摘要
开展铜、锂和铍等关键金属的迁移富集机制与规律研究对于理解斑岩型和伟晶岩型矿床的成因具有重要意义。目前,大多数研究集中在岩浆形成到热液析出的“两端”演化过程,而岩石的后期热液蚀变是流体活动最活跃的时期,会强烈改造前期的成矿过程,导致难以识别岩浆向热液转换阶段的成矿流体演化特征。近来,研究发现花岗质岩浆在岩浆‒热液过渡阶段存在熔体与热液流体共生的岩石学记录:斑岩型矿床成矿体系中保存的含矿岩墙/脉、富铜钼的“岩浆‒流体”囊状体、“羽丝状”含矿细晶岩脉群、蠕虫状石英斑晶中保留的熔体‒流体包裹体;伟晶岩型矿床成矿体系中保存的单向固结的石英脉和细晶岩、晶洞构造和文象结构等。这些岩石学证据有效记录了成矿流体从岩浆到热液演化过程中同源固相与流体相之间的平衡控制过程,以及成矿元素的溶解和富集行为:(1)岩浆‒热液过渡阶段形成的“羽丝状”含铜细晶岩脉群,表明在较高的温度(523~613)℃条件下,熔体和流体存在相分离;(2)岩浆‒热液过渡阶段形成的熔流体混合相是亲铜元素由岩浆迁移进入热液的保障,可能代表了运移成矿元素介质的性质;(3)在岩浆‒热液过渡阶段,晶洞中石英的阴极发光(CL)图像揭示了多期环带结构,不同环带的O同位素均显示来源于岩浆阶段,可能与同一岩浆房中存在成矿流体多次出溶相关;(4)岩浆‒热液过渡阶段分离出的碱性金属元素/挥发性组分(如H2O、F、B和Cl)进一步促进了伟晶岩型矿床中Li、Be等成矿金属的富集和迁移;(5)岩浆‒热液过渡阶段形成的特殊含矿结构(如文象结构)是伟晶岩型Be矿床的有效找矿标志。在岩浆‒热液过渡阶段形成的岩石学证据虽然受到后续热液的强烈改造,但是仍能保存部分重要的成矿学信息,剖析该阶段成矿作用有助于了解花岗质成矿岩�
Investigation of the migration and enrichment mechanisms of key metals such as copper,lithium,and beryllium is of significant importance to understand the genesis of porphyry and pegmatite deposits.Currently,most research focuses on the‘endpoints’of magmatic formation and hydrothermal precipitation,whereas much less attention has been paid to the later stages of hydrothermal alteration.The extremely intensive fluid activity during these stages can significantly alter the preceding mineralization processes,making it challenging to identify the crucial original ore-forming fluids.As a result,our understandings of the complete ore-forming process from magmatic to hydrothermal transitions was greatly limited.Recent research has indicated that there are unique interactions between granite magmas and aqueous hydrothermal fluids during the granite magma-hydrothermal fluid transition.Certain“precious”petrological records seem to preserve evidence and evolutionary information related to this process.These observations reflect equilibrium between the solid and fluid phases of ore-forming fluids during the magmatic to hydrothermal evolution process.They also shed light on the dissolution and enrichment behavior of ore-forming elements.Examples of such evidence include ore-bearing wall veins in porphyry systems,copper-molybdenum-rich“magma-fluid”cavities,“feather-like”ore-bearing fine-grained vein networks,melt-fluid inclusions preserved in worm-like quartz phenocrysts,unidirectional solidification textures(UST)in quartz and fine-grained rocks,crystal cavity structures,and textural features in pegmatite systems.A further summary of findings includes the following:(1)The formation of the“feather-like”ore-bearing fine-grained vein networks during the magmatic-hydrothermal transition,indicating phase separation between melt and fluid at elevated temperatures(523–613),℃which plays a pivotal role in copper migration and enrichment in porphyry copper deposits;(2)Fluid-melt or fluid-magma formed during the m
作者
洪涛
翟明国
高俊
徐兴旺
吴楚
HONG Tao;ZHAI Mingguo;GAO Jun;XU Xingwang;WU Chu(Guangdong Provincial Key Laboratory of Geodynamics and Geohazards,School of Earth Sciences and Engineering,Sun Yat-sen University,Zhuhai 519082,Guangdong,China;Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai 519082,Guangdong,China;Key Laboratory of Mineral Resources,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;University of Chinese Academy of Sciences,Beijing 100049,China;Innovation Academy for Earth Science,Chinese Academy of Sciences,Beijing 100029,China;Development and Research Center,China Geological Survey,Beijing 100037,China)
出处
《大地构造与成矿学》
EI
CAS
CSCD
北大核心
2024年第3期460-477,共18页
Geotectonica et Metallogenia
基金
国家自然科学基金原创探索项目(42250202)
国家自然科学基金面上项目(42272075)
自然科学基金重大研究计划集成课题(92162323)
广东省自然科学基金面上项目(2022A1515010003)联合资助。
