广东河台金矿围岩磁组构特征、年代学及与金矿化关系  

Geochronology, Magnetic Fabric of Rocks and its Relationship with Ore Mineralization in Hetai Goldfield, Guangdong Province

作　　者：王历星 许可[4] 许德如 陈根文[3] 朱昱桦 蔡建新[6] 焦骞骞 WANG Lixing;XU Ke;XU Deru;CHEN Genwen;ZHU Yuhua;CAI Jianxin;JIAO Qianqian(Key Laboratory of Marine Mineral Resources,Ministry of Natural Resources,Guangzhou 510760,Guangdong,China;Guangzhou Marine Geological Survey,Guangzhou 510760,Guangdong,China;Key Laboratory of Mineral and Metallogeny,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,Jiangxi,China;Guizhou Geological Survey,Guiyang 550081,Guizhou,China;Key Laboratory of Ocean and Marginal Sea Geology,South China Sea Institute of Oceanology,Chinese Academy of Sciences,Guangzhou 510301,Guangdong,China;Faculty of Land Resources Engineering,Kunming University of Science and Technology,Kunming 650093,Yunnan,China)

机构地区：[1]自然资源部海底矿产资源重点实验室,广东广州510760 [2]广州海洋地质调查局,广东广州510760 [3]中国科学院广州地球化学研究所矿物学与成矿学重点实验室,广东广州510640 [4]东华理工大学核资源与环境国家重点实验室,江西南昌330013 [5]贵州省地质调查院,贵州贵阳550081 [6]中国科学院南海海洋研究所边缘海与大洋地质重点实验室,广东广州510301 [7]昆明理工大学国土资源工程学院,云南昆明650093

出　　处：《大地构造与成矿学》2019年第6期1169-1185,共17页Geotectonica et Metallogenia

基　　金：国家自然科学基金重点项目(41930428);国家重点研发计划项目(2016YFC0600401)联合资助

摘　　要：河台金矿田是目前粤西、桂东南已发现最大的金矿田,大部分矿体产出在剪切带糜棱岩中,是典型的与剪切带有关的金矿床。在构造研究上,前人只注重糜棱岩的构造分析工作,而忽视了同样作为矿体围岩的混合花岗岩和片岩的研究。目前为止,矿体围岩的形成时代、变质变形特征以及与成矿之间的关系尚不清楚。我们在野外观测、显微构造分析的基础上,对河台金矿的混合花岗岩和片岩展开了磁组构分析工作。岩石磁组构分析结果显示:样品的平均磁化率Κm值总体较小,顺磁性矿物主导了样品的磁组构;磁化率各向异性度P值均>1.04,范围在1.044~1.648之间;磁化率椭球体形状参数T总体>0;扁率E值多>1,或接近于1;在弗林图解中,数据主要集中在压扁区,少部分有剪切特征;混合花岗岩最小磁化率轴的方位表明岩石受到的主压应力呈NNW-SSE或近S-N向;片岩的磁面理呈NE向,磁线理呈NW或NNW向近水平,反映岩石受到左行走滑导致的挤压或者韧性拉长变形的特征。磁组构特征总体反映出河台地区的岩石磁化率椭球体以压扁型为主,磁面理较磁线理发育,经历了较强烈的近SN向弥散性的挤压作用和局部韧性剪切变形。此外,河台金矿的混合花岗岩LA-ICP-MS锆石U-Pb年龄为251.7±1.7 Ma。在成矿过程中,岩石校正后的磁各向异性度Pj值与金属元素Au、Cu含量呈弱的负相关关系,说明岩石矿化蚀变作用晚于构造变形作用。结合各岩石的宏观片理、显微构造和前人的年代学工作,推测河台地区地质事件的早晚顺序依次是混合岩化→剪切变形→金矿形成。The Hetai goldfield,one of the largest gold mining districts in South China,is located in Gaoyao country,western Guangdong province.The Hetai is a typical shear zone related gold deposit and most of the orebodies are hosted in mylonites within the shear zone.Previous tectonic studies mostly focused on tectonic analysis of mylonite,while other host rocks such as migmatitic granite and schist are largely ignored.The formation age,metamorphism and deformation characteristics of the host rocks remain unclear.Based on field observations and microstructural analysis,we carried out magnetic fabric analysis on the migmatitic granite and schist in the Hetai goldfield.Magnetic fabric analysis showed that the averageΚm of magnetic susceptibility value is rather small,and paramagnetic minerals play a dominant role in the formation of the magnetic structure;all anisotropy of magnetic susceptibility P values are greater than 1.04,ranging from 1.044 to 1.648;the shape parameters T of magnetic susceptibility ellipsoid are commonly greater than 0;E values of flattening are greater than 1,or close to 1;in Flinn plot,the data are mainly concentrated in the oblate area,with a few shear features;the orientation of the minimum susceptibility axis of the migmatitic granite indicates that the direction of principal compressive stress is NNW-SSE or near S-N.The magnetic foliation of the schist is NE,and the magnetic lineation is generally NW or NNW of nearly horizontal.These characteristics imply that the schist suffered extrusion or ductile elongated deformation caused by the sinistral slip.Magnetic fabric features reflect the rocks in the Hetai area have flatten type susceptibility ellipsoid,and the magnetic foliation is better developed than magnetic lineage.The rocks experienced a moderate intense near-SN penetrative extruding and local ductile shear deformation.LA-ICP-MS U-Pb dating of zircon from the migmatitic granite in the Hetai goldfield yielded an age of 251.7±1.7 Ma.The weak negative correlation between rock magnetic anisot

关 键 词：河台金矿 磁组构 构造控矿分析 锆石U-PB年龄 

分 类 号：P612[天文地球—矿床学]