气候变化领域集成服务门户(CCPortal): Immiscible metallic melts in the deep Earth: clues from moissanite (SiC) in volcanic rocks

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DOI	10.1016/j.scib.2020.05.012
	Immiscible metallic melts in the deep Earth: clues from moissanite (SiC) in volcanic rocks
	Huang J.-X.; Xiong Q.; Gain S.E.M.; Griffin W.L.; Murphy T.D.; Shiryaev A.A.; Li L.; Toledo V.; Tomshin M.D.; O'Reilly S.Y.
发表日期	2020
ISSN	20959273
起始页码	1479
结束页码	1488
卷号	65 期号:17
英文摘要	The occurrence of moissanite (SiC), as xenocrysts in mantle-derived basaltic and kimberlitic rocks sheds light on the interplay between carbon, hydrogen and oxygen in the lithospheric and sublithospheric mantle. SiC is stable only at ƒO2 < ΔIW−6, while the lithospheric mantle and related melts commonly are considered to be much more oxidized. SiC grains from both basaltic volcanoclastic rocks and kimberlites contain metallic inclusions whose shapes suggest they were entrapped as melts. The inclusions consist of Si0 + Fe3Si7 ± FeSi2Ti ± CaSi2Al2 ± FeSi2Al3 ± CaSi2, and some of the phases show euhedral shapes toward Si0. Crystallographically-oriented cavities are common in SiC, suggesting the former presence of volatile phase(s), and the volatiles extracted from crushed SiC grains contain H2 + CH4 ± CO2 ± CO. Our observations suggest that SiC crystalized from metallic melts (Si-Fe-Ti-C ± Al ± Ca), with dissolved H2 + CH4 ± CO2 ± CO derived from the sublithospheric mantle and concentrated around interfaces such as the lithosphere-asthenosphere and crust-mantle boundaries. When mafic/ultramafic magmas are continuously fluxed with H2 + CH4 they can be progressively reduced, to a point where silicide melts become immiscible, and crystallize phases such as SiC. The occurrence of SiC in explosive volcanic rocks from different tectonic settings indicates that the delivery of H2 + CH4 from depth may commonly accompany explosive volcanism and modify the redox condition of some lithospheric mantle volumes. The heterogeneity of redox states further influences geochemical reactions such as melting and geophysical properties such as seismic velocity and the viscosity of mantle rocks. © 2020 Science China Press
关键词	Alloy inclusion Mantle Moissanite Reduced gas
英文关键词	Aluminum compounds; Calcium compounds; Explosives; Iron compounds; Minerals; Nitrogen compounds; Phosphorus compounds; Redox reactions; Silicides; Silicon; Silicon carbide; Structural geology; Sulfur compounds; Titanium compounds; Uranium compounds; Volcanic rocks; Volcanoes; Explosive volcanism; Geochemical reaction; Geophysical properties; Lithospheric mantle; Metallic inclusions; Redox condition; Seismic velocities; Tectonic settings; Iodine compounds
语种	英语
来源期刊	Science Bulletin
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/207065
作者单位	ARC Centre of Excellence for Core to Crust Fluid Systems and GEMOC, Department of Earth and Planetary Sciences, Macquarie University, North Ryde, NSW 2109, Australia; State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan, 430074, China; Frumkin Institute of Physical Chemistry and Electrochemistry RAS, Moscow, 119071, Russian Federation; Key Laboratory of Gas Geochemistry, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China; Shefa Gems Ltd., Netanya, 42106, Israel; Diamond and Precious Metal Geology Institute, SB RAS, Yakutsk, 677007, Russian Federation; Center for Microscopy, Characterisation and Analysis, the University of Western Australia, Perth, 6009, Australia
推荐引用方式 GB/T 7714	Huang J.-X.,Xiong Q.,Gain S.E.M.,et al. Immiscible metallic melts in the deep Earth: clues from moissanite (SiC) in volcanic rocks[J],2020,65(17).
APA	Huang J.-X..,Xiong Q..,Gain S.E.M..,Griffin W.L..,Murphy T.D..,...&O'Reilly S.Y..(2020).Immiscible metallic melts in the deep Earth: clues from moissanite (SiC) in volcanic rocks.Science Bulletin,65(17).
MLA	Huang J.-X.,et al."Immiscible metallic melts in the deep Earth: clues from moissanite (SiC) in volcanic rocks".Science Bulletin 65.17(2020).