Moissanite (SiC) with metal-silicide and silicon inclusions from tuff of Israel: Raman spectroscopy and electron microscope studies

Larissa Dobrzhinetskaya*, Pavel Mukhin, Qin Wang, Richard Wirth, Earl O'Bannon, Wenxia Zhao, Lev Eppelbaum, Tatiana Sokhonchuk

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Here, we present studies of natural SiC that occurs in situ in tuff related to the Miocene alkaline basalt formation deposited in northern part of Israel. Raman spectroscopy, SEM and FIB-assisted TEM studies revealed that SiC is primarily hexagonal polytypes 4H-SiC and 6H-SiC, and that the 4H-SiC polytype is the predominant phase. Both SiC polytypes contain crystalline inclusions of silicon (Sio) and inclusions of metal-silicide with varying compositions (e.g. Si58V25Ti12Cr3Fe2, Si41Fe24Ti20Ni7V5Zr3, and Si43Fe40Ni17). The silicides crystal structure parameters match Si2TiV5 (Pm-3m space group, cubic), FeSi2Ti (Pbam space group, orthorhombic), and FeSi2 (Cmca space group, orthorhombic) respectively. We hypothesize that SiC was formed in a local ultra-reduced environment at respectively shallow depths (60–100 km), through a reaction of SiO2 with highly reducing fluids (H2O–CH4–H2–C2H6) arisen from the mantle “hot spot” and passing through alkaline basalt magma reservoir. SiO2 interacting with the fluids may originate from the walls of the crustal rocks surrounding this magmatic reservoir. This process led to the formation of SiC and accompanied by the reducing of metal-oxides to native metals, alloys, and silicides. The latter were trapped by SiC during its growth. Hence, interplate “hot spot” alkali basalt volcanism can now be included as a geological environment where SiC, silicon, and silicides can be found.

Original languageEnglish
Pages (from-to)355-368
Number of pages14
JournalLithos
Volume310-311
DOIs
StatePublished - Jun 2018

Funding

FundersFunder number
National Science FoundationEAR-1620423, NSF EAR-1620423
National Natural Science Foundation of China41273039

    Keywords

    • 4H-SiC
    • 6H-SiC
    • Metal-silicides
    • Moissanite
    • Silicon
    • Tuff-tuffite

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