Lue(yang)-Ning(qiang) Cu-Au-Ni ore concentration area, is a newly discovered deposit. In this paper, C, H, O, S and Sr isotopic geochemistry was systematically studied in order to understand comprehensively the source of ore-forming materials. The analytical results show that13 CPDBand18 OV-SMOWvalues of surrounding rocks are between-0.93‰ and1.44‰ and 14.14‰ and 27.49‰, respectively, suggesting that the surrounding rocks were derived from marine carbonate dissolution. the δ13 CPDBvalues of gangue dolomite samples are in the range of-0.53‰^-0.89‰, and the18 OV-SMOWvalues in the range of 12.12‰~13.23‰. In the Chenjiaba Cu-Pb-Zn polymetallic deposit, the CO2 in the ore-forming fluid was mainly derived from magmatic water, with a small amount from marine carbonate dissolution. The δDVSMOWof the quartz fluid inclusions is between-91‰ and-72‰, the δ18 OH2 Ois between 6.7‰and 9.4‰, and the δD-δ18 OH2 Odiagram shows that the main source of ore-forming fluid was magmatic water. Water-rock reaction between ore-forming fluid and surrounding rock was the main mechanism resulting in the precipitation and crystallization of dolomite, sphalerite, chalcopyrite and galena in Chenjiaba Cu-Pb-Zn polymetallic deposit, Shaanxi. Sulfur isotopic compositions(δ34 S from 4.88‰ to 8.90‰, 7.37 ‰ on average) are both magmatic sulfur and seawater sulfur, consistent with the data of the typical Xujiagou Cu deposit in this area. The results indicate that sulfur sources were mainly sourced from magmatic sulfur with the addition of small amounts of seawater sulfur. The87 Sr/86 Sr ratio of pyrite in the ore is 0.7187, higher than87 Sr/86 Sr ratio(0.7083) of surrounding rock and similar to the ratio of continental crust(0.719), suggesting that ore-forming fluid probably migrated through the formation of Xuehuataiping Formation, and experienced water-rock reaction and isotope exchange between the ore fluid and the dolomite whi

关 键 词：地球化学 碳、氢、氧、硫、锶同位素组成 成矿物质来源 陈家坝Cu-Pb-Zn多金属矿床 陕西 

分 类 号：P618.51[天文地球—矿床学]