铜陵狮子山矿田矽卡岩铜(金)成矿系统三维动力学计算模拟及其意义  

3D Computational Geodynamic Modeling of Skarn Copper(Gold)Mineralization System and its Implication for Ore Formation in the Shizishan Orefield,Tongling District,Eastern China

作　　者：周飞虎 刘亮明[1] 刘洪升 盛欢 伍红志 闵令帅 毕晨曦 ZHOU Feihu;LIU Liangming;LIU Hongsheng;SHENG Huan;WU Hongzhi;MIN Lingshuai;BI Chenxi(MOE Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring,Computational Geosciences Research Centre,Central South University,Changsha 410083,Hunan,China;Dongguashan Copper Mine,Tongling Nonferrous Metals Group Holding Co.,Ltd.,Tongling 244000,Anhui,China)

机构地区：[1]中南大学计算地球科学研究中心,教育部有色金属成矿预测与地质环境监测重点实验室,湖南长沙410083 [2]铜陵有色金属集团股份有限公司冬瓜山铜矿,安徽铜陵244000

出　　处：《大地构造与成矿学》2023年第6期1242-1255,共14页Geotectonica et Metallogenia

基　　金：国家自然科学基金项目(41772351)资助。

摘　　要：狮子山矿田产有铜陵地区乃至整个长江中下游成矿带最大的矽卡岩型铜(金)矿床,由于成矿特征的复杂性,矿田内巨大的层状矽卡岩矿床的定位机制一直存在争议。为了探讨本区成矿的动力学机制及其控制因素,本次研究基于矿田内全部的勘探资料建立了矿田三维地质模型,在此基础上建立动力学模型,在FLAC3D平台进行岩体冷却过程力‒热‒流耦合动力学计算模拟。模拟结果显示在拉张构造应力环境中,在浅部东、西狮子山矿床产出部位只在岩体接触带上形成了规模不大的高扩容区(体积应变值≥1.2%),而在深部层状矿体产出的地层中形成了大规模的层状高扩容变形区,同时流体也向高扩容区汇聚。这些流体汇聚的高扩容区与已知矿体的容矿空间高度吻合,由此推断矿体的定位受控于岩体冷却过程中产生的扩容和流体流动。石炭系中流体汇聚的高扩容空间的规模远大于已知的成矿规模,表明矿田深部的冬瓜山矿床仍存在较大的增储潜力。改变模型的边界条件和模型组成单元的特征参数进行假设模型计算实验,结果表明拉伸的构造应力环境为大规模汇流容矿空间的形成提供了有利条件,并且赋矿地层中更弱的抗剪切强度和上覆地层低渗透的孔隙特征也是控制矿体定位空间和成矿规模的重要因素。The Shizishan orefield hosts the largest Cu(Au)skarn deposit,the Dongguashan deposit,in the Tongling district,even in the whole Lower Yangtze Metallogenic Belt.The major orebody of the Dongguashan deposit is strataboud and stratiform Cu(Au)skarn which has more than 1 Mt Cu reserves,accounting about 60%of the total reserves of the orefield.The localization mechanism of this significantly large stratiform orebody is still actively debated because of the complexity of the metallogenic characteristics.For better understanding the dynamic mechanism and the controlling factors for ore formation,we constructed a 3D geological model of the orefield by integrating all available exploration data,and then carried 3D computational geodynamic modelling in the FLAC3D platform,to simulate the coupled mechano-thermo-hydrological(MTH)processes during the cooling of the intrusion and mineralization in the Shizishan orefield.The results of the computational geodynamic modelling show that,in the extensional tectonic regime,the shallow high-dilation zones(volumetric strain≥1.2%)are not significantly large and located in the contact zone that hosts orebodies of the East and West Shizishan deposit;while the deep high-dilation zones,where the fluids from the intrusion and sedimentary rocks are focusing,are the largest and most intensive zones located in the carbonate rocks of the mid to upper Carboniferous that hosts the Dongguashan ore deposit.Because these fluid focusing high-dilation zones are spatially consistent with the known orebodies,we conclude that the fluid focusing high-dilation zones were produced during the intrusion cooling processes and controlled the ore localization in the Shizishan orefield.Furthermore,the scale of the fluid focusing high-dilation zones in the mid to upper Carboniferous formation is larger than that of the known Dongguashan deposit,indicating that the mid to upper Carboniferous formation are favorable for the Cu(Au)mineralization.For investigating ore formation-controlling factors,we conducted dynam

关 键 词：成矿动力学 计算模拟 矽卡岩矿床 狮子山矿田 铜陵 

分 类 号：P628[天文地球—地质矿产勘探] P612[天文地球—地质学]