BIFs的形成及其铁氧化机制研究进展与展望  

Formation and iron oxidation mechanisms of BIFs:Research progress review and outlook

作　　者：黄柳琴 李林鑫 蒋宏忱 HUANG Liuqin;LI Linxin;JIANG Hongchen(State Key Laboratory of Biogeology and Environmental Geology,China University of Geosciences(Wuhan),Wuhan 430074,China)

机构地区：[1]中国地质大学(武汉)生物地质与环境地质国家重点实验室,湖北武汉430074

出　　处：《地学前缘》2023年第2期333-346,共14页Earth Science Frontiers

基　　金：国家自然科学基金项目(42172340,91951205)。

摘　　要：条带状铁建造(banded iron formations, BIFs)是早前寒武纪(3.8~1.8 Ga)缺氧古海洋中大规模Fe(Ⅱ)氧化形成的一类富铁沉积岩,具有典型的硅质层与铁质层互层的条带状或层状结构,形成的铁矿物主要以磁铁矿和赤铁矿为主。BIFs构成了全球规模最大、储量最多的铁矿类型,具有重大的经济价值。BIFs也是地球环境与生命协同演化的产物,是研究早期地球许多重大演化事件(如大氧化事件)独特的载体。然而,由于早前寒武古海洋环境和沉积条件的独特性,尽管经过了近百年的研究,BIFs成因仍存在许多未解之谜。其中,最关键的科学问题莫过于溶解态Fe(Ⅱ)如何在缺氧古海洋中大量氧化形成特定的铁矿物组合。本文首先概述了BIFs类型、物质组成及来源,以及沉积条件等基本信息;然后从BIFs特殊的沉积环境入手,综述了前人提出的Fe(Ⅱ)氧化机理及存在的一些问题,讨论了微生物驱动下的氮元素生物地球化学循环对Fe(Ⅱ)氧化及BIFs形成的贡献及相关研究进展,最后对BIFs成因研究提出了展望。Banded-iron formations(BIFs), typically consisted of interbanded iron-and silica-rich layers, are unique iron-rich sediments precipitated by extensive Fe(II) oxidation in the anoxic-hypoxic ocean during the Early Precambrian Era(mainly 3.8-1.8 Ga). The most abundant iron-containing minerals in BIFs are magnetite and hematite. BIFs provide the largest iron source to form giant iron ores that are of great economic value. Furthermore, as BIFs are closely related to the two billion-year co-evolution of life and earth environments, they are unique geological records for studying the important evolutionary events(e.g., the rise of atmospheric O_(2)) on the early Earth. However, few modern BIF analogues have been discovered due to the uniqueness of the Early Precambrian paleomarine environment and sedimentary conditions. Thus, there are still many unsolved mysteries about the origin of BIFs, despite intensive research in the past century. Among them, the most critical scientific question is how the dissolved Fe(Ⅱ) was oxidized to form specific mineral assemblages in the anoxic paleo-ocean. In this review, the basic information on BIF types, material compositions and sources, as well as sedimentary conditions are summarized, followed by the proposed mechanisms of Fe(Ⅱ) oxidation and their inherent problems from the perspective of special sedimentary environment of BIFs. Also discussed are the contribution of microbial-mediated nitrogen biogeochemical cycle to Fe(Ⅱ) oxidation and the formation of BIFs and related research progress. Lastly, an outlook on the genetic study of BIFs is discussed.

关 键 词：条带状铁建造 生物成因 铁氧化机制 氮循环耦合的铁氧化过程 

分 类 号：P534.2[天文地球—古生物学与地层学] P534.3[天文地球—地质学] P597