气候变化领域集成服务门户(CCPortal): Greenalite and its role in the genesis of early Precambrian iron formations

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DOI	10.1016/j.earscirev.2021.103613
	Greenalite and its role in the genesis of early Precambrian iron formations – A review
	Rasmussen B.; Muhling J.R.; Krapež B.
发表日期	2021
ISSN	0012-8386
卷号	217
英文摘要	Iron formations are marine sedimentary rocks comprising Fe-rich and Si-rich bands that were most widely deposited before ~2.45 Ga, prior to the Great Oxidation Event (GOE). They host most of the world's iron resources but their scientific importance lies in their potential for tracking the evolution of ancient seawater chemistry. Most models of their deposition (see reviews by Bekker et al., 2010, 2014; Konhauser et al., 2017) assume that iron oxides in iron formations were derived from original Fe(III)-oxides/hydroxides that were precipitated in the photic zone from Fe(II)-rich seawater via biologically mediated oxidation, the Fe(II) ultimately being derived from hydrothermal vent plumes. In this review, we present an alternative model for the origin of iron formations centred on petrographic observations that indicate that the depositional (original) iron phase was an Fe(II)-silicate (greenalite) that precipitated in vent plumes as nanometer-sized particles and silt-sized flocs. The greenalite was deposited throughout the oceans and, in times of increased mafic-ultramafic volcanism, on continental shelves. Paragenetic studies indicate that the bulk of the iron oxides in iron formations formed by replacement of Fe(II)-rich precursors during metamorphism, deformation and exhumation. The origin of early Precambrian iron formations by precipitation of greenalite from vent plumes implies that iron deposition was largely an abiotic chemical process that did not require biologically driven oxidation, consistent with the lack of microfossils and indigenous organic matter. © 2021 Elsevier B.V.
英文关键词	Early earth; Greenalite; Hydrothermal systems; Iron formation; Iron oxides; Precambrian Ocean chemistry
语种	英语
scopus关键词	continental shelf; early Earth; formation mechanism; host rock; hydrothermal system; hydrothermal vent; iron; iron oxide; marine sediment; metallogenesis; microfossil; mineral resource; ore deposit; paleoceanography; Precambrian
来源期刊	EARTH-SCIENCE REVIEWS
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/209315
作者单位	School of Earth Sciences, The University of Western Australia, Perth, Western Australia 6009, Australia
推荐引用方式 GB/T 7714	Rasmussen B.,Muhling J.R.,Krapež B.. Greenalite and its role in the genesis of early Precambrian iron formations – A review[J],2021,217.
APA	Rasmussen B.,Muhling J.R.,&Krapež B..(2021).Greenalite and its role in the genesis of early Precambrian iron formations – A review.EARTH-SCIENCE REVIEWS,217.
MLA	Rasmussen B.,et al."Greenalite and its role in the genesis of early Precambrian iron formations – A review".EARTH-SCIENCE REVIEWS 217(2021).