吉林延边红太平铜多金属矿床脉型矿化的成矿时代与构造背景  

Age and tectonic setting of vein-type mineralization of Hongtaiping copper polymetallic deposit in Yanbian area, Jilin Province, NE China

作　　者：侯鹤楠[1] 任云生[1,2] 陆思宇 郝宇杰 杨群[1] HOU HeNan;REN YunSheng;LU SiYu;HAO YuJie;YANG Qun(College of Earth Sciences,Jilin University,Changchun 130061,China;School of Earth Science,Institute of Disaster Prevention,Sanhe 065201,China;Key Laboratory of Mineral Resources Evaluation of Northeast Asia,Ministry of Natural and Resources of China,Changchun 130061,China)

机构地区：[1]吉林大学地球科学学院,长春130061 [2]防灾科技学院地球科学学院,三河065201 [3]自然资源部东北亚矿产资源评价重点实验室,长春130061

出　　处：《岩石学报》2020年第3期820-836,共17页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(41772062);国家重点研发计划项目(2017YFC0601304);自然资源部东北亚矿产资源评价重点实验室开放基金课题(DBY-KF-19-01)联合资助。

摘　　要：吉林延边红太平铜多金属矿床位于兴蒙造山带东段,区内发育产于晚古生代火山沉积岩系中的层状铜多金属矿体和受岩体及构造控制的脉状铅锌矿体。为了确定脉型铅锌矿化的成矿时代与构造背景,本文对与脉状铅锌矿体相关的英安岩开展了LA-ICP-MS锆石U-Pb定年及岩石地球化学研究,并对脉状铅锌矿体中金属硫化物开展了Rb-Sr同位素定年。结果表明,英安岩中28个锆石测点的206Pb/238U加权平均年龄为204.1±2.0Ma(MSWD=0.24),脉状铅锌矿石中4件金属硫化物的Rb-Sr等时线年龄为206.8±9.0Ma(MSWD=2.0),二者在误差范围内基本一致,表明红太平矿床脉型铅锌矿化的成矿时代为晚三叠世末期。英安岩的稀土元素配分模式呈明显的轻稀土元素(LREEs)富集,轻重稀土分馏明显[(La/Yb)N=7.59~8.28],存在弱的Eu异常(δEu=0.65~0.68);微量元素以富集大离子亲石元素(LILEs:Rb、Ba和K)和不相容元素(U、Th),亏损高场强元素(HFSEs:Nb、Ta、P和Ti)为特征,表明原始岩浆应为壳-幔混源;脉状铅锌矿体中4件金属硫化物初始Sr同位素比值(87Sr/86Sr)i为0.705954~0.707101(均值0.706390),表明脉型铅锌矿化与壳-幔混源的岩浆作用密切相关。根据Rb-(Yb+Ta)及La/Yb-Th/Yb图解判别结果,结合区域构造演化分析,认为红太平矿区英安岩及相关的脉型铅锌矿化形成于活动大陆边缘的构造环境,与晚三叠世-早侏罗世(T3-J1)古太平洋板块向欧亚板块的俯冲作用密切相关。The Hongtaiping copper polymetallic deposit in Yanbian area,Jilin Province of Northeast China,is tectonically located in the east margin of the Xing'an-Mongolian Orogenic Belt(XMOB).Two types of ore bodies have been identified in this deposit,including the stratiform Cu polymetallic ore body hosted by the Late Paleozoic volcanic sedimentary rocks,and the vein-type Pb-Zn ore body controlled by the intrusion and structures.To determine the mineralization age and tectonic setting of the vein-type ore body,LA-ICP-MS zircon U-Pb dating and petrogeochemical studies were carried out on the dacite associated with the vein-type mineralization,and Rb-Sr isotope dating of metal sulfides in the vein-type ore body was conducted.The isotope dating results indicate that the 206Pb/238U weighted mean age of the 28 zircon grains in the dacite is 204.1±2.0Ma(MSWD=0.24),and the Rb-Sr isochron age of 4 metal sulfide samples is 206.8±9.0Ma(MSWD=2.0).Two groups of ages are nearly consistent and indicate that the vein-type Pb-Zn mineralization was formed at the end of Late Triassic Period.The dacite associated with the vein-type mineralization is characterized by the enrichment of light rare earth elements(LREEs),and fractional distillation of light and heavy rare earth elements[(La/Yb)N=7.59~8.28],as well as weak Eu anomalies(δEu=0.65~0.68).Trace elements in the dacite samples are characterized by the enrichment of large ion lithophile elements(LILEs:Rb,Ba and K)and incompatible elements(U and Th),the depletion of high field strength elements(HFSEs:Nb,Ta,P and Ti),indicating that the primary magma is originated from the crust-mantle mixed materials.The initial Sr isotope ratio(87Sr/86Sr)i of 4 metal sulfide samples from the vein-type ore body is 0.705954 to 0.707101(averaged at 0.706390),implying that the ore-forming materials are derived from the crust-mantle mixed source.In the Rb-(Y+Nb)and La/Yb-Th/Yb diagrams,the tectonic environment of the dacite can be determined as the active continental margin.The dacite and vein-type Pb-Zn

关 键 词：LA-ICP-MS锆石U-PB定年 硫化物Rb-Sr定年 脉状铅锌矿化 红太平铜多金属矿床 吉林延边 

分 类 号：P588.142[天文地球—岩石学] P597.3[天文地球—地质学]