地质流体自然类型与成矿流体类型

水是地球上特征的地质流体 ,大部分矿床是在水热流体参与下形成的 ,但并不是所有流体都参与成矿。根据水的主要存在环境把水分为地质流体和成矿流体类型。各种环境广泛存在的水所构成的地质流体 ,又可细分为大气降水、盆地建造水、海水、岩浆水和变质水各种类型。研究认为成矿流体的形成主要与地质作用有关 ,是地质流体在特定环境特定演化阶段形成的特征产物。成矿流体则可划分为高温硅钾卤水、中温碳酸盐卤水及低温硫酸盐卤水。高温硅钾卤水中硅钾组分含量与温度、盐度成正相关关系 ,并且其中富含F-、B2 O3组分。这些特征与成矿作用中的高温钾化、硅化、萤石化及电气石化蚀变及热水沉积特征是一致的 ,高温成矿流体在演化过程中依次可以演变为中温或低温成矿流体。中温成矿流体以碳酸盐型流体为主 ,以富含Mn2 +,Fe2 +,Mg2 +的碳酸盐化合物为特征。低温成矿流体一般为硫酸盐型卤水 ,主要是Ba2 +,Sr2 +,Ca2 +的硫酸盐化合物 ,在海陆相各环境中广泛存在。大洋底部成矿流体是特殊环境下的地质流体类型 ,具有更广泛的温度区间 ,可以是从高温到中低温的系列流体类型 ,并且具有特殊地球化学组成。一般形成高温硅钾卤水与岩浆作用或变质作用有关 ,由于充分的水岩交代作用 ,可以获得较高的温度及足够的溶质组分 ;

TYPES OF GEOLOGICAL FLUIDS AND ORE-FORMING FLUID

Water is the characteristic geological fluid in the Earth. Most of the deposits form through the participation of hydrothermal fluid. However, not all of the fluids play a role in the minerogenesis. Water is classified into two types-geological fluid and mineralizing fluid-in this paper, based on the main environment where water exists. Geological fluid is one kind of water that widely exists in various enviornments. It is divided into atmospheric water, basin formation water, seawater, magmatic water, and metamorphic water, according to the environment where water exists. The study suggests that the formation of ore|forming fluid is mainly related to the geological process and it is the characteristic product formed in certain environments and evolution stages. This paper classifies the ore|forming fluid into high temperature Si|K brine, moderate temperature carbonate brine and low temperature sulfate brine. The content of Si|K in high temperature Si|K brine is directly correlated to the temperature and salinity, and the contents of F and B 2 O 3 are rich. These features are identical with the features of high temperature K|alteration, silication, fluoritization, tourmalinization and hydrothermal sedimentary feature in metallogeny. In the course of evolution, high temperature ore|forming fluid can be changed into moderate temperature fluid and low temperature fluid gradually. Moderate temperature fluid mainly contains carbonate|type, which is featured by high content of carbonate compounds of Mn 2+ , Fe 2+ , Mg 2+ . Low temperature ore|forming fluid is generally sulfate brine and mainly contains sulfate with Ba 2+ , Sr 2+ , Ca 2+ , and this type of fluid widely occurs in all kinds of environment in sea facies and continental facies. The ore|forming fluid on the bottom of ocean is a type of geological fluid on the special condition in the wide range of high to moderate temperature. And this type of fluid series contains special geochemical composition. Formation of high temperature Si|K|brine is generally related to magmatism or metamorphism and the quite high temperature and abundant solution composition in the brine are due to the complete replacement between water and rocks. However, the formation ranges of moderate and low temperature ore|forming fluids are more extensive than that of high temperature ones. In general, geothermic heat and tectonic heat can generally provide the thermal energy for moderate and low temperature ore|forming fluid.