闽中梅仙矿集区丁家山铅锌矿床成矿时代厘定及成矿物质来源:来自闪锌矿Rb-Sr同位素的证据  

Determination of mineralization age and ore-forming materials of the Dingjiashan Pb-Zn deposit in the Meixian ore concentration area,the central Fujian Province:evidence from the sphalerite Rb-Sr isotope

作　　者：肖晓牛 邢波 余新明 葛明慧 秦新龙 刘荣芳 杜壮志 XIAO Xiaoniu;XING Bo;YU Xinming;GE Minghui;QIN Xinlong;LIU Rongfang;DU Zhuangzhi(Jiangsu Provincial Geological Bureau,Nanjing 210007,Jiangsu,China;School of Earth Sciences and Engineering,Nanjing University,Nanjing 210093,Jiangsu,China;Fujian Jindong Mining Co.,Ltd.,Sanming 365101,Fujian,China;Zijin School of Geology and Mining,Fuzhou University,Fuzhou 350108,Fujian,China)

机构地区：[1]江苏省地质局,江苏南京210007 [2]南京大学地球科学与工程学院,江苏南京210093 [3]福建金东矿业股份有限公司,福建三明365101 [4]福州大学紫金地质与矿业学院,福建福州350108

出　　处：《地质通报》2022年第11期2026-2034,共9页Geological Bulletin of China

基　　金：福建省自然科学基金项目《闽中梅仙地区花岗岩及其铅锌钼多金属成矿系列研究》(编号:2018J01143);江苏省博士后基金、国家自然科学基金项目《云南播卡晚元古代岩浆作用与成矿效应:一种可能的IOCG模式》(批准号:41402077)。

摘　　要：丁家山铅锌矿床位于闽中梅仙矿集区西南部,矿体多呈层状、似层状和透镜状,产于中—新元古界马面山群龙北溪组的绿片岩和大理岩中。为查明该矿床的成矿时代,对该矿床中的主要矿石矿物闪锌矿开展了Rb-Sr同位素测年。8件闪锌矿样品构成的等时线年龄为143.1±3.2 Ma(MSWD=1.7),表明该矿床形成于燕山中期晚侏罗世。闪锌矿的锶同位素(初始比值为0.71434±0.00036)及前人的硫、铅同位素研究成果共同指示,丁家山矿床的成矿物质可能主要来源于下地壳的深源岩浆。综合分析认为,丁家山矿床形成于古太平洋板块向欧亚大陆板块俯冲-消减后的伸展引张环境背景下,是晚侏罗世到早白垩世期间的花岗岩体与中—新元古界的大理岩经接触交代后的矽卡岩型矿床。作为梅仙矿集区的典型铅锌矿床,丁家山矿床的成矿时代对区内其他铅锌矿床的成矿时代具有一定约束意义。The Dingjiashan Pb-Zn deposit is located in the southwest of the Meixian ore concentration area in the central Fujian province.The Pb-Zn orebodies are predominantly hosted in the Meso-Neoproterozoic greenschist and marble of the Longbeixi Formation belonging to the Mamianshan Group in the layer,layer-like,and lenticular shape.In this contribution,the Rb-Sr dating for sphalerite was carried out in order to determine the mineralization age of the deposit.The isochron age of 8 sphalerite samples is 143.1±3.2 Ma(MSWD=1.7),indicating that the deposit was formed in the Late Jurassic.The initial 87 Sr/86 Sr ratio of the sphalerite(0.71434±0.00036)and the previous S-Pb isotope studies indicate that the ore-forming materials at Dingjiashan may mainly source from deep-seated magma in the lower crust.Base on the above analyses,it is considered that the Dingjiashan deposit was formed under the condition of the extensional environment caused by the subduction of the ancient Pacific plate to the Eurasian continental plate,and was the product of contact metasomatism between the Late Jurassic to Early Cretaceous granite intrusions and the Meso-Neoproterozoic marble.The mineralization age of the Dingjiashan deposit has a constraint on that of the other Pb-Zn deposits from the Meixian ore concentration area.

关 键 词：丁家山铅锌矿床 RB-SR同位素 成矿时代 梅仙矿集区 闽中地区 

分 类 号：P618.42[天文地球—矿床学] P618.43[天文地球—地质学]