盆地流体动力学演化及其成矿效应——以广东富湾-长坑银金矿床为例  

Dynamic Evolution of Basin Fluid and Its Metallogenic Effects: A Case Study of Fuwan-Changkeng Silver-gold Deposit, Guangdong Province

作　　者：吕万军[1] 李思田[2] 刘少明[3] 段振豪[2] 张文淮[2] 焦养泉[2] 庄新国[2] 

机构地区：[1]中国科学院广州地球化学研究所,广东广州510640 [2]中国地质大学资源学院,湖北武汉430074 [3]揭阳职业技术学院,广东揭阳522000

出　　处：《矿床地质》2002年第3期223-231,共9页Mineral Deposits

基　　金：国土资源部重点科技攻关项目 (95 0 110 3 );国家杰出青年基金 (4 982 5 5 3 1)项目的资助

摘　　要：文章以广东富湾_长坑层控银金矿床为实例 ,基于各阶段盆地中温度场、压力场和流动场的动力学演化过程与成矿效应的研究 ,发现盆地流体转变为成矿流体具有漫长的演化与更迭历程 ;构造演化和盆地的沉积充填特征 ,不仅直接影响着流体在盆地中的流动样式 ,而且直接影响着成矿物质空间存在形式的变化以及“流体_岩石”体系中各要素间的再分配。流体的大规模活动及大型矿床的形成与大幅度的构造运动、沉积作用、岩浆活动、火山活动等宏观地球动力作用有关 。The Fuwan_Changkeng silver_gold deposit, a stratabound super_large deposit discovered in South China in 1990's, occurs in the detachment zone along the unconformable surface between the underlying Carboniferous limestone and the upper Triassic shale and sandstone. Previous study conducted by the authors shows that the ore_forming fluid originated from basin formation fluid. In this paper, the evolution of the temperature_pressure field and the fluid regime were simulated spatiotemporally on the basin scale, and the process of the mobilization, transportation and deposition of the ore_forming matters by the basin fluid was discussed. The results of basin modeling indicate that the formation, the movement and the thermodynamic evolution of the ore_forming fluids are controlled by the tectonic evolution and the sedimentary filling characteristics of the basin. The fluid migrated from formation water to hydrocarbons_bearing fluid and to ore_forming fluid in the deep layers of the basin under high temperature and pressure, and migrated from ore_forming fluid to residual fluid with low content of metals in shallow surroundings. Gold and silver were accumulated and concentrated by basin fluid from the depth at high temperature and pressure, moved upward under the driving force of the high_speed compaction, and migrated to shallow places and precipitated at a suitable location with relatively low temperature and pressure. The fluid regime changed with the evolution of the basin. Large amounts of hot fluid moved from deep basin to the shallow rapidly at the stage when the basin subsided with high burial rate, while large volume of cold surface water flowed from platform to basin at the uplift. Thus the mixture of hot ore_bearing fluid with deep and surface cold water could have occurred in the main pathways such as faults and detachment zones during the shifting from subsidence to uplifting or vice versa , which might lead to the mineralization and the formation of the deposit. The large deposits respond to the joint for

关 键 词：流体动力学 成矿效应 银金矿床 盆地 成矿作用 成矿流体 构造运动 岩浆活动 

分 类 号：P618.52[天文地球—矿床学] P618.51[天文地球—地质学]