喀麦隆西南部Mamelles条带状铁建造元素地球化学特征

Geochemical characteristics of the Mamelles banded iron formations in Southwest Cameroon

SOH TAMEHE Landry ¹GANNO Sylvestre ²陈祖兴 ³ROSIèRE Carlos Alberto⁴

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作者信息

1. 中国有色桂林矿产地质研究院有限公司,广西桂林 541004
2. Department of Earth Sciences,University of Yaounde Ⅰ,812 Yaounde,Cameroon
3. 中国科学院海洋研究所,山东青岛 266071
4. Department of Geology,Universidade Federal de Minas Gerais,31270-901 Belo Horizonte,Minas Gerais,Brazil
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摘要

Mamelles铁矿床位于喀麦隆南部刚果克拉通西北缘,距离克里比地区东南方向约20 km.该矿床由大规模、高品位磁铁矿矿体组成,赋存于Nyong杂岩体的条带状铁建造(BIF)中.该矿床中的BIF与角闪岩和片麻岩相伴生.在详细的野外调查基础上,我们获取了BIF的全岩地球化学数据,并用以约束它们的物质来源和沉积环境.弱正铕(Eu)异常(δEu=2.14～3.55)表明高温热液流体对Mamelles BIF的贡献是通过海底火山岩蚀变作用的方式,并有少量碎屑物质输入.正铈(Ce)异常的缺失表明,这些BIF可能沉积在缺氧的深海环境中,如火山弧或弧后盆地深水区.

Abstract

The Mamelles iron ore deposit is located approximately 20 km southeast of the Kribi area at the north-western edge of the Congo Craton in southern Cameroon.The deposit comprises massive high-grade magnetite orebodies hosted by banded iron formations(BIFs)of the Nyong Complex.The BIFs in this deposit are associated with amphibolites and gneisses.Within the framework of detailed field investigation,we report whole-rock geo-chemical data of the BIFs to constrain their sources and depositional settings.Weak positive Eu anomalies(6Eu=2.14-3.55)indicate the contribution of high-temperature hydrothermal fluids to the Mamelles BIFs derived via submarine alteration of volcanics,with slightly detrital input.The absence of true Ce anomalies indicates that the BIFs were likely deposited in anoxic deep seawater.Deposition of the Mamelles BIF sequence occurred in volcanic arc or back-arc settings.

关键词

刚果克拉通/喀麦隆/Mamelles铁矿/条带状铁建造/地球化学

Key words

Congo Craton/Cameroon/Mamelles iron deposit/BIF/geochemistry

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基金项目

山东省自然科学基金青年基金(ZR2020QD069)

出版年

2024

海洋科学

中国科学院海洋研究所

海洋科学

CSTPCDCSCD北大核心

影响因子：0.541

ISSN：1000-3096

参考文献量38

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