气候变化领域集成服务门户(CCPortal): Early continental crust generated by reworking of basalts variably silicified by seawater

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DOI	10.1038/s41561-019-0408-5
	Early continental crust generated by reworking of basalts variably silicified by seawater
	André L.; Abraham K.; Hofmann A.; Monin L.; Kleinhanns I.C.; Foley S.
发表日期	2019
ISSN	17520894
卷号	12 期号:9
英文摘要	The Archaean continental crust comprises two major groups of silicon-rich granitoids: the tonalite–trondhjemite–granodiorite and granite–monzonite–syenite suites, which differ in their sodium-to-potassium ratios. How these felsic granitoids evolved from their mafic precursors remains elusive and the subject of great debate. Here, we present silicon isotopic constraints on the formation of representative trondhjemitic and granitic plutons from the Kaapvaal craton that range in age from 3.51–2.69 billion years ago. We identified very consistent silicon isotopic signatures, all uniformly 0.1–0.2‰ heavier than rocks of the modern continental crust. This unusual composition is explained by the melting of a mafic source that included significant proportions (15–35 wt%) of silicified basalts, which were common supracrustal rocks before 3 billion years ago. Before the melting event that formed the granitoid magmas at depth, portions of the mafic source rocks were enriched in silica by interaction with silica-saturated seawater. The addition of silica depresses the stability of amphibole at similar water activity, allowing trondhjemitic and granitic melt production at lower temperatures from protoliths with contrasting silica contents: 52–57 and ≥60 wt%, respectively. This explains why granitoids were able to form very early in Earth history but did not emerge in significant amounts on other rocky planets. © 2019, The Author(s), under exclusive licence to Springer Nature Limited.
语种	英语
scopus关键词	amphibole; Archean; basalt; continental crust; granite; granitoid; isotopic analysis; melting; monzonite; pluton; potassium; silica; sodium
来源期刊	Nature Geoscience
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/124606
作者单位	Earth Science Department, Royal Museum for Central Africa, Tervuren, Belgium; Laboratoire G-Time, Département Géosciences, Environnement et Société, Université Libre de Bruxelles, Brussels, Belgium; Tritium Science Group, United Kingdom Atomic Energy Authority, Abingdon, United Kingdom; Department of Geology, University of Johannesburg, Johannesburg, South Africa; FB Geowissenschaften—Isotopengeochemie, Universität Tübingen, Tübingen, Germany; Department of Earth and Planetary Sciences, Macquarie University, Sydney, NSW, Australia
推荐引用方式 GB/T 7714	André L.,Abraham K.,Hofmann A.,et al. Early continental crust generated by reworking of basalts variably silicified by seawater[J],2019,12(9).
APA	André L.,Abraham K.,Hofmann A.,Monin L.,Kleinhanns I.C.,&Foley S..(2019).Early continental crust generated by reworking of basalts variably silicified by seawater.Nature Geoscience,12(9).
MLA	André L.,et al."Early continental crust generated by reworking of basalts variably silicified by seawater".Nature Geoscience 12.9(2019).