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现代地质 ›› 2025, Vol. 39 ›› Issue (01): 96-114.DOI: 10.19657/j.geoscience.1000-8527.2025.003

• 矿床学 • 上一篇    下一篇

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

张美诺1(), 石康兴2,3(), 邱昆峰1, 邓军1   

  1. 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
  • 出版日期:2025-02-10 发布日期:2025-02-20
  • 通信作者: 石康兴,男,博士,助理研究员,1994年出生,主要从事矿床学方面研究。Email: shikx1994@163.com
  • 作者简介:张美诺,女,硕士研究生,2000年出生,主要从事矿床学方面的研究。Email: zmn@email.cugb.edu.cn
  • 基金资助:
    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)

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

ZHANG Meinuo1(), SHI Kangxing2,3(), QIU Kunfeng1, DENG Jun1   

  1. 1. School of Earth Sciences and Resources,China University of Geosciences (Beijing), Beijing 100083, China
    2. College of Earth Sciences, Hebei GEO University, Shijiazhuang, Hebei 050031, China
    3. Hebei Province Collaborative Innovation Center for Strategic Critical Mineral Research (Hebei GEO University), Shijiazhuang, Hebei 050031, China
  • Published:2025-02-10 Online:2025-02-20

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(Mt1),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(Mt2),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(Mt3),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。Mt1与Mt2均属于条带状贫磁铁矿矿石中的磁铁矿,但Mt2表现出明显的热液改造特征,Mt3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。

关键词: 磁铁矿, 矿物地球化学, 富铁矿, 司家营铁矿, 冀东

Abstract:

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 (Mt1), 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 (Mt2), 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 (Mt3), which appears as subhedral to euhedral granules with well-formed crystal shapes, typically found in massive high-grade Fe ore. Both Mt1 and Mt2 are associated with the magnetite within the banded low-grade BIF, with Mt2 displaying clear characteristics of hydrothermal alteration. Conversely, Mt3 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.

Key words: magnetite, mineral geochemistry, high-grade iron mineralization, Sijiaying deposit, Eastern Hebei Province

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