古地理学报 ›› 2020, Vol. 22 ›› Issue (5): 965-976. doi: 10.7605/gdlxb.2020.05.065

• 古地理学及矿产资源专辑 • 上一篇    下一篇

华北克拉通南缘石炭系本溪组铁-铝黏土矿物质来源: 以河南三门峡大安铝黏土矿床为例*

刘学飞1, 王庆飞1, 马遥1, 李中明2, 赵利华1, 周智慧1, 刘百顺2, 马欣莉1   

  1. 1中国地质大学(北京)地球科学与资源学院,北京 100083;
    2河南省地质调查院,河南郑州 450001
  • 收稿日期:2020-06-21 修回日期:2020-08-19 出版日期:2020-10-01 发布日期:2020-10-14
  • 作者简介:刘学飞,男,1983年生,中国地质大学(北京)副教授、博士生导师,主要从事表生过程与成矿作用相关研究。E-mail: lxf@cugb.edu.cn
  • 基金资助:
    *国家自然科学基金项目(编号: 41972073,41672089)和教育部高校基本科研业务费项目(编号: 2652019065)联合资助

Provenance of iron, bauxite and clay deposits of the Carboniferous Benxi Formation in southern margin of North China Craton: An example from Da'an bauxite and clay deposit of Sanmenxia area,Henan Province

Liu Xue-Fei1, Wang Qing-Fei1, Ma Yao1, Li Zhong-Ming2, Zhao Li-Hua1, Zhou Zhi-Hui1, Liu Bai-Shun2, Ma Xin-Li1   

  1. 1 School of Earth Science and Resources,China University of Geosciences(Beijing),Beijing 100083,China;
    2 Geological Survey Institute of Henan Province,Zhengzhou 450001,China
  • Received:2020-06-21 Revised:2020-08-19 Online:2020-10-01 Published:2020-10-14
  • About author:Liu Xue-Fei,born in 1983,is an associate professor and doctoral supervisor of China University of Geosciences(Beijing). He is mainly engaged in the study of supergene process and mineralization. E-mail: lxf@cugb.edu.cn.
  • Supported by:
    Co-funded by the National Natural Science Foundation of China(Nos. 41972073,41672089)and the Basic Research Funds of the Ministry of Education(No. 2652019065)

摘要: 华北克拉通在中奥陶世至晚石炭世期间一直出露地表,经历了长期的风化作用,形成大规模的铁-铝黏土矿,其成矿物源一直是研究的热点,尤其是本溪组底部铁矿和铁质黏土矿与上部铝黏土矿是否为同一来源尚未查清。本研究选取克拉通南缘大安铝黏土矿床作为研究对象,展开微区矿物及元素地球化学组成分析,进一步探讨铁-铝黏土矿物质来源。大安矿床内含矿岩系自下而上包括铁质黏土岩、铝土矿、铝质黏土矿;局部喀斯特高地缺失铝土矿,铝质黏土矿直接覆盖于铁质黏土岩之上。铁质黏土岩在洼地以菱铁矿、黄铁矿和伊利石为主,在隆起区以赤铁矿、伊利石和高岭石为主。铝土矿以硬水铝石、伊利石和锐钛矿为主;铝质黏土矿主要矿物为伊利石。矿物微区分析在黏土矿底部发现大量的碳化硅和少量自然硅、硅铁矿、铬铁矿;区域对比揭示北秦岭造山带内商丹缝合带和二郎坪群中的蛇绿岩为铝黏土矿形成提供了成矿物质。本溪组底部铁质黏土与上部铝黏土矿稳定元素比率(例如Zr/TiO2Hf/TiO2Nb/TiO2Ta/TiO2)存在明显差异,揭示二者为不同来源: 底部铁质黏土岩和铁矿层为底板碳酸盐岩原地风化的产物;而上部铝黏土矿是异地搬运物,北秦岭造山带在晚石炭世的整体抬升为华北铝黏土矿形成提供了重要的成矿物质。

关键词: 华北克拉通, 铝黏土矿, 矿物微区分析, 碳化硅, 稳定元素, 物质来源

Abstract: During the Middle Ordovician to Late Carboniferous period,the North China Craton(NCC)was exposed and experienced prolonged weathering that resulted in the formation of large-scale iron,clay and bauxite deposits. The source of ore-forming material has always been a research focus,in particular,whether the sources of the iron ore and the Fe-bearing clay at the bottom of Benxi Formation are the same as the upper bauxite and clay deposit is still unclear. In this study,the Da'an bauxite and clay deposit at the southern margin of the NCC was chosen to carry out a detailed analysis of the micro-region mineral composition and elemental geochemical characteristics for further exploring the sources of iron,bauxite and clay deposits. The composition of the ore-bearing rocks in the Da'an bauxite deposit from the bottom to top includes Fe-bearing clay(locally iron ore),bauxite,and bauxitic clay;locally,in karstic uplift,bauxitic clay layer is directly overlying on the Fe-bearing clay. The Fe-bearing clay is dominated by siderite,pyrite,and illite in the karstic depression,and hematite,illite,and kaolinite in the uplift. Bauxite is mainly composed of diaspore,illite,and anatase,while bauxitic clay is mainly composed of illite. Mineral microanalysis revealed the development of large amounts of moissanite and small amounts of natural silica,silicalite,and chromite at the bottom of bauxitic clay layer. Regional comparison and correlation reveal that the ophiolite in the Shangdan suture zone and Erlangping Group in the North Qinling orogenic belt(NQOB)likely provides source materials for bauxite and clay deposits. The obvious differences in immobile element ratios (e.g., Zr/TiO2,Hf/TiO2,Nb/TiO2,Ta/TiO2)between the bottom Fe-bearing clay layer and the upper bauxite and clay layer in Da'an deposit,revealing that they are from different sources. The bottom Fe-bearing clay and iron ore layers are the products of in-situ weathering of underlying carbonates,while the top bauxite and clay are allochthonous. The regional uplift of the NQOB during the Late Carboniferous period provided important ore-forming materials for the formation of the NCC bauxite and clay deposits.

Key words: North China Craton, bauxite and clay deposit, mineral microanalysis, moissanite, immobile elements, provenance

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