摘要
流体温度-密度-盐度关系化学模式显示,水下亚系统是一种火山作用形成的富含NaCl向海底释放的流体系统,该系统形成块状硫化物矿床;水上亚系统是陆相火山岩地区的地下低盐度低温流体系统,形成了浅层低温热液型和热泉型矿床。由流体的质量方程、能量方程和运动方程的特点可以看出,在成矿作用过程中的流体运动,受到构造-流体-成矿系统的关系中多种因素的影响,如介质的孔隙度、流体密度、渗透率、流体的黏度和流体内压力等。以世界一些陆相火山地区的金矿为例进行讨论,充分证明了陆相火山地区的金矿流体的运动方式具有两种类型:一类是成矿流体沿岩石的孔隙流动,如伊尔曼得金矿等;另一类是成矿流体沿裂隙流动,如阿希金矿等。虽然这些金矿形成于同一火山岩地区,但是,流体在围岩的孔隙和断裂中以不同的方式运动,流体的内压力、流体的密度将发生不同的变化,同时引起流体的氧逸度、pH值、盐度产生不同的改变。由此表明流体运动的方式和扩散影响了成矿环境。
The chemical model of fluid temperature density salinity system indicate that subaquatic subsystem is a fluid system, which is rich in NaCl, is formed by volcanism and spreads toward the bottom of sea, and in which massive sulfide deposits are formed. Abovewater subsystem is a fluid system with subsurface low salinity and low temperature in continental volcanic terrain, in which epithermal and hot spring deposits would be formed. Feature of fluid mass equation, energy equation and motion equation can show that fluid movement in ore forming process would be affected by a lot of factors, such as porosity of medium, fluid density, permeability, fluid viscosity and fluid internal pressure. Several examples of gold deposits in continental volcanic terrains in the world show that their tectonics fluid mineralization system might effect ore forming environment. Fluid from gold deposits of continental volcanic terrain in the world has two types of movement: one is that ore forming fluid pass through pores of rocks, with the Yelmend gold deposit as an example. The other is that ore forming fluid pass through fractures, with the Axi gold deposit as an example. Although these gold deposits were formed in the same volcanic terrain, but fluid flowed through pore or fracture in different way, respectively, therefore, fluid internal pressure and fluid density would be changed in different level, and fluid oxygen fugacity, pH and salinity would also be changed in different level. Therefore, the movement and diffusion of fluid can affect ore forming environment.
出处
《地球化学》
CAS
CSCD
北大核心
2004年第2期197-207,共11页
Geochimica
基金
国家"305"基金项目(96-915-03-06-02)
