焦家金矿田断裂带结构及其成矿效应

The fluid flow and mineralization within hydrothermal systems are controlled by fault zone framework and its permeability structures. Ore-forming fluid dynamics of fault zone is one of the international frontiers in terms of economic geology. Jiaojia type gold deposit is the ideal choice for research of fault zone related mineralization. This project intends to focus on the fault structure and its mineralization effect. This project focuses on addressing two, closely related key scientific issues, i.e. the 4D structure and composition of fault zone, and mechanisms and kinetics of fluid flow and mineralization of Jiaojia Gold Field. The specific methods of the project include detailed 4D mapping of structure - alteration - mineralization in three world-class gold deposits (Jiaojia, Xincheng and Sizhuang), in situ and assemble analysis of gold-bearing minerals and fluid inclusions and other multidisciplinary methods and techniques. This project will elucidate the framework and tectonic evolution of the ore-controlling Fault zone, characterize the internal structure of the ore-controlling Fault zone and the 4D temporal and spatial variation of its mineral and chemical composition, compare permeability structure differences of rocks from fault zone and undeformed wall rock, identify sophisticated framework of fault zone which controlled the gold mineralization and aggregated distribution, and the temporal and spatial evolution characteristics of permeability structure, reveal the process of ore-forming fluid dynamics and its genetic mechanism. This will deepen our understanding of hydrothermal metallogenic system and regional metallogenic regularity, and provide theoretical support for scientific prediction of deep prospecting.

热液系统的流体流动与成矿作用受控于断裂带格架及其渗透性结构，断裂带流体成矿动力学是矿床学重大国际前沿，“焦家式”金矿是研究断裂带流体成矿作用的理想选择。项目拟聚焦断裂带结构及其成矿效应，针对焦家金矿田断裂带四维结构与组成、流体流动与成矿机制两个关键科学问题，通过对焦家、新城和寺庄三个世界级金矿床详细的构造-蚀变-矿化四维填图、载金矿物和流体包裹体原位-组合分析等多学科交叉融合的方法技术，解析控矿断裂带格架与构造演化，厘定控矿断裂带内部结构及其矿物与化学组成的四维时空变化，对比断裂带内岩石与未变形围岩的渗透性结构差异，查明控制金成矿作用与金矿化聚集分布的断裂带精细格架与渗透性结构的时-空演变特征，揭示流体成矿动力学过程与成因机制。为深化对热液成矿系统与区域成矿规律的认识、从而提高深部找矿的科学预测能力提供理论支撑。

热液系统的流体流动与成矿作用受控于断裂带格架及其渗透性结构，断裂带流体成矿动力学是矿床学重大国际前沿，“焦家式”金矿是研究断裂带流体成矿作用的理想选择。项目组运用多学科方法，针对断裂带四维结构与组成、流体流动与成矿机制两个关键科学问题进行深入研究，取得系列成果。通过热液独居石原位U-Pb定年和综合研究，查明胶东金成矿事件主要集中在120Ma古太平洋板片俯冲回撤形成的张性背景下，含金H2O-CO2流体沿深大断裂运移并沉淀在NE-NNE向拆离断裂带中。通过控矿构造解析，发现成矿期的断裂构造活动诱发破裂应力在特定部位集中，引起了渗透性空间分布差异性，导致金矿床群聚分布在控矿断层产状变化及其与基底构造带交汇部位；揭示焦家断裂带成矿早阶段的左行正断活动控制了矿体整体SW侧伏，成矿晚阶段的右行逆断活动控制了富矿柱NE侧伏，由NNE转向NE的构造节点控制了富矿柱的空间定位。通过成矿流体系统研究揭示，伴随着压力的降低，成矿流体发生了不混溶作用，金络合物失稳导致金沉淀，水-岩反应过程中的硫化作用和由压力波动导致的流体不混溶是金沉淀的两种主要机制。发表论文17篇，培养了一批青年地质科技人才。