【作者】 王中亮；

【导师】 杨立强；

【作者基本信息】 中国地质大学(北京) ， 矿物学、岩石学、矿床学， 2012， 博士

【摘要】 焦家金矿田是焦家式金矿命名地，已查明黄金资源/储量500余吨，其金矿床产出环境和成矿动力学背景在全球金矿中独具特色，巨量金的来源和富集机制是引人瞩目关键科学问题。论文聚焦该金矿田成矿系统，通过详细的野外和室内研究，获得如下主要成果。1、金矿形成于陆-陆碰撞向俯冲碰撞构造体制转换过程中岩石圈大规模减薄的地球动力学背景，成矿期区域主压应力为NNE-NE向，控矿断裂带以右行张剪活动为主。焦家断裂带及其下盘次级断裂、裂隙构成菱形控矿断裂系统，控制矿化网络的形成与分布。2、蚀变-矿化岩石与玲珑黑云母花岗岩及胶东群变质岩具继承性，且后两者中金品位与矿床规模成反比；煌斑岩的地质-地球化学特征与矿石具有明显差异，其金丰度与其所侵入的地质体的金丰度成正比，煌斑岩规模与金矿床规模成反比；表明金可能来源于玲珑黑云母花岗岩和胶东群变质岩，而煌斑岩不提供成矿物质。3、成矿流体主体为中-低温（200℃～330℃）、低盐度（3.15～8.99wt%NaCl）的H₂O-CO₂-K⁺-Cl^-体系，H、O同位素组成大多与变质/岩浆流体一致。成矿过程中，载金黄铁矿稀土元素总量呈现先增后降趋势，流体中δ¹⁸O值逐渐降低；暗示成矿流体主体来源于变质流体，而变质程度和水-岩反应可能是影响金沉淀的主因。4、金矿化3D分带结构特征明显：水平方向上，从焦家主断裂下盘向外由破碎带蚀变岩型→钾化细脉浸染型→石英硫化物脉型矿化变化；垂向上，矿床尺度总体为蚀变岩型矿化在上、脉型矿化在下，矿体尺度往往是脉型矿化在上、蚀变岩型矿化在下。成矿后的风化剥蚀是影响金矿床变化保存主要因素，在焦家断裂带内金矿床的剥蚀深度由NE→SW依次增大，望儿山断裂带内金矿床的剥蚀深度浅于焦家断裂带内金矿床的剥蚀深度。5、金矿田是构造-流体耦合成矿产物：流体沿控矿断裂走向运移的同时，由于周期性压力积聚引起裂隙向外扩展，部分流体侧向运移。流体与围岩发生交代反应，使含矿流体由碱性氧化高温→酸性弱还原中-高温→弱酸性还原中-低温演化，导致围岩中金成为高价态离子活化进入流体，之后物理化学条件改变，引起流体中AuH₃SiO₄和AuHSiO₄稳定性降低、[AuCl₂]^-和Au（HS）₂^-的溶解度减小，Fe²⁺、Fe³⁺、Cu²⁺等金属离子被消耗形成黄铁矿、黄铜矿等金属硫化物，造成金-硫/氯络合物分解，导致金大量沉淀聚集成矿。6、以成矿系统结构为基础，构建勘查系统模型，指出焦家断裂下盘距主断裂面1000m范围内具有良好找矿前景。针对重点远景区，进一步建立隐伏矿体预测模型，圈定20处预测靶位。截止2011年底，经矿山工程验证累计探明新增金金属量10.04t。更多还原

【Abstract】 Jiaojia gold field is the nomenclature spot of the Jiaojia-type gold deposits, withidentified gold resources/reserves of over 500 tonnages. The tectonic setting andmetallogenic geodynamic setting of Jiaojia gold field is unique among the global golddeposits, and the source and enrichment mechanism of huge gold resources areattractive key scientific problems. The thesis focuses on the metallogenic system ofJiaojia gold field, and the following conclusions were made through detailed field andlaboratory research.1. The gold deposit formed in the geodynamic setting of large-scale lithospherethinning during tectonic regime transformation from continent-continent collision tosubduction collision. The regional principal compressive stress in the ore stage isNNE-NE striking, and the ore-controlling fault belt is dominated by dextral tensoshear activities. The rhombic ore-controlling fault system, which is composed ofJiaojia fault belt and secondary faults and fractures on its footwall, controlls theformation and distribution of the mineralization network.2. Altered-mineralized rocks inherit from Linglong biotite granite andmetamorphic rocks of Jiaodong Group, and the gold grade in Linglong granite andJiaodong Group is inversely proportional to the deposit scale. Though lamprophyre islocated near the mineralization belt, its geological-geochemical characteristics areobviously distinct from those of ores, and its gold grade is directly proportional to thegold grade of geologic bodies that the lamprophyre intruded into, and the lamprophyre scale is inversely proportional to the deposit scale. In conclusion, thegold originates from Linglong biotite granite and metamorphic rocks of JiaodongGroup instead of lamprophyre.3. The ore fluid is a H2O-CO2-K+-C1-system which is of medium-lowtemperature (200℃-330℃), low salinity (3.15-8.99wt%NaCl), and similar isotopecompositions with metamorphic/magmatic fluids, with minor late-ore stage fluiddrifts to the meteoric water line. During metallogenic processes, the total content ofrare earth elements in the gold-bearing pyrite increases first and decreases afterwards,withδ18O in the fluids decreases gradually, indicating that the ore fluid mainlyoriginates from metamorphic fluid, while the metamorphic grade and water-rockreaction are the main factors that affect gold deposition.4. The 3D zonation structure of gold mineralization is evident. In horizontaldirection, away from the main fault plane on the footwall of Jiaojia fault, themineralization varies from pyrite-sericite-quartz altered rocks mineralization toquartz-sulfides veins -pyrite-sericite-quartz altered rocks- silicified rocksmineralization. In vertical direction, the altered rocks mineralizations overlie the veintype mineralizations in deposit scale, while the vein type mineralizations overlie thealtered rocks mineralizations in ore body scale. Weathering and denudation aftermineralization are the main factors affecting the transformation and preservation ofgold deposits. The denudation depth increases from NE to SW of the Jiaojia fault, andthe denudation of Wangershan gold ore bodies is shallower than that of Jiaojia goldore bodies.5. Gold field is the product of structure-fluid coupling ore formation. The fluidsmigrated along the strikes of ore-controlling faults, meanwhile, due to the outwarddevelopment of fractures caused by accumulation of periodic pressure, part of thefluids migrated laterally. The changing of ore fluids from alkaline-oxidative-hightemperature fluids to acidic-weak reductive-medium-high temperature fluids to weakacidic-reductive-medium-high temperature fluids made the gold in host rocks becomehighly charged ions, reactivate and flow into fluids. Afterwards, the changes ofphysical-chemical conditions caused the stability decrease of AuH3SiO4and AuHSiO4, the solubility decrease of [AuCl2]-and Au(HS)2-, the consumption of Fe2+、Fe3+、Cu2+,the formation of pyrite, chalcopyrite and other sulfides, the break down ofgold-sulfur/chlorine complex compound, and accumulation and deposition of hugegold resources.6. Exploration system model was established according to the analysis results ofspace-time structure of metallogenic system and prospecting potential at the footwallwas pointed at areas of 500~1000m away from the Jiaojia fault. Aiming at theimportant prospecting potential areas, prediction model of blind ore body wasestablished and 20 prediction targets were defined. A total proved newly increasedgold resource is 10.04t by the end of the year of 2011.更多还原