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现代地质 ›› 2024, Vol. 38 ›› Issue (01): 46-55.DOI: 10.19657/j.geoscience.1000-8527.2023.122

• 中国东部富铁矿成矿机制与找矿预测 • 上一篇    下一篇

冀北招兵沟铁磷矿床成矿时代及成因研究

王亿1(), 李立兴1(), 李厚民1, 李小赛1, 马兰晶2, 邢玉亮2, 孙欣宇3, 戴阳3, 王小慧1   

  1. 1.自然资源部成矿作用与资源评价重点实验室,中国地质科学院矿产资源研究所,北京 100037
    2.河北省地质矿产勘查开发局第五地质大队,河北 唐山 063002
    3.中国地质大学(北京)地球科学与资源学院,北京 100083
  • 收稿日期:2023-06-10 修回日期:2023-11-11 出版日期:2024-02-10 发布日期:2024-03-20
  • 通讯作者: 李立兴,男,博士,研究员,1984年出生,矿床学专业,主要从事金属矿床成因与成矿规律研究。Email:llixing@cags.ac.cn
  • 作者简介:王 亿,男,硕士研究生,1997年出生,矿床学专业,主要从事金属矿床成因与成矿规律研究。Email:cagswangyi@163.com
  • 基金资助:
    国家重点研发计划项目(2022YFC2903701);国家自然科学基金项目(42072112);中国地质调查局地质调查项目(DD20221684);中国地质调查局地质调查项目(DD20221695)

Geochronology and Genesis of the Zhaobinggou Fe-P Deposit, Northern Hebei, China

WANG Yi1(), LI Lixing1(), LI Houmin1, LI Xiaosai1, MA Lanjing2, XING Yuliang2, SUN Xinyu3, DAI Yang3, WANG Xiaohui1   

  1. 1. MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China
    2. The Fifth Geological Brigade of Hebei Provincial Bureau of Geology and Mineral Resources Exploration and Development, Tangshan, Hebei 063002, China
    3. School of Earth Sciences and Resources, China University of Geosciences (Beijing), Beijing 100083, China
  • Received:2023-06-10 Revised:2023-11-11 Online:2024-02-10 Published:2024-03-20

摘要:

为探讨冀北—辽西地区太古宙变质岩系中铁磷矿床的成因问题,本研究选取招兵沟矿床开展了岩相学、年代学和地球化学研究。野外观察表明,前人描述的条带状铁磷矿石实际上大多为含铁磷矿脉的黑云角闪斜长片麻岩,可见铁磷矿脉切穿片麻理。含铁磷黑云角闪斜长片麻岩中的锆石与矿石矿物铁钛氧化物和磷灰石密切共生。阴极发光图像上显示基性岩浆锆石特征,无/弱环带或斑块状结构,LA-ICP-MS U-Pb定年获得206Pb/238U加权平均年龄为(282±3)Ma(MSWD=0.78),指示铁磷矿化时代为早二叠世,而非传统认为的新太古代。招兵沟含铁磷黑云角闪斜长片麻岩与区域辉石-角闪石岩侵入体形成时代接近,微量元素地球化学特征相似度高,说明成矿母岩为辉石-角闪石岩。招兵沟铁磷成矿与冀北地区沿红石砬—大庙断裂带发育的显生宙阿拉斯加型镁铁-超镁铁质岩浆活动密切相关。综合来看,招兵沟铁磷矿床可能是与基性岩浆活动有关的矿床,而非传统认为的变质型矿床,其他相似矿床的成因也需要进一步研究。

关键词: 铁磷矿床, 成矿年龄, 矿床成因, 阿拉斯加型岩体, 华北克拉通

Abstract:

In order to investigate the genesis of the iron-phosphorus (Fe-P) deposits hosted in the Archean metamorphic series in Northern Hebei-Western Liaoning, we carried out petrographic, geochronological, and geochemical studies on the typical Zhaobinggou deposit.Field observations show that the so-called “the banded Fe-P ore” is hosted as veins in the biotite-hornblende-plagioclase gneiss, and is characterized by the gneissic schistosity with cross-cutting Fe-P veins.The formation of the vein folds is associated with the post tectonic deformation.Zircons in the Fe-P-bearing biotite-hornblende-plagioclase gneiss are intergrown with the Fe-Ti oxides and apatite.Cathodoluminescence imaging of these zircon grains shows no or weak zoning or patchy texture, which is typical of mafic magmatic origin.Zircon U-Pb dating using LA-ICP-MS technique obtained a weighted average age at (282±3) Ma (MSWD=0.78), which constrains the Fe-P mineralization to be in the early Permian, rather than Neoarchean as supposed previously.Comprehensive comparison studies show that the geochemical characteristics and the ore-forming age of the Zhaobinggou Fe-P-bearing biotite-hornblende-plagioclase gneiss are similar to those of the regional mafic pyroxenite-hornblendite, which is considered as the parent rock of the Fe-P mineralization.The results indicate that the Zhaobinggou Fe-P deposit is associated with Phanerozoic Alaskan-type mafic-ultramafic magmatism along the Hongshila-Damiao fault zone, but not related to any metamorphism as reported previously.Further investigations are needed for revealing the genesis of other similar deposits.

Key words: Fe-P deposit, ore-forming age, ore genesis, Alaskan-type complex, North China Craton

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