皖南宁国竹溪岭钨银矿床及相关岩体的同位素地质年龄  

Isotopic Ages of the Zhuxiling W-Ag Ore Deposit and Related Plutons in Ningguo, Southern Anhui

作　　者：黄马 徐晓春[1] 谢巧勤[1] 韦导忠[2] 徐生发[3] 王德恩[3] HUANG Ma;XU Xiaochun;XIE Qiaoqin;WEI Daozhong;XU Shengfa;WANG Deen(School of Resources and Environmental Engineering,Hefei University of Technology,Hefei 230009,Anhui,China;Management Center of Public Geological Investigation of Anhui Province,Hefei 230001,Anhui,China;Geological 332 Team of Bureau of Geology and Mineral Resources of Anhui Province,Huangshan 245000,Anhui,China)

机构地区：[1]合肥工业大学资源与环境工程学院,安徽合肥230009 [2]安徽省公益性地质调查管理中心,安徽合肥230001 [3]安徽省地质矿产勘查局332队,安徽黄山245000

出　　处：《大地构造与成矿学》2018年第2期279-290,共12页Geotectonica et Metallogenia

基　　金：国家自然科学基金(41472066);安徽省国土资源厅公益性项目(2012-g-9)联合资助

摘　　要：皖南宁国竹溪岭钨银矿床是近年来发现的一个与花岗岩类有关的矽卡岩型矿床,准确厘定其成矿年龄及相关侵入岩体的年龄有利于深入认识区域岩浆作用与成矿作用的规律。本文在矿床地质调查的基础上,应用现代同位素定年技术开展地质年代学研究,获得矿床矿石中的辉钼矿Re-Os模式年龄为142.7±2.1 Ma和142.9±2.1 Ma,相关侵入岩体花岗闪长岩、花岗斑岩和花岗闪长斑岩的LA-ICP-MS锆石U-Pb年龄分别为139.8±1.8 Ma、143.3±1.9 Ma、140.2±1.7 Ma,显示矿床的成矿年龄与侵入岩体的成岩年龄基本一致,为燕山晚期早白垩世。矿床矿石中的辉钼矿的Re含量指示成矿物质来源于地壳和地幔的混合;与成矿相关侵入岩的稀土元素和Hf同位素组成特征指示成岩物质也具有壳幔混源特征,显示成矿物质来源与成岩物质来源具有一致性。区域岩浆岩和矿床的对比表明,与之相邻的长江中下游地区、浙西地区和赣东北地区乃至整个华南地区这一时期发生了大规模的岩浆作用和钨锡多金属成矿作用,显示扬子板块在此阶段处于岩浆–成矿大爆发时期,皖南地区的成矿时代对应于华南中生代三次大规模岩浆作用和成矿作用的第二阶段。The Zhuxiling W-Ag ore deposit is a newly discovered skarn-type deposit situated in Ningguo city of the southern Anhui province.To constrain the ages of the ore mineralization and related plutons,an integrated geochronological investigation has been carried out on the basis of ore geology survey.Analyses of two molybdenite separates yielded Re-Os model ages of 142.7±2.1 Ma and 142.9±2.1 Ma,respectively;whereas zircons from the granodiorite,granodiorite porphyry,and granite porphyry were dated to be of 139.8±1.8 Ma,140.2±1.7 Ma,and 143.3±1.9 Ma,respectively,by LA-ICP-MS U-Pb method.The ages of the ores and related granitic rocks are identical within analytical error,suggesting they all formed in the Early Cretaceous.The high rhenium contents(39.7×10?6 to 41.9×10?6)of molybdenite may imply a mixed source of crust and mantle,which is also supported by REE characteristics and Hf isotopic compositions of the related granitic rocks.A comprehensive compile of the ore deposits and magmatic rocks in this and adjacent regions suggests that the whole South China experienced large-scale magmatism and polymetallic W-Sn mineralization in the late Yanshanian,which constitutes a booming period of magmatism and ore mineralization in the Yangtze Plate.This metallogenetic epoch of the southern Anhui province is corresponding to the second stage of the Mesozoic large-scale magmatism and mineralization in South China.

关 键 词：辉钼矿RE-OS年龄 LA-ICP-MS锆石U-PB年龄 矽卡岩型钨银矿床 皖南宁国竹溪岭 

分 类 号：P612[天文地球—矿床学] P597[天文地球—地质学]