延边天宝山矿集区晚古生代岩浆-热液成矿的年代学证据——以新兴铅锌(银)矿床为例  

Geochronologic evidence of Late Paleozoic magmatic-hydrothermal mineralization in Tianbaoshan metallogenic region,Yanbian area: A case study of the Xinxing leadzinc (silver) deposit

作　　者：杨群[1] 任云生[1,2] 孙振明[1] 郝宇杰[1,2] 张博 孙新浩 陆思宇 YANG Qun;REN YunSheng;SUN ZhenMing;HAO YuJiel＇;ZHANG Bo;SUN XinHao;LU SiYu(College of Earth Sciences,Jilin University,Changchun 130061,China;Key Laboratory of Mineral Resources Evaluation in Northeast Asia,Ministry of Land and Resources of China,Changchun 130061,China;Hanfeng Mining Co.Ltd,Longjing 133400,China)

机构地区：[1]吉林大学地球科学学院,长春130061 [2]国土资源部东北亚矿产资源评价重点实验室,长春130061 [3]瀚丰矿业有限公司,龙井133400

出　　处：《岩石学报》2018年第10期3153-3166,共14页Acta Petrologica Sinica

基　　金：国家重点研发计划项目(2017YFC0601304);国家重点基础研究发展规划("973计划")项目(2013CB429802)联合资助

摘　　要：延边天宝山矿集区已发现矽卡岩型铅锌铜矿床(立山和选厂后山)、隐爆角砾岩型铅锌(银)矿床(新兴)、沉积变质-热液改造型铜铅锌矿床(东风南山)和斑岩型钼矿床(东风北山)等四种成因类型、十余个矿床(点)。为确定矿集区内多金属成矿作用的期次,在已有工作基础上,本文首次采用LA-ICP-MS锆石U-Pb法和金属硫化物Rb-Sr法,对新兴铅锌(银)矿床开展了同位素年代学研究。结果表明,与角砾岩型铅锌(银)矿化密切相关的新兴花岗闪长岩的16个锆石测点的206Pb/238U年龄加权平均值为261. 1±3. 5Ma(MSWD=0. 46),角砾岩型矿石6件金属硫化物的Rb-Sr等时线年龄为259±3Ma(MSWD=1. 05),锶同位素初始值ISr=0. 71359,表明新兴矿床的成岩成矿时代为中二叠世晚期。结合矿集区内其它矿床的同位素测年资料分析认为,天宝山矿集区至少发生过晚古生代和早中生代两期岩浆-热液成矿事件,在中-晚二叠世形成了立山、选厂后山和新兴等多金属矿床,在早侏罗世则形成了东风北山斑岩型钼矿床。新兴矿床6件金属硫化物的Rb、Sr含量分别介于0. 1238×10-6～0. 7536×10-6和0. 3786×10-6～3. 247×10-6之间,初始Sr同位素比值(87Sr/86Sr)i介于0. 71350～0. 71371之间,均值为0. 71361,表明成矿物质以壳源为主,并有少量幔源物质的加入。综合研究表明,在中-晚二叠世(255～265Ma),受古亚洲洋俯冲作用的影响,天宝山矿集区发生了深源岩浆侵入,引发地壳物质同熔,形成富含Cu、Pb、Zn、Ag等金属元素的花岗闪长质岩浆,沿着构造裂隙上升至地壳浅部,侵位形成了矿集区内的立山、新兴、东风北山等多个晚古生代成矿(含矿)中酸性岩体。在花岗闪长岩与大理岩接触带附近,通过含矿热液交代作用,形成了立山、选厂后山等矽卡岩型铅锌铜矿床;随着岩浆期后热液在岩浆房顶部的不断聚集,挥发分的增加,当内压大于上部围岩压力时,发生隐爆�F0ur genetic types and over ten deposits（ mineral occurrences） have been discovered in the Tianbaoshan metallogenic region in Yanbian area,including Lishan and Xuanchanghoushan skarn-type lead-zinc-copper deposits,Xinxing cryptoexplosive breccia-type lead-zinc（ silver） deposit,Dongfengnanshan sedimentary-hydrothermal copper-lead-zinc deposit and Dongfengbeishan porphyry molybdenum deposit. To better understand metallogenic sequence of polymetallic mineralization in Tianbaoshan region,sulfide Rb-Sr dating and LA-ICP-MS zircon U-Pb dating of intrusion associated with polymetallic mineralization in the Xinxing lead-zinc（ silver） deposit have been carried out. LA-ICP-MS zircon U-Pb dating of 16 analytical spots from the metallogenic granodiorite obtains the weighted mean206 Pb/238 U age of 261. 1 ± 3. 5 Ma（ MSWD = 0. 46）,and Rb-Sr dating of six sulfide samples from breccia-type ore yields an isochron age of 259 ± 3 Ma（ MSWD = 1. 05）,with initial Sr isotopic composition ISr= 0. 71359,implying the close temporal and genetic link between magmatism and mineralization. These consistent isotopes dating results show that both the emplacement of granodiorite and associated lead-zinc mineralization can be constrained to the end of middle Permian. Based on isotope dating results in this paper and existing isotope dating data,it can be concluded that Lishan,Xuanchanghoushan and Xinxing polymetallic deposits formed in Middle-Late Permian（ 255 - 265 Ma）,and Dongfengbeishan porphyry molybdenum deposit formed in the Early Jurassic（ -192 Ma）. The Rb and Sr contents in six sulfide mineral samples range from 0. 1238 × 10-6 to 0. 7536 × 10-6,0. 3786 × 10-6 to 3. 247× 10-6,respectively,and the initial Sr isotope ratios（87 Sr/86 Sr）irange from 0. 71350 to 0. 71371,with an average of 0. 71361. Rb and Sr contents indicate that metallogenic materials of the Xinxing lead-zinc（ silver） deposit mainly derived from the crust,and mixed with small amount of mantle material. Comprehensive studies show that

关 键 词：硫化物Rb-Sr法测年 LA-ICP-MS锆石U-Pb法测年 成矿物质来源 天宝山矿集区 新兴铅锌(银)矿床 

分 类 号：P618.2[天文地球—矿床学] P597.3[天文地球—地质学]