冀东司家营BIF铁矿床磁铁矿类型与成因及其对高品位铁矿化成矿机制的启示  

Types and Genesis of Magnetite in the Sijiaying Banded Iron Formation-hosted Iron Deposit,Eastern Hebei Province:Insights into Mechanisms of High-Grade Iron Mineralization

作　　者：张美诺 石康兴 邱昆峰[1] 邓军[1] ZHANG Meinuo;SHI Kangxing;QIU Kunfeng;DENG Jun(School of Earth Sciences and Resources,China University of Geosciences(Beijing),Beijing 100083,China;College of Earth Sciences,Hebei GEO University,Shijiazhuang,Hebei 050031,China;Hebei Province Collaborative Innovation Center for Strategic Critical Mineral Research(Hebei GEO University),Shijiazhuang,Hebei 050031,China)

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083 [2]河北地质大学地球科学学院,河北石家庄050031 [3]河北省战略性关键矿产研究协同创新中心(河北地质大学),河北石家庄050031

出　　处：《现代地质》2025年第1期96-114,共19页Geoscience

基　　金：国家自然科学基金青年科学基金项目(42302086);国家自然科学基金重大研究计划项目(92162101);深时数字地球前沿科学中心项目(2652023001);高等学校学科创新引智计划项目(BP0719021)。

摘　　要：司家营矿床是冀东地区具有重要意义的BIF(条带状含铁建造)矿床,赋存于低变质作用的新太古代变质岩中。矿床的富铁矿成因仍存在一定争议。本文通过系统的岩相学、矿物学及矿物地球化学研究,详细探讨了司家营矿床的矿石特征,确认主要矿石类型为块状富磁铁矿与条带状贫磁铁矿。研究结果表明,该矿床内存在三种主要类型的磁铁矿:①原始沉积变质阶段的磁铁矿(Mt_(1)),以条带状分布,呈不规则粒状或似圆粒状,粒径相对较小,主要分布于低品位条带状磁铁矿中;②热液改造阶段的磁铁矿(Mt_(2)),呈不规则粒状,常与黄铁矿共生,内部偶见晶型发育较好的黄铁矿颗粒,主要存在于低品位条带状磁铁矿中;③铁质活化再富集阶段的磁铁矿(Mt_(3)),呈半自形至自形粒状,晶型发育良好,主要出现在高品位块状富磁铁矿中。Mt_(1)与Mt_(2)均属于条带状贫磁铁矿矿石中的磁铁矿,但Mt_(2)表现出明显的热液改造特征,Mt_(3)则是在早期形成的磁铁矿经历铁质活化再富集后形成的磁铁矿。研究认为,司家营矿床的富铁矿主要归因于BIF的铁质活化再富集作用。The Sijiaying banded iron formation(BIF)-hosted deposit,located in eastern Hebei Province,is a significant occurrence of iron ore within a suite of Neoarchean low-grade metamorphic rocks of amphibolite-greenschist facies.The metallogeny of the high-grade Fe mineralization at Sijiaying remains a subject of debate.This study presents a comprehensive investigation of the petrology,mineralogy,and geochemistry of ores from the Sijiaying BIF-hosted iron deposit to elucidate their genesis.The deposit predominantly comprises massive high-grade Fe ore and banded low-grade BIF.The ores are characterized by three distinct types of magnetite:First,magnetite from the original sedimentary-metamorphic stage(Mt_(1)),which exhibits a banded distribution and occurs as irregular or rounded granular forms,characterized by the smallest particle size found within the low-grade BIF.Second,magnetite from the hydrothermal alteration stage(Mt_(2)),which manifests as irregular granular configurations and frequently coexists with pyrite,occasionally containing well-developed pyrite grains,predominantly within the low-grade BIF.Third,magnetite from the iron remobilization and re-enrichment stage(Mt_(3)),which appears as subhedral to euhedral granules with well-formed crystal shapes,typically found in massive high-grade Fe ore.Both Mt_(1) and Mt_(2) are associated with the magnetite within the banded low-grade BIF,with Mt_(2) displaying clear characteristics of hydrothermal alteration.Conversely,Mt_(3) is indicative of magnetite originating from the massive high-grade Fe ore,resulting from remobilization and re-precipitation processes.It is concluded that the high-grade Fe mineralization of the Sijiaying deposit is primarily attributed to the remobilization and re-precipitation processes affecting the iron within the BIF.

关 键 词：磁铁矿 矿物地球化学 富铁矿 司家营铁矿 冀东 

分 类 号：P571[天文地球—矿物学] P575[天文地球—地质学] P611.3