globalchange  > 气候变化与战略
DOI: 10.1016/j.scib.2020.05.012
论文题名:
Immiscible metallic melts in the deep Earth: clues from moissanite (SiC) in volcanic rocks
作者: 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.
刊名: Science Bulletin
ISSN: 20959273
出版年: 2020
卷: 65, 期:17
起始页码: 1479
结束页码: 1488
语种: 英语
中文关键词: 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
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
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/169921
Appears in Collections:气候变化与战略

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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

Recommended Citation:
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]. Science Bulletin,2020-01-01,65(17)
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