宁芜盆地白象山铁矿床成矿作用过程数值模拟

Numerical simulation of the process of deposit formation in Baixiangshan iron deposit,Ningwu Basin

白象山铁矿床是宁芜火山岩盆地钟姑矿田中典型的玢岩型铁矿床,主矿体赋存于闪长岩和黄马青组砂页岩接触带部位的内带-正带,呈似层状产出。本文采用数值模拟的方法研究探讨白象山铁矿床成矿过程的动力学机制以及汇流容矿空间的形成。在建立白象山矿床典型剖面以及三维实体模型的基础上,选取典型剖面,基于FLAC 3D系统,对白象山铁矿床的充填过程进行数值模拟。模拟结果显示,白象山铁矿床存在容矿汇流空间,其形成受力-热-流体的耦合作用制约;扩容空间的形成可为矿质的沉淀以及交代作用提供有利的成矿空间,并为流体的汇聚提供有利场所,也表明白象山铁矿床的成矿过程与力学作用密切相关。本文的模拟研究充分揭示了白象山铁矿床成矿过程中的物理过程,岩石不同的力学性质以及接触带的形态是控矿的重要因素,这为进一步的找矿工作提供了依据。

The Baixiangshan iron deposit is a typical porphyrite iron deposit, which lies in Zhonggu ore field in Ningwu volcanic basin. The main orebodies with an output in the shape of layers are within the positive contact zone of diorite and Huangmaqing sandshale. The paper studies the geodynamic mechanism and the formation of the fluid-focusing dilation space with the approach of numerical simulation of mineralization process of the Baixiangshan iron deposit with the help of FLAC 3D. The results indicate that the flow-focusing dilation space does exist in Baixiangshan iron deposit, and its formation is under the effect of the coupled mechano- thermo-hydrological process. The flow-focusing dilation space allows mineral precipitation and metasomatosis as well as a place for fluid confluence. It shows that the ore-forming process in Baixiangshan is closely related to the mechanical effect. The research reveals the physical process of the ore-formation in Baixiangshan iron deposit. Different mechanical properties and contact zone of rocks are important factors of the controlling of ore-formation, which are also suggestive of further deposit exploration.