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[1]张连昌,代堰锫,王长乐,等.鞍山—本溪地区前寒武纪条带状铁建造铁矿时代、物质来源与形成环境[J].地球科学与环境学报,2014,36(04):1-15.
　ZHANG Lian-chang,DAI Yan-pei,WANG Chang-le,et al.Age, Material Sources and Formation Setting of Procambrian BIFs Iron Deposits in Anshan-Benxi Area[J].Journal of Earth Sciences and Environment,2014,36(04):1-15.
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鞍山—本溪地区前寒武纪条带状铁建造铁矿时代、物质来源与形成环境(PDF)
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《地球科学与环境学报》[ISSN:1672-6561/CN:61-1423/P]

卷:
第36卷
期数:
2014年第04期
页码:
1-15
栏目:
基础地质与矿产地质
出版日期:
2014-12-15

文章信息/Info

Title:
Age, Material Sources and Formation Setting of Procambrian BIFs Iron Deposits in Anshan-Benxi Area
文章编号:
1672-6561(2014)04-0001-15
作者:
张连昌; 代堰锫; 王长乐; 刘利; 朱明田
中国科学院地质与地球物理研究所矿产资源研究重点实验室,北京 100029
Author(s):
ZHANG Lian-chang; DAI Yan-pei; WANG Chang-le; LIU Li; ZHU Ming-tian
Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
关键词:
条带状铁建造; 太古宙; 物质来源; 形成机制; 构造背景; 鞍山—本溪地区; 华北克拉通
Keywords:
banded iron formations;  Archean;  material source;  formation mechanism;  tectonic setting;  Anshan-Benxi area;  North China Craton
分类号:
P618.3
DOI:
-
文献标志码:
A
摘要:
前寒武纪条带状铁建造(BIFs)蕴含丰富的铁矿石资源，记录了早期地球演化的重要信息。鞍山—本溪地区发育巨量的太古宙BIFs。鞍山—本溪地区BIFs由互层的硅铁条带组成，金属矿物以磁铁矿为主，含少量赤铁矿、黄铁矿及菱铁矿等。围岩与BIFs呈整合接触，具有变火山岩的岩石学特征及地球化学特征，表明BIFs属于阿尔戈玛型，其变火山岩围岩年龄可大致代表BIFs沉积时代。锆石U-Pb年代学显示，鞍山—本溪地区至少发育约3.10Ga及约2.55Ga两期BIFs沉积成矿事件，后者在华北克拉通广泛发育.鞍山—本溪地区BIFs地球化学具有以下特征：①低的TiO2与Al2O3含量及高场强元素负异常，表明沉积过程中陆源碎屑物质加入量很少；②PAAS标准化REE配分模式显示重稀土元素富集，La、Y 及Eu正异常，暗示BIFs沉积自海水与海底高温热液的混合溶液；③接近同时代亏损地幔的εNd(t)值(3.0~4.7)，表明Fe可能来源于海底热液活动淋滤洋壳；④BIFs中仅发育少量黄铁矿，基本不显示Ce负异常且富集铁的重同位素(δ(57Fe)值为(0.13~2.73)×10-3)，暗示古海洋整体处于低硫、缺氧环境，BIFs的沉淀可能与富Fe2+溶液遭遇环境突变有关。元素地球化学分析表明，大孤山与陈台沟围岩具有弧火山岩特征，南芬与歪头山围岩类似于弧后盆地玄武岩，因此，鞍山—本溪地区BIFs沉积于火山弧相关构造背景。
Abstract:
Precambrian banded iron formations (BIFs) contain large amounts of iron ores and record some important in formation about the evolution of early earth.Anshan-Benxi area has huge occurrences of Archean BIFs, which are helpful to enrich the theories of BIFs metallogenesis and advance the understanding of early evolution of North China Craton.These hosting rocks all have parallel occurrences to BIFs, and they show petrological and geochemical affinities with meta-volcanics.Therefore, the BIFs belong to the Algoma type and their formation ages can be reflected by the ages of wall rocks.It is proposed that there are at least two-stage BIFs deposition at about 3.10 Ga and about 2.55 Ga in Anshan-Benxi area, and the latter is widely distributed in North China Craton.The geochemical features of these BIFs include:①low concentrations of Al2O3, TiO2 and high field strength elements, suggesting that terrigenous detrital materials contributed insignificantly to the chemical precipitation; ②enrichment in heavy rare earth elements with positive La, Eu and Y anomalies on PAAS-normalized REE patterns, indicating their precipitation from marine seawater with a high-temperature hydrothermal component; ③εNd(t) values (3.0-4.7) close to those of the coeval depleted mantle, implying that the iron is most likely derived from the leaching of oceanic crust by marine hydrothermal activities; ④BIFs have only a few pyrites within them, and most of them show no Ce anomaly with enrichment of δ(57Fe) ((0.13-2.73)×10-3), indicating that Archean ocean is in low abundances of S and O2. It is proposed that the deposition of BIFs is associated with environment variation during the transport of Fe2+-rich solutions. Geochemical analyses show that Dagushan and Chentaigou wall rocks have the characteristics of arcvolcanics, and Nanfen and Waitoushan rocks are similar to back-arc basin basalts. Therefore, the BIFs in Anshan-Benxi area are deposited in the volcanic arc setting.

参考文献/References:

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备注/Memo

备注/Memo:
收稿日期:2014-06-25
基金项目:国家重点基础研究发展计划(“九七三”计划)项目(2012CB416601);国家自然科学基金项目(41372100)
作者简介:张连昌(1959-),男,陕西西安人,研究员,博士研究生导师,理学博士,E-mail:lczhang@mail.igcas.ac.cn。
更新日期/Last Update: 2014-12-16