断裂控制热液蚀变及其成矿过程动力学计算模拟-以胶东焦家式金矿为例

Computational simulation of metallogenic dynamics can effectively promote understanding of the ore-forming process and kinetic mechanism. However, it is a difficult problem in the ore-forming process simulation to simultaneously couple various factors and processes such as structure deformation, heat transfer, fluid flow and chemical reaction in the metallogenic dynamic model. Therefore, we take gold deposits controlled by Jiaojia fault in the northwest of Jiaodong areas as the research objects in this project and develop a modeling system for three-dimensional dynamic modeling and automatic segmentation. Furthermore, we focus on the fracture–controlled hydrothermal mineralized alteration leading to fluid migration and rock physical and chemical properties changes, clarify the key factors affecting fluid seepage and the migration patterns of ore-forming materials in different ore deposits and reveal the spatiotemporal evolution regularities of ore fluid migration and confluence precipitation. Then, we build the three-dimensional dynamic models of mineralization process coupled with fracture deformation, heat transfer, fluid seepage and chemical reaction and develop computational simulation algorithms by the computational simulation softwares such as TOUGHREACT, FLAC and ANSYS. Moreover, a series of computational modeling experiments were carried out for mineralization processes under different conditions. we establish a kinetic mechanism for the fracture-controlled hydrothermal alteration and mineralization processes to provide the guidance for the deep concealed orebody prediction in ore deposits.

成矿动力学计算模拟能有效地促进对矿床成矿过程和动力学机制的了解，但如何在成矿动力学模型中同时耦合构造变形、热传递、流体流动和化学反应等多种因素和变化过程，是目前成矿过程计算模拟研究中的难点问题。本项目以胶东西北部地区焦家断裂控制的多个金矿床为研究对象，发展一套针对断裂等复杂地质体演化过程进行三维动力学建模和自动剖分的建模系统；顾及断裂引发流体运移和围岩物理化学性质变化，控制热液蚀变以及矿液沉淀过程，厘定影响实例矿床流体渗流的关键因素和成矿物质迁移形式，揭示矿液运移和汇流沉淀的时空演变规律；结合TOUGHREACT和FLAC、ANSYS等计算模拟软件，构建断裂变形-热传递-流体渗流-化学反应耦合的成矿过程三维动力学模型，开发计算模拟的算法和进行不同条件下的成矿动力学模拟实验，建立断裂控制热液蚀变和成矿过程的动力学机制，为矿床深边部隐伏矿体预测提供指导。

成矿动力学计算模拟能有效地促进对矿床成矿过程和成矿动力学机制的了解。本项目以胶东西北部地区焦家断裂控制的多个金矿床为研究对象，通过野外调查、资料整理和采样测试分析，明确了断裂-蚀变-矿化的空间位置关系，发展了一套针对断裂等复杂地质体进行三维动力学建模和定量研究的方法。通过研究多期次断裂构造演化的模式和性质以及热液蚀变化学反应过程，厘定了影响含矿热液运移的关键因素与成矿物质迁移形式，探索了成矿过程中构造应力场、热力场、流体渗流场以及化学反应之间的耦合关系，结合TOUGHREACT和FLAC 2D/3D、ANSYS等计算模拟软件，构建了含矿热液运移的多场耦合动力学模型，定量研究了成矿前后断裂构造应力场分布、断裂产状对焦家矿区成矿的控制作用，通过含矿热液与围岩的化学反应数值模拟，模拟获得了不同温压条件下成矿流体组分化学平衡浓度，进一步耦合温度、孔隙压力、流体流速等计算模拟数据，开发了成矿率计算模拟算法，探索了实例矿床成矿过程热液蚀变矿物溶解与沉淀的动力学机制。模拟结果表明断裂带对成矿的温度、流体压力演化有明显的控制作用，从体积应变、温度、流体的运移方向佐证了焦家断裂是焦家矿区重要的导矿和容矿构造，断裂带平缓且位于下盘的区域有利于形成蚀变岩型矿体，模拟结果印证了主断裂面以下的蚀变带具有良好的成矿环境，沿着断裂面伸展的深部区域可能会存在尚未发现的矿体。研究结果有助于加深对实例矿床成矿规律的了解，为新一轮的深边部找矿工作提供参考。