超临界流体在花岗岩成岩成矿过程中的作用——以香花岭花岗岩型铌钽矿床(430)为例

ROLE OF THE SUPERCRITICAL FLUID IN THE PROCESS OF GRANITIC ROCKFORMING AND MINERALIZATION:TAKING THE GRANITIC NbTa DEPOSIT IN XIANGHUALING AREA AS AN EXAMPLE

以香花岭花岗岩型铌钽矿床为例，把花岗岩熔体内的组分按其活动性分为活动组分、有效活动组分和惰性组分３类；论述了花岗岩熔体在超临界流体作用下（流体—熔体，流体—岩石作用），粘度、内压、结构、组分活动性及相对含量等，随岩浆演化而呈现的一系列变化，同时，铌钽等成矿元素随岩浆体系内超临界流体聚集而富集，随体系内射气分异作用的发生而矿化，成岩作用和成矿作用表现为一连续过程，在这一过程中，结晶分异作用和交代、溶蚀作用并存，沉淀作用和溶解作用交替，实质上是岩浆体系的内部分异作用或自组织作用过程，成矿作用发生在广义岩浆作用范畴，矿床属岩浆成因。

In this paper,granitic NbTa deposit in Xianghualing is taken as an example.According to the mobility of components in granite melt,the authors classify them into three families:active component,efficacious active component and indolent component,and discuss that a series of physical and chemical properties including viscosity,inner pressure,structure,mobility and contents of components in magmatic system change systematically under the action of the supercritical fluid(the interaction of fluidmelt and fluidrock),with the evolution of magma from early to late stages.In the mean while,Nb,Ta and other oreforming elements become richer and richer and cause the mineralization as the supercritical fluid concentrates progressively during the magma′s evolution and as the emanationdifferentiation occur within the magma system.Mineralization and rockforming are a successive process in which fractional crystallization of magma,metasomatism and resorption coexist,and precipitation and dissolution take place alternatively.The formation of granitic NbTa deposit in Xianghualing area is in fact a process of differentiation or selforganization in magmatic system under the action of supercritical fluid.Mineralization comes out in the generalized magmatism and granitic NbTa deposit belongs to magmatic genesis.