安徽铜陵新桥铜-硫-铁矿床矶头岩体的矿物学和锆石U-Pb年代学及其地质意义  

Petrography and U-Pb Zircon Geochronology of the Jitou Pluton in the Xinqiao Cu-S-Fe Deposit,Tongling Area,Anhui Province,and Its Geological Significance

作　　者：宋扬[1] 杜杨松[1] 张智宇[2] 马宏[1] 朱晓强[1] 

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083 [2]中国地质科学院地质研究所,北京100037

出　　处：《地质科技情报》2017年第1期33-40,共8页Geological Science and Technology Information

基　　金：中国地质调查局地质调查项目(E90165;12120113069900;12120115034401)

摘　　要：长江中下游成矿带铜陵矿集区内的许多矿床皆与中生代岩浆岩的侵入密切相关,选取新桥矿床矶头岩体为研究对象,进行LA-ICP-MS锆石U-Pb定年以及岩体地质和矿物学研究。锆石的高Th/U比值特征及典型岩浆锆石环带显示其为岩浆成因。矶头岩体中主体石英闪长岩16个测点的加权平均年龄为(141.6±1.1)Ma,后期侵入的闪长玢岩20个测点加权平均年龄为(129.95±0.6)Ma。两者均形成于早白垩世,矿区内岩浆活动至少有两期,主岩浆作用为141 Ma。矶头岩体是由幔源岩浆上侵至13~15km中地壳先形成深部岩浆房,发生结晶分异和同化混染,随后在构造扰动与岩浆脉动下,深部岩浆房中的岩浆沿构造薄弱面上侵至7~8km,冷凝固结形成,其结晶温度大约为800℃。矶头岩体约束成矿时代及成矿作用,新桥矿床经由高温热液交代作用,并经后期热液多次叠加改造成矿。Tongling ore district is closely related to the Mesozoic intrusive igneous rocks which is equivalent to some deposits in the Yangtze River metallogenic belt.The paper,taking the Jitou pluton as the study object,studies LA-ICP-MS zircon U-Pb dating to supplement Xinqiao pluton＇s geology and mineralogy content.The high Th/U ratios and typical magmatic oscillatory zoning of zircons indicate their magmatic origin.The weighted average age of the quartz diorite from 16 testing spots in the major part of Xinqiao pluton is（141.6±1.1）Ma,while the weighted average age of the late intrusive diorite dikes from 20 spots is（129.95±0.6）Ma,both of which were formed in the Early Cretaceous.There are at least two times of magmatic activity,with the main magmatism time at 141 Ma.The magma is derived from the deep mantle emplacing along the tectonic crack to the middle crust（about 13-15km）and formed the deep magma chamber accompanied by fractionation crystallization and assimilation.Then,under the influence of geological structure,the magma in the deep magma chamber emplaced again along the weak tectonic crack to the upper crust（7km to 8km）and eventually formed the Jitou pluton,with the crystallization temperature about 800 ℃.Xinqiao deposit was formed through the high-temperature hydrothermal metasomatic,and superimposed hydrothermal process many times later.

关 键 词：矶头岩体 矿物学 锆石定年 新桥铜硫铁矿床 安徽铜陵 

分 类 号：P588.12[天文地球—岩石学]