地学前缘 ›› 2024, Vol. 31 ›› Issue (1): 239-266.DOI: 10.13745/j.esf.sf.2024.1.40

• 陆内成矿作用与成矿系统(华南中生代陆内成矿作用) • 上一篇    下一篇

热液成矿系统构造控矿理论

杨立强1,2,3,4(), 杨伟1, 张良1, 高雪1, 申世龙1, 王偲瑞1,5, 徐瀚涛1, 贾晓晨1,4, 邓军1,2,3,4   

  1. 1.中国地质大学(北京) 地质过程与矿产资源国家重点实验室/深时数字地球前沿科学中心, 北京 100083
    2.山东省地质科学研究院 自然资源部金矿成矿过程与资源利用重点实验室, 山东 济南 250013
    3.山东黄金地质研究院, 山东 济南 250101
    4.山东省地质矿产勘查开发局 第六地质大队 自然资源部深部金矿资源勘查与开采技术创新中心, 山东 威海 264209
    5.西昌学院 资源与环境学院, 四川 西昌 615000
  • 收稿日期:2023-11-07 修回日期:2023-12-21 出版日期:2024-01-25 发布日期:2024-01-25
  • 作者简介:杨立强(1971—),男,教授,博士生导师,主要从事矿床学及矿产普查与勘探的教学和科研工作。E-mail: lqyang@cugb.edu.cn
  • 基金资助:
    国家自然科学基金项目(42130801);国家自然科学基金项目(42272071);科学技术部国家重点研发计划项目(2019YFA0708603);高等学校学科创新引智计划2.0(BP0719021);中国地质大学深时数字地球前沿科学中心“深时数字地球”中央高校科技领军人才团队项目(2652023001);地质过程与矿产资源国家重点实验室专项(MSFGPMR201804)

Developing structural control models for hydrothermal metallogenic systems: Theoretical and methodological principles and applications

YANG Liqiang1,2,3,4(), YANG Wei1, ZHANG Liang1, GAO Xue1, SHEN Shilong1, WANG Sirui1,5, XU Hantao1, JIA Xiaochen1,4, DENG Jun1,2,3,4   

  1. 1. State Key Laboratory of Geological Processes and Mineral Resources/Frontiers Science Center for Deep-time Digital Earth, China University of Geosciences (Beijing), Beijing 100083, China
    2. Ministry of Natural Resources Key Laboratory of Gold Mineralization Processes and Resources Utilization, Shandong Institute of Geological Sciences, Jinan 250013, China
    3. Institute of Geological Research, Shandong Gold Group Co., LTD, Jinan 250101, China
    4. Ministry of Natural Resources Technology Innovation Center for Deep Gold Resources Exploration and Mining, No.6 Geological Team of Shandong Provincial Bureau of Geology and Mineral Resources, Weihai 264209, China
    5. College of Resources and Environment, Xichang University, Xichang 615000, China
  • Received:2023-11-07 Revised:2023-12-21 Online:2024-01-25 Published:2024-01-25

摘要:

构造对成矿的控制是热液成矿系统的典型特征之一,系统剖析多重尺度控矿构造的几何学、运动学、动力学、流变学和热力学对认识矿床成因和预测找矿至关重要;而如何实现控矿构造格架、渗透性结构、成矿流体通道和矿化变形网络由静态到多尺度时-空四维动态的转变,查明流体通道和矿床增量生长过程与控制因素,揭示热液成矿系统的构造-流体耦合成矿机制和定位规律是亟待解决的关键科学难题。为此,我们在对已有相关成果系统梳理的基础上,提出了科学构建热液成矿系统构造控矿理论的基本要点与对应方法及应用范畴:(1)流体而非构造是构造控矿理论的中心,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,其中渗透率是将流体流动与流体压力变化联系起来理解控矿构造的核心;(2)不同控矿构造组合的关键控制是构造差应力和流体压力的大小,而矿化类型的变化可能是由于构造应力场引起的容矿构造方位的不同和赋矿围岩之间的强度差异所致;(3)流体通道的生长始于超压流体储库上游围岩中孤立的微裂隙沿流体压力梯度最大的方向、随裂隙发育且相互连结而形成新的长裂隙,并最终连通形成断裂网络内的流体通道,矿床的增量生长发生在高流体通量的短爆发期,断层反复滑动驱动其内流体压力、流速和应力快速变化,当由此诱发的流体通道生长破坏了流体系统的动态平衡时,随之而来的流体快速降压就成为金属沉淀成矿的关键驱动因素;(4)以热液裂隙-脉系统野外地质观测和构造-蚀变-矿化网络三维填图为基础,通过宏观与微观各级控矿构造相结合、地质历史与构造应力分析相结合、局部与区域点-线-面相结合、浅部与深部相结合、时间与空间相结合、定性和定量相结合,对各种控矿因素开展多学科、多尺度、多层次、全方位综合研究,是应遵循的基本原则;(5)通过构造-蚀变-矿化网络填图,将蚀变-矿化体与控矿构造的类型、形态、规模、产状和间距等几何学特征联系起来,利用热液裂隙-脉系统和断裂网络拓扑学及矿体三维几何结构分析等定量方法查明控矿构造格架和渗透性结构并揭示矿化变形网络的连通性与成矿潜力;(6)合理构建地质模型,选取合适的热力学参数和动力学边界条件,利用HCh和COMSOL等方法,定量模拟成矿过程中的流体流动、热-质传递、应力变形和化学反应等的时-空变化,是揭示构造-流体耦合成矿机理和定位规律、预测矿化中心和确定找矿目标的有效途径。进而提出了构造控矿理论的研究流程:聚焦构造-流体耦合成矿机制和定位规律这一关键科学问题,选择热液裂隙-脉系统和构造-蚀变-矿化网络为重点研究对象;通过几何学描述、运动学判断、流变学分析、动力学解析和热力学综合,厘定控矿构造格架,定位矿化中心,示踪成矿流体通道和多种矿化样式的增量生长过程及其关键控制,揭示渗透性结构的时-空演变规律及构造再活化与成矿定位的成因关联,建立构造-流体耦合成矿模式,服务新一轮战略找矿突破。以胶东焦家金矿田为例,开展控矿构造理论研究和成矿预测应用实践,证实了其科学性和有效性。

关键词: 热液裂隙-脉系统, 构造-蚀变-矿化网络, 渗透性结构与成矿定位, 流体通道和矿床增量生长, 构造-流体耦合成矿模式

Abstract:

A defining feature of a hydrothermal metallogenic system (HMS) is strong structural control on ore mineralization. A systematic analysis of the geometry, kinematics, thermodynamics, and rheology of multiscale ore control structures is crucial for understanding the genesis of HMSs and for ore prospecting. The main challenges include: transitioning from static to multiscale spatiotemporal analysis of the 4D dynamical system involving ore-control structural frameworks, permeability structures, ore-forming fluid pathways, and mineralization deformation networks; identifying key influencing factors of fluid pathways that control ore deposition; and unraveling the mechanism of structure-fluid coupling control of ore formation and localization. This study presents the theoretical and methodological principles and application for developing structural control models for HMSs in the following aspects. (1) The theoretical core. It states that fluid, not structure, is at the core of a structural control model. Fluid flow and ore formation within a hydrothermal system are influenced by the fault zone architecture and permeability structure, where permeability, in linking fluid flow and fluid pressure variation, is key to understanding ore control structures. (2) Stress and pressure dynamics. It considers that differential stress and fluid pressure difference result in diverse combinations of ore control structures, while differences in regional stress field and host rock strength result in variations in mineralization type. (3) Growth of fluid pathways. It considers that fluid pathways initiate from isolated microfractures within the upstream host rocks of overpressured fluid reservoirs which evolve along the direction of the steepest pressure gradient to form new extended fractures through growth and interconnection. These extended fractures eventually interconnect to form fluid pathways. As ore deposition takes place during brief periods of high fluid flux when repeated fault sliding induces rapid changes in fluid pressure, flow velocity, and stress, rapid pressure release—caused by a disruption of dynamic equilibrium in the fluid system due to fluid pathways growth—is a key factor driving metal precipitation. (4) Integrated research. Methodology involves integrating macro and microscopic examination of ore control structures, integrating geological history and stress analysis, combining local and regional analyses, adopting shallow and deep perspectives, and employing a multidisciplinary, multiscale approach to study various ore-controlling factors. (5) Geological mapping. Methodology involves using structure-alteration-mineralization network mapping to characterize alteration-mineralization rock blocks in terms of geometric parameters for ore control structures (such as type, shape, size, occurrence, spacing), and performing quantitative analyses (such as topological analysis of hydrothermal vein-fracture systems, 3D geometric analysis of ore bodies) to determine ore-control structural frameworks and permeability structures and reveal the connectivity of mineralization deformation networks and their ore-forming potential. (6) Numerical modeling. Methodology involves developing geological models, selecting appropriate thermodynamic parameters and dynamic boundary conditions, and utilizing methods such as HCh and COMSOL to perform quantitative simulation of spatiotemporal variations in fluid flow, heat-mass transfer, stress deformation, and chemical reactions during ore formation. This is an effective approach to unveil the mechanism of ore formation controlled by structure-fluid coupling and ore localization pattern, predict ore-forming centers, and identify mineral exploration targets. Based on the above principles, this paper proposes a research methodology for model building, focusing on deriving metallogenic models and ore deposition patterns based on structure-fluid coupling control. Briefly, hydrothermal veins-fracture systems and structure-alteration-mineralization networks are selected as primary research subjects. Research methods include geometric description, kinematic assessment, rheological/dynamic analyses, and thermodynamic synthesis, seeking to delineate ore-control structural frameworks, identify mineralization centers, trace the developments of ore-forming fluid pathways and various mineralization styles, and reveal the spatiotemporal evolution patterns of permeability structures. Additionally, the causal relationship between tectonic reactivation and ore localization is explored. Finally, a metallogenic model based on structure-fluid coupling is constructed to support strategic mineral exploration. This research methodology was applied for mineral prediction in the Jiaojia gold field, Jiaodong Peninsula; its validity and effectiveness were tested and approved.

Key words: hydrothermal fracture and vein system, structure-alteration-mineralization network, permeability structure and mineralization localization, incremental growth of fluid pathway and ore deposits, a metallogenic model based on structure-fluid coupling

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