地质流体的输运-化学反应与成矿作用微观机制研究——以安徽冬瓜山层控夕卡岩型铜矿床为例

TRANSPORT-CHEMICAL REACTION OF GEO CHEMICAL FLUID AND MICROMECHANISM ORE-FORMING PRO CESSES:A CASE STUDY FOR THE DONGGUASHAN STRATABOUND SKARN Cu DEPOSITS,ANHUI PROVINCE,CHINA

以冬瓜山层控夕卡岩型铜矿床的基本地质特征为基础建立了成矿作用的地质模型,运用成矿作用动力学理论将其转化成动力学模型,然后对动力学模型求解得到刻划矿质在断裂—多孔介质体系中输运-化学反应演化规律的解析解。研究揭示冬瓜山矿床的成矿微观机制为:成矿流体受外力的驱动在断裂-多孔隙复杂介质的输运过程中,由平流、动力弥散、扩散作用与交代反应、溶解-沉淀反应相互耦合作用而成矿。介质的有效孔隙度和渗透率等动力学参数是矿体的空间分布及规模大小的主要控制因素。模拟结果合理地解释了矿体的空间展布、矿石品位及矿石结构构造的空间变化特征等矿床的基本地质特征。本研究显示,一旦成矿过程的基本动力学参数能确定,可预测成矿的位置、矿体长度、厚度及贫富变化的规律,显示动力学研究具有潜在的重要应用价值。本文为研究复杂介质中矿床形成的微观机制提供了一种新的思路。

A dynamic model of ore-forming proce sses of the Donguashan strata-bound skarn copper deposit is derived from geological model on the basis of comprehensive actually geological work.Then the analytical solutions describing the evolution of ore-forming system are worked out .The ore-forming mechanism is re-vealed by the present study as follow s:Orebodies were formed by complex d ynamic processes of coupling transportation with chemical reactions of ore-forming materials(including advection,molecular diffusion and dispersion,metasomatism,and diss olution-deposition etc.).The ore-forming processes are cont rolled by a series of dynamic parameters of the m edia,such as efficient porosity,permeability.By dynamic modeling reasonable interpretation to important geological phenomena such as sp atial distribution of orebodies,th e spatial variation of copper grades a nd structures of ores can be obtained.It is demonstrated that once the values of the dynamics parameters are given,it would be possible to predi ct the locations,the length and width of the ore bodies as well as the v ariation regularities of copper gra des in ores formed by a specified case.Though a number of assumptions were made that resulted in,to some extent,an idealized system,the study here provides a framework for s tudying the mechanics of transport i n fractured porous media and as s uch can be regarded as the base for solutions to problems developed for thi s purpose.By applying the analytical solutions to field or lab oratory data,they will assist in parameter identification,thus enabli ng prediction to be made with models of more elaborate fractured systems.