闽中裂谷带梅仙铅锌矿区花岗斑岩的LA-ICP-MS锆石U-Pb年龄、成因及成矿效应  

LA-ICP-MS Zircon U-Pb Age,Petrogenesis and Metallogenic Effect for Porphyry Granites from the Meixian Pb-Zn Deposit in the Central Fujian Rift,Southeast China

作　　者：孙洪涛[1,2] 王秋玲[1,2] 雷如雄[3] 陈世忠[4] 陈刚[4] 吴昌志[1] 

机构地区：[1]南京大学地球科学与工程学院,南京210093 [2]江苏省有色金属华东地质勘查局,南京210007 [3]长安大学地球科学与资源学院,西安710054 [4]中国地质调查局南京地质调查中心,南京210016

出　　处：《吉林大学学报（地球科学版）》2014年第2期527-539,共13页Journal of Jilin University：Earth Science Edition

基　　金：国家自然科学基金项目(41272098)

摘　　要：福建梅仙铅锌(银)矿床位于闽中裂谷带,是一大型多金属VMS型块状硫化物矿床。在详细野外地质考察基础上,通过对梅仙铅锌(银)矿区花岗斑岩2个样品的LA-ICP-MS锆石U-Pb年代学研究,确定其为燕山期花岗斑岩((148.9±1.4)Ma,(152.0±2.1)Ma)。全岩地球化学分析结果表明:所研究花岗斑岩具有高硅、富钾、中等含量的铝和全碱以及弱过铝质等特征。其稀土元素配分曲线普遍向右缓倾,且重稀土元素分配曲线比较平坦,富集大离子亲石元素和高强场元素,不具明显的Nb、Ta亏损,是产于碰撞后构造背景之下的高钾钙碱性I型花岗岩,其母岩浆形成后发生了角闪石、黑云母和斜长石等矿物高程度的的结晶分异作用。梅仙矿区花岗斑岩在空间上与铅锌硫化物矿体和赋矿层位关系密切,岩浆富含挥发分和大离子亲石元素,分异程度高,表明该燕山中期岩浆活动有利于矿区矽卡岩化成矿作用,并可对早期层控块状硫化物矿体进行强烈的叠加改造。Located in the Central Fujian Rift,the Meixian Pb-Zn deposit is a large volcanogenic massive sulfide Pb-Zn（-Ag）deposit.Based on a detailed field study,the authors identify Yanshanianporphyry granite（148.9±1.4Ma,152.0±2.1Ma）in the Meixian deposit by LA-ICP-MS zircon U-Pb dating.Geochemical analyses show the porphyry granites have high SiO2and potassium abundances, moderate Al2O3,alkaline contents,and weak peraluminous.Chondrite-normalized REE distribution pattern display right skewed shapes showing fractionation between LREE and HREE with flat HREE pattern.These granites are enriched in large ion lithophile elements（LILEs）and high field strength elements（HFSEs）without obvious depletion in Nb-Ta,indicating that they were high-potassium calcalkaline I-type granite formed in post-collision environment.Their parental magma were experienced strongly fractional crystallization of amphibole,biotite,plagioclase and some other accessory minerals. These porphyry granites are spatially associated with lead-zinc bodies,their magma are enriched in volatile component,large ion lithophile elements and have underwent high degree differentiation by fractional crystallization,indicating the Later Jurassic magmatism in the study area is very favorable for the skarn mineralization and extensively superimposed and reformed the earlier stage massive sulfur leadzinc ore bodies.

关 键 词：锆石U-PB年代学 地球化学 燕山期花岗斑岩 梅仙铅锌矿 成矿效应 

分 类 号：P618.51[天文地球—矿床学]