摘要
海南石碌多因复成Fe-Cu-Co矿床具有成矿规模大、品位高且伴生组分多等特点。虽然石碌矿区的铁矿石具有苏必利尔型条带状铁建造的成矿特征,但其中部分铁矿石并不呈现该类型铁建造常有的正Eu异常特征。本文通过分析北一和枫树下两个矿体中具有负Eu异常(Eu/Eu^(*)=0.47~0.74)铁矿石样品的主、微量元素特征,推测高温条件下高水-岩比的变质作用导致石碌矿区铁矿石的Eu异常发生正异常向负异常的转变。同时,利用LA-ICP-MS测定了铁矿石中磁铁矿和石榴子石的微量元素组成。基于磁铁矿中Ca+Al+Mn及Ti+V等元素含量特征,本文认为高盐度、高氧逸度的热液与磁铁矿中的负Eu异常(Eu/Eu^(*)=0.28~5.68)密切相关。另一方面,石榴子石的地球化学特征显示其具有同期同源的热液钙铁榴石属性,且形成石榴子石的热液具有高盐度、高CO_(2)浓度和偏碱性的特征。综合区域构造演化序列,本研究揭示了石碌矿床原始沉积的贫矿在240~210 Ma期间的韧性剪切构造下受到富CO_(2)盆地卤水的叠加改造,最终形成具有负Eu异常特征的富铁矿。
The Shilu polygenetic Fe-Cu-Co deposit in Hainan Province represents a large-scale,high-grade mineralization system with multiple associated components.Although containing components classified as Superior-type banded iron formation(BIF),some iron ores in the Shilu deposit lack the characteristic positive Eu anomalies typical of such BIFs.This study examines ore samples with negative Eu anomalies(Eu/Eu^(*)=0.47~0.74)from the Beiyi and Fengshuxia deposits.We propose that high-temperature metamorphism under high water-rock ratio conditions induced abnormal Eu behavior in these ores.LAICP-MS analysis of magnetite and garnet trace elements reveals that hydrothermal magnetite exhibits variable Eu anomalies(Eu/Eu^(*)=0.28~5.68),with Ca+Al+Mn and Ti+V compositions suggesting a strong correlation between Eu anomalies and fluid properties.Furthermore,rare earth element(REE)patterns of coeval hydrothermal andradite garnet,combined with regional data,indicate that the formation of negative Eu-anomalous Fe-Cu-Co mineralization involved two key processes during the Shilu ore fields enrichment period(240~210 Ma):shear deformation caused by massive granite intrusion and hydrothermal modification of pre-existing ores by heated basin brines(characterized by high salinity,elevated CO_(2)content,and alkaline conditions).These processes collectively contributed to the deposits final enrichment.
作者
胡天杨
刘家豪
刘磊
张创业
李家掀
刘恒
HU Tianyang;LIU Jiahao;LIU Lei;ZHANG Chuangye;LI Jiaxian;LIU Heng(Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring,Ministry of Educationin,Central South University,Changsha,Hunan 410083,China;School of Geosciences and Info-Physics,Central South University,Changsha,Hunan 410083,China;Henan Institute of Ultrapure Mineral Materials,Zhengzhou,Henan 450016,China;Henan Academy of Geology,Zhengzhou,Henan 450016,China;Hainan Provincial Department of Natural Resources and Planning,Haikou,Hainan 570204,China;State Key Laboratory of Critical Mineral Research and Exploration,Central South University,Changsha,Hunan 410083,China)
出处
《地质学报》
北大核心
2025年第8期2761-2777,共17页
Acta Geologica Sinica
基金
国家自然科学基金项目(编号41972198)
湖南省科技创新团队项目(编号2021RC4055)
湖南省自然科学基金项目(编号2022JJ30702)
湖南省研究生科研创新项目(编号CX20220167)
国家留学基金委项目(编号202206370119)联合资助的成果。
