Discussion on ore forming conditions of supergene high grade hematite ores from Simandou deposit(Ⅰ and Ⅱ region)in Guinea
王永基 1李立兴 2姚顺义 3李朗田 1刘建权 4胡金才 4张旦 1夏斌1
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作者信息
1. 中国冶金地质总局中南局,湖北武汉 430081
2. 中国地质科学院矿产资源研究所自然资源部成矿作用与资源评价重点实验室,北京 100037
3. 武汉华泽科技发展有限公司,湖北武汉 430205
4. 天津华北地质勘查总院,天津 300170
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摘要
条带状铁建造(BIF—Banded Iron Formation)上部发育的赤铁矿床(w(TFe)＞62％)是全球最重要的铁矿资源,但对其成矿条件的认识仍然存在争议.文章以几内亚西芒杜赤铁矿矿床(Ⅰ、Ⅱ区块)为例,根据全球古板块(含BIF)漂移轨迹,并按成矿系统"五要素"(源、运、储、变、保)对全球风化淋滤型赤铁矿矿床的形成条件进行讨论.文章认为丰富的矿源层是形成赤铁矿床的基础;条带状铁建造出露地表,板块(含BIF)漂移穿过赤道和南、北回归线是必备条件;上亿年的热带环境和热带雨林生物及微生物的作用是脱硅的关键;富氧化铁矿石的后期改造提高矿石质量;赤铁矿矿体大部分得到保存能形成超大型矿床.
Abstract
Hematite deposits(w(TFe)＞62％)developed in the upper part of the banded iron formation(BIF)represent the most important iron ore resources in the world,but the ore-formation conditions remain debated.Taken the Si-mandou hematite deposit in Guinea as an example,and based on the drift trajectory of global ancient plates(con-taining BIF)and the"five elements"of mineralization system(including source,transport,storage,transforma-tion,and preservation),this paper discussed the ore-forming conditions of the BIF-hosted high-grade hematite de-posits in the world.We propose that abundant BIF layers are the basis for the formation of large-scale high-grade hematite deposits,the exposure of BIF layers to the surface and BIF-bearing plates drifting through the equator and Tropic of Cancer is a necessary condition,billions of years of tropical environment as well as tropical rainfor-est organisms and microorganisms is the key for desilicification,later alteration of hematite is favorable for in-creasing ore grade,and the preservation condition is also important for the formation of large-scale high-grade he-matite deposits.
关键词
条带状铁建造/风化淋滤/赤铁矿富矿/成矿条件/西芒杜
Key words
banded iron formation/supergene process/high-grade hematite ore/ore-forming condition/Simandou
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