江西赣县大埠钨多金属矿田成岩成矿时空结构与找矿预测  

Spatio-temporal structure and prospecting of Dabu tungsten polymetallic ore field,Ganxian,Jiangxi Province

作　　者：郭德银 赵正[1] 侯占德 陶建利 尹积扬 段超[1] GUO DeYin;ZHAO Zheng;HOU ZhanDe;TAO JianLi;YIN JiYang;DUAN Chao(MNR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China;The Seventh Geological Brigade of Jiangxi Bureau of Geology,Ganzhou 341000,Jiangxi,China)

机构地区：[1]中国地质科学院矿产资源研究所自然资源部成矿作用与资源评价重点实验室,北京100037 [2]江西省地质局第七地质大队,江西赣州341000

出　　处：《矿床地质》2024年第3期578-598,共21页Mineral Deposits

基　　金：国家重点研发计划项目(编号:2022YFC2905101);国家自然科学基金(编号:41973046);中国地质调查局地质调查项目(编号:DD20190713)联合资助。

摘　　要：大埠矿田位于南岭成矿带东段,是于都-赣县钨多金属矿集区重要组成,区内已发现钨多金属矿床(点)五十余处,矿床类型包括石英脉型、矽卡岩型、云英岩型和细脉浸染型等,各类矿化主要围绕大埠复式花岗岩体产出。然而,大埠矿田岩浆作用具有明显的多期次、多阶段的特点,各期次成岩成矿时代尚缺乏系统研究,各类岩浆岩与矿化关系争议较大。文章在岩体地质和矿床地质调查基础上,通过LA-(MC)-ICP-MS锆石U-Pb定年、锆石微量元素和Hf同位素分析,精确厘定了大埠花岗岩的成岩时代,探讨了多期次岩浆活动对区内成矿作用的贡献。锆石U-Pb定年结果分别为(429.1±4.7)Ma、(430.0±5.8)Ma、(431.8±4.7)Ma和(158.3±4.1)Ma,结合岩体地质填图信息,笔者认为大埠复式花岗岩基由加里东期和燕山期两部分组成。两期花岗岩均属于高钾钙碱性、过铝质S型花岗岩系列,两者均出现Eu负异常,燕山早期Eu负异常更明显。两期岩体锆石的ε_(Hf)(t)值分别为-6.3~-1.3与-11.4~-7.1,对应二阶段模式年龄为1.49~1.82 Ga与1.66~1.93 Ga,指示其母岩浆为中元古代的地壳部分熔融形成。锆石微量元素特征显示,两期花岗岩均为陆壳源区、具有相近的结晶温度,燕山早期花岗岩相对于加里东期有更高的结晶分异程度,有更高的氟含量,与钨成矿具有更强的相关性。大埠矿田钨多金属成矿时代集中在159~155 Ma,紧随燕山早期花岗质岩浆侵位而形成。基于大埠矿田成岩成矿时代格架研究,结合花岗岩成矿专属性和成矿地质条件分析,构建了区内钨多金属矿勘查模型,指明了大埠矿田细脉浸染型、云英岩型、内带石英脉型钨矿的找矿方向,预测大埠岩体东北部的燕山早期隐伏岩体具有寻找“合龙式”石英大脉型和细脉-云英岩型钨矿的潜力。The Dabu ore field,located in the eastern part of the Nanling metallogenic belt,is an important component of the Yudu-Ganxian tungsten polymetallic ore cluster,where more than 50 tungsten polymetallic deposits/occurrences have been discovered,including quartz vein type,skarn type,greisen type and veinlet-disseminated type.All kinds of mineralization are distributed around the Dabu granitic complex.The Dabu complex has characteristics of multiple phases stages based on the field observation,which,however,lacks systematic research,especially on the relationship between various phases stages of magmatism and different types of mineralization.In this study,zircon grains from different phases of the Dabu complex were dated by LA-(MC)-ICP-MS to constrain the time framework of magmatism.Dating results are(429.1±4.7)Ma,(430.0±5.8)Ma,(431.8±4.7)Ma and(158.3±4.1)Ma,showing two groups of ages in Caledonian and early Yanshanian.Furthermore,trace elements and Hf isotopes were analyzed,showing that both the two phases of granits belong to the high-K,calc-alkaline and peraluminous,S-type granites.In detail,the Eu negative anomaly is more obvious in the early Yanshanian phase than that of the Caledonian phase.Theε_(Hf)(t)values of zircon grains from the Caledonian and Yanshanian phases are-6.3~-1.3 and-11.4~-7.1,respectively,corresponding to the two-period model ages of 1.49~1.82 Ga and 1.66~1.93 Ga,indicating that the parent magma was formed by partial melting of the crust during Mesoproterozoic.The trace element characteristics of zircon show that both Caledonian and Yanshanian phases had continental crust source regions and had similar crystallization temperatures.But the early Yanshanian phase has a higher degree of crystallization differentiation and higher F content and has a stronger correlation with tungsten mineralization than that of the Caledonian phase.Our study indicates that the tungsten mineralization in the Dabu ore field are concentrated in 159~155 Ma,which was formed immediately after the emplacement of th

关 键 词：锆石 勘查模型 大埠花岗岩 燕山期 钨多金属矿床 

分 类 号：P618.42[天文地球—矿床学]