成矿流体动力学的原理、研究方法及应用

摘要

Fluid flow is an integral part of hydrothermal mineralization,and its analysis and characterization constitute an important part of a mineralization model.The hydrodynamic study of mineralization deals with analyzing the driving forces,fluid pressure regimes,fluid flow rate and direction,and their relationships with localization of mineralization.This paper reviews the principles and methods of hydrodynamic studies of mineralization,and discusses their significance and limitations for ore deposit studies and mineral exploration.The driving forces of fluid flow may be related to fluid overpressure,topographic relief,tectonic deformation,and fluid density change due to heating or salinity variation,depending on specific geologic environments and mineralization processes.The study methods may be classified into three types,megascopic（field） observations,microscopic analyses,and numerical modeling.Megascopic features indicative of significantly overpressured（especially lithostatic or supralithostatic） fluid systems include horizontal veins,sand injection dikes,and hydraulic breccias.Microscopic studies,especially microthermometry of fluid inclusions and combined stress analysis and microthermometry of fluid inclusion planes（FIPs） can provide important information about fluid temperature,pressure,and fluid-structural relationships,thus constraining fluid flow models.Numerical modeling can be carried out to solve partial differential equations governing fluid flow,heat transfer,rock deformation and chemical reactions,in order to simulate the distribution of fluid pressure,temperature,fluid flow rate and direction,and mineral precipitation or dissolution in 2D or 3D space and through time.The results of hydrodynamic studies of mineralization can enhance our understanding of the formation processes of hydrothermal deposits,and can be used directly or indirectly in mineral exploration.%流体流动是热液成矿作用不可或缺的一部分,其研究是建立成矿模式的重要组成部分。成矿流体动力学主要研究流体流动的驱动力、压力状态、流速、流动方向以及它们与矿床定位的关系。文中总结了成矿流体动力学的基本原理和方法,并对其在成矿作用研究和矿产勘查上的重要性和局限性进行了讨论。流体流动的驱动力可以是流体的超压、地势差、构造变形以及因温度或盐度变化而引起的流体密度变化。成矿流体动力学的研究方法包括宏观（野外）观察、微观分析和数值模拟3个方面。指示流体超压的宏观地质特征包括水平脉体、砂岩灌入体和水力致裂角砾岩等。微观研究,尤其是流体包裹体测温以及流体包裹体面的应力-温压分析,可以为成矿流体的温度、压力和流体-构造关系提供重要的信息,并起到制约流体模型的作用。数值模拟方法包括解流体流动、热传递、岩石变形及化学反应的偏微分方程和模拟流体的压力、温度、流速、流动方向在时间和二维或三维空间的分布。成矿流体动力学的研究结果可以提高我们对热液矿床成矿过程的认识,并可直接或间接地应用于找矿勘探。