与前寒武纪含铁建造有关的铁矿床基本特征及研究进展

Characteristics and research progress of iron deposits related to Precambrian iron-bearing formation

与前寒武纪含铁建造有关的铁矿床是最具经济价值的铁矿床类型,多形成于太古代和早元古代海底的环境。含铁建造结构多呈条带状,故被认为条带状含铁建造(BIF),粒状含铁建造(GIF)较为少见。条带状含铁建造是由各种富铁矿物组成的非均一组合,矿物包括含铁的氧化物、硅酸盐、碳酸盐和硫酸盐。而粒状含铁建造则主要由含铁的氧化物和硅酸盐组成,偶而富含含铁碳酸盐。根据结构及组成的不同,含铁建造可分为两类:阿尔戈马型(Algoma type)和苏必利尔型(Superior type),其中苏必利尔型含铁建造是最为重要的成矿母岩。以其为母岩形成的矿床可分为三类:未经富集的原生含铁建造矿床,假象赤铁矿-针铁矿矿床和高品位赤铁矿矿床,其中以高品位赤铁矿矿床最为重要,其形成与成岩作用、表生作用及深部流体的参与有关。我国在下一步工作中应加强对中高品位矿床成因的研究,并对国内已有类似矿床进行再认识,进而取得找矿突破。

The iron deposits related to Precambrian iron-bearing formation,formed in the environment of Archean and early Proterozoic sea floors,are the most economical iron deposit types in the word.Most of the structures of iron-bearing formation show a banding distribution and are named as banded iron-bearing formation（BIF）,which is a non-uniform combination composing of various iron-rich minerals and mineral compoents are mainly of iron-bearing oxide,silicate,carbonate and sulfate.The uncommon granular iron-bearing formation（GIF） are mainly composed of iron-bearing oxide and silicate,while iron-bearing carbonate are rare.According to different structures and compositions,the iron-bearing formation can be divided into two categories： Algoma type and Superior type,and the Superior type iron-bearing formation is the most important host-rock for iron deposit.The iron deposits hosted by superior type iron-bearing formation can be further divided into three types： primary iron-rich iron-bearing formation,hematite-goethite deposits with false appearance and high-grade hematite deposit.In addition,the high-grade hematite ore is the most important deposit which is associated with diagenesis,supergene and deep fluids.In order to obtain prospecting breakthrough,we should strengthen research on genetic study of high-grade mineral deposits in the future work and reconsider the deposits that have a similar geological background.