摘要
变质核杂岩是控制胶东地区金矿空间分布的关键地质因素之一。以往胶东地区金矿研究多集中于侵入岩体与成矿的关联性,而对侵入岩相关变质作用的关注不足,尤其缺乏对成矿流体变质热液属性的溯源研究,这在一定程度上制约了找矿方向的精准定位。本文以胶东地区上庄金矿为研究对象,通过系统的矿相学观察,并结合物化探异常解析及元素地球化学分析,以厘清该矿床变质作用条件,明确变质热液来源。矿相学研究结果显示,上庄金矿床内的花岗闪长岩经历了高绿片岩相变质作用,并叠加了低绿片岩相变质改造,这一特征暗示深部可能存在更高级别的变质相带,同时反映该变质杂岩体曾经历折返与隆升过程。此外,变质成因石英被细粒绢云母与石英交代的现象,表明成矿作用发生于最晚一期变质事件之后;黄铁绢英岩矿物组成简单,且绢云母含量较围岩显著增高,进一步佐证成矿流体具有变质热液属性。物化探与地球化学分析表明,视电阻率异常与矿化分布具有良好的对应关系,该矿床东南部深部的高阻异常揭示该区可能存在隐伏岩体,即变质核杂岩隐伏区段;原生晕Au、Bi、Mn等元素在焦家断裂上、下盘的含量差异显著,指示成矿流体主要来源于断裂下盘(东南盘)。垂向方向上,Au、Bi、Ag、Cu等成矿元素异常未封闭,显示矿化具有向深部延伸的趋势,但深部找矿工作需审慎推进。综合研究认为,上庄金矿东南部隐伏岩体分布区域是未来找矿勘查的重点靶区,具备发现新矿体的良好潜力。
Metamorphic core complexes represent one of the key geological factors controlling the spatial distribution of gold deposits in the Jiaodong Peninsula.Previous studies on gold mineralization in Jiaodong have predominantly focused on the relationship between intrusive rocks and mineralization,while paying less attention to the metamorphism associated with these intrusions.In particular,there has been a lack of systematic tracing of the metamorphic-hydrothermal origin of the ore-forming fluids,which has constrained the accurate targeting of exploration directions.This study takes the Shangzhuang gold deposit in Jiaodong as a case study.Through systematic petrographic observations,integrated with analysis of geophysical and geochemical anomalies and elemental geochemistry,we aim to clarify the metamorphic conditions and identify the source of metamorphic fluids.Petrographic results indicate that the granodiorite in the Shangzhuang deposit underwent high greenschist-facies metamorphism overprinted by low greenschist facies metamorphism.It is suggestive of possible transition to higher-grade metamorphic zones at depth and reflects a process of exhumation and uplift of the metamorphic complex.Furthermore,the replacement of metamorphic quartz by fine-grained sericite and quartz indicates that mineralization occurred after the latest metamorphic event.The simple mineral assemblage of pyrite-sericite-quartz rock(ore),with significantly higher sericite content compared to the wall rock,further supports the metamorphic-hydrothermal nature of the ore-forming fluids.Integrated geophysical and geochemical analyses reveal a strong correlation between apparent resistivity anomalies and mineralization.A highresistivity anomaly in the southeastern deep part of the deposit suggests the presence of a hidden intrusive body,i.e.,a concealed segment of the metamorphic core complex.Significant differences in the concentration of primary halo elements such as Au,Bi,and Mn between the hanging wall and footwall of the Jiaojia fault indicate that the ore-forming fluids were mainly derived from the footwall(southeastern block).In the vertical direction,the unclosed anomalies of ore-forming elements such as Au,Bi,Ag,and Cu suggest that the mineralization extends downward,though further deep exploration should be conducted cautiously.Comprehensive research indicates that the area with concealed intrusive rocks in the southeastern part of the Shangzhuang gold deposit is a key target for future exploration,with high potential for discovering new ore bodies.
作者
孙靖
周辉
王志浩
方立东
贾静
张启连
韦访
SUN Jing;ZHOU Hui;WANG Zhihao;FANG Lidong;JIA Jing;ZHANG Qilian;WEI Fang(Geological Exploration Institute of Shandong Zhengyuan,Jinan,Shandong 250014;Nanning University,Nanning,Guangxi 530200;Guangxi Institute of Geological Survey,Nanning,Guangxi 530023)
出处
《地质与勘探》
2025年第5期926-937,共12页
Geology and Exploration
基金
广西教育科学规划专项课题(编号:2023ZJY1454)资助。
关键词
变质核杂岩
变质热液
高绿片岩相
高阻异常
原生晕
找矿方向
上庄金矿
胶东地区
metamorphic core complex
metamorphic fluid
high greenschist facies
high resistivity anomaly
primary halo
exploration direction
Shangzhuang gold deposit
Jiaodong Peninsula
作者简介
第一作者:孙靖(1985年-),男,2007年毕业于桂林工学院,资源勘查工程专业,学士学位,高级工程师,主要从事地质勘查及科研工作。E-mail:13573698582@163.com;通讯作者:周辉(1985年-),男,2011年毕业于桂林理工大学,矿产普查与勘探专业,硕士学位,高级工程师,主要从事地质勘查、教学及科研工作。E-mail:zhouh@unn.edu.cn。
