摘要
热液矿床中,矿体(群)的侧伏规律是构造−流体耦合成矿系统在三维空间的具体表现,但确定其侧伏向和侧伏角一直是找矿预测的难题之一。文章聚焦矿体(群)侧伏规律及其力学机制研究中存在的主要问题(多期构造叠加造成的矿体侧伏识别难、矿体群侧伏控制机制不清、深部矿体侧伏模型实证研究不足等),基于矿田地质力学理论与方法,突破多期构造识别、矿体群侧伏控制机制等瓶颈,研究总结了压扭性、张扭性/扭张性、剪切带/扭性为主断裂带及复合构造控制的矿体(群)的侧伏规律,并解析其力学机制,提出矿体(群)侧伏确定方法。研究表明,成矿断裂构造的力学、运动学及其倾向、倾角共同控制矿体(群)侧伏产状,其侧伏向与成矿断裂下降盘运动方向一致,侧伏角受成矿构造应力场水平分量或成矿构造运动方向与断裂走向夹角的大小控制;不同级序构造控制的矿体群与单个矿体的侧伏规律不完全一致。在此基础上,认为成矿构造解析、矿化蚀变分带趋势追索、矿柱中心点投影及勘查工程数据三维空间分析是推断隐伏矿体(群)侧伏的主要方法,构造地球化学和地球物理异常分析等方法,可显著提升深部隐伏矿体(群)侧伏预测的可靠性,有望打开深部找矿新局面,取得事半功倍之功效。该研究在指导矿山深部和外围找矿预测与勘查区矿产评价、优化勘查工程部署、深化热液矿床成矿动力学机制及准确估算资源储量等方面具有重要意义。
[Objective]Hydrothermal mineral deposits provide a representative example of tectonic–fluid coupled metallogenic systems,and the lateral plunge law of ore bodies or ore body clusters constitutes their three-dimensional expression in geological space,yet the determination of pitching direction and pitching angle has long been one of the most difficult problems in prospecting prediction.[Methods]This study aims to address the major challenges in understanding plunge law and mechanical mechanisms,namely the difficulty of identifying ore body pitching under multiphase tectonic superposition,the lack of clarity in the control mechanisms of ore body cluster pitching,and the insufficiency of empirical studies on deep ore body pitching models.Based on Theory and Methods of Orefield Geomechanics,breakthroughs were achieved in multiphase structural recognition and the identification of control mechanisms,allowing systematic summarization of plunge law associated with compressional–shear,extensional–shear or transtensional,ductile shear zone or brittle shear belt,and composite structural controls,together with detailed analysis of their mechanical mechanisms and the proposal of practical methods for determining pitching.[Results]The results indicate that in hydrothermal deposits,ore body pitching is strictly controlled by the mechanical properties,kinematic behavior,and spatial configuration of the dominant ore-controlling structures during mineralization:the pitching direction of ore bodies or clusters is consistent with the movement of the hanging wall of the controlling fault,while the pitching angle is governed by the fault dip,the proportion of shear components,the undulatory amplitude of fault planes,and the orientation of the regional principal stresses.Ore bodies controlled by transpressional or transtensional faults exhibit more pronounced pitching than those associated with simple compressional–shear or extensional–shear structures;for single ore bodies or vein clusters,pitching direction may coincide with that of the cluster in transpressional or compressional–shear systems,or conversely oppose it in transtensional or extensional–shear systems;where ductile shear zones control mineralization,pitching is parallel to stretching lineations,while brittle shear belts produce pitching that follows extension-compression directions;in composite structural systems,the determination of pitching requires careful analysis of inherited,superimposed,or transformed tectonic elements to establish the effective mode of control.Mechanically,the pitching direction corresponds to the orientation of maximum permeability of metallogenic fluids within the ore-controlling stress field:in compressional-shear or transpressional faults,pitching is constrained by the sense of shear displacement;in transtensional faults,it is determined by the orientation of dominant fluid channels;and in ductile shear zones,it follows the X-axis of the strain ellipsoid.[Conclusion]These findings confirm that the mechanics and kinematics of ore-controlling structures are the primary factors dictating the occurrence of pitching in ore bodies and clusters,but they also highlight that the regularities differ between structural hierarchies,with the behavior of ore body clusters not entirely identical to that of single ore bodies,and that the observed patterns reflect the combined action of the metallogenic stress field,fluid dynamics,and the physical properties of host rocks.On this basis,several methods are recognized as effective for inferring the pitching of concealed ore bodies,including structural analysis of mineralizing faults,tracing zoning trends of mineralization and alteration,projection of ore column centroids,and three-dimensional spatial analysis of exploration engineering data,while the integration of structural geochemical and geophysical anomaly analyses can significantly enhance the reliability of pitching prediction in deep concealed settings,thereby opening new avenues for deep ore prospecting and achieving high efficiency in exploration.[Significance]The significance of this study lies not only in its practical applications-guiding deep and peripheral prospecting,improving mineral resource evaluation in exploration areas,optimizing the deployment of exploration projects,and enabling more accurate estimation of reserves-but also in its theoretical contributions,particularly in advancing the understanding of the metallogenic dynamics of hydrothermal deposits by linking structural mechanics,stress fields,fluid migration,and rock physical properties in a unified framework for explaining ore body pitching.
作者
韩润生
张艳
罗进
黄保胜
胡体才
HAN Runsheng;ZHANG Yan;LUO Jin;HUANG Baosheng;HU Ticai(Kunming University of Science and Technology,Kunming 650093,Yunnan,China;Southwest Geological Survey,Nonferrous Metals Minerals Geological Survey Center,Kunming 650093,Yunnan,China;Yunnan Chihong Zn&Ge Co.,Ltd.,Qujing 655099,Yunnan,China)
出处
《地质力学学报》
北大核心
2025年第5期886-897,共12页
Journal of Geomechanics
基金
国家自然科学基金项目(42172086,42472127)
云南省矿产资源预测与评价工程研究中心项目(2011)
云南省昆明理工大学创新团队项目(2012)。
关键词
矿体(群)侧伏规律
力学机制
侧伏确定方法
物化探异常分析
热液矿床
plunge law of ore bodies(cluster)
mechanical mechanisms
plunge determination methods
geophysical and geochemical anomaly analysis
hydrothermal deposits
