江西相山火山岩型铀矿床构造‒流体动力学数值模拟研究  

Numerical Modeling of Coupled Hydraulic-mechanical Processes Related to Volcanic-type Uranium Mineralization in the Xiangshan Basin,Jiangxi Province

作　　者：黄沁怡 李增华 许德如[1,3,4] 郭福生 邓腾[3,4] 吴志春 周万蓬[3,4] 韦晓艳[4] 郭世超 张衡 HUANG Qinyi;LI Zenghua;XU Deru;GUO Fusheng;DENG Teng;WU Zhichun;ZHOU Wanpeng;WEI Xiaoyan;GUO Shichao;ZHANG Heng(CAS Key Laboratory of Mineral and Metallogeny,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;University of Chinese Academy of Sciences,Beijing 100049,China;State Key Laboratory for Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,Jiangxi,China;School of Earth Sciences,East China University of Technology,Nanchang 330013,Jiangxi,China)

机构地区：[1]中国科学院广州地球化学研究所矿物学与成矿学重点实验室,广东广州510640 [2]中国科学院大学,北京100049 [3]东华理工大学核资源与环境国家重点实验室,江西南昌330013 [4]东华理工大学地球科学学院,江西南昌330013

出　　处：《大地构造与成矿学》2024年第2期338-351,共14页Geotectonica et Metallogenia

基　　金：国家自然科学基金项目(42172329、41972080、41930428、42002090);江西省技术创新引导类计划项目(20212AEI91008);中国铀业有限公司-东华理工大学核资源与环境国家重点实验室联合创新基金项目(NRE2021-08)联合资助。

摘　　要：相山铀矿床是中国最大的火山岩型铀矿床,矿体的空间分布主要受断裂构造控制,但构造对流体运移的具体影响,以及对成矿的控制机制尚未明确。本文基于FLAC3D软件,运用数值模拟方法对相山地区的构造‒流体‒成矿系统进行研究。首先通过总结分析前人研究资料得到模拟所需的地质模型,然后设置模型中的物性参数、边界条件和初始条件,并在此基础上进行相山铀矿床成矿过程数值模拟中应力场和流体场的耦合模拟计算,最后得到了不同构造背景下的体积应变率、流体流速和流动模式等。模拟结果显示,坡度的存在为浅部流体下渗提供了一定的驱动力,在挤压构造环境下,流体趋向于通过断层向上流入红层,体积应变率最大的区域位于红层中;在拉张构造环境下,流体趋向于通过断层向下流入基底,体积应变率最大的区域位于火山岩层中的断层内。因此,构造拉张作用有利于浅部氧化性流体的下渗,并且构造拉张环境下的断层活化能够形成有利于成矿的空间。The Xiangshan uranium deposit is the largest volcanic rock-type uranium deposit in China.The spatial distribution of the ore bodies is mainly controlled by the faults,but the specific influences of the structure on fluid migration and mineralization have not been clearly defined.Using FLAC3D software,numerical modelling was conducted to study the mechanical-fluid flow-mineralization system in the Xiangshan Basin.The geological model required for the numerical simulation was obtained by summarizing and analyzing previous research data.Then the physical parameters,boundary conditions,and initial conditions were assigned in the models.The coupling relationships of the stress and fluidic fields of the Xiangshan uranium mineralization processes were also numerically simulated.On the basis of the obtained volumetric strain rates,fluid flow patterns,and fluid flow rates under different tectonic environments,the genesis and mechanism of the deposit under different tectonism were analyzed.The modeling results showed that the topographic difference was a limited driving force for fluid infiltration.Under the compressive tectonic environment,the fluids tended to flow upward through the fault into the red beds,where the largest volumetric strain rate was located.In the extensional tectonic environment,the fluids were inclined to flow downward through the faults into the basement,and the region with the largest volumetric strain rate was located within the faults in the volcanic rocks.This study shows that tectonic extension is conducive to the infiltration of shallow oxidizing fluids,and fault activation under an extensional tectonic environment can form a space conducive to mineralization.

关 键 词：数值模拟 构造作用 流体运移机制 

分 类 号：P613[天文地球—矿床学] P628[天文地球—地质学]