Crystallization of spherical (Mg,Fe)-oxides in the shocked Martian meteorite Northwest Africa 7755

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Marco E. Ciriotti
Messaggi: 25339
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
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Crystallization of spherical (Mg,Fe)-oxides in the shocked Martian meteorite Northwest Africa 7755

Messaggio da Marco E. Ciriotti » gio 10 gen, 2019 15:13

Referenza:
▪ Zhang, A.C., Wang, S.Z., Tomioka, N., Lu, X.C., Ding, Z.Y., Ma, C., Wang, P., Chen, J.N., Xu, S., Gu, L.X., Bai, Y.Q., Li, Y., Sakamoto, N., Wang, R.C, (2019): Crystallization of spherical (Mg,Fe)-oxides by particle attachment in the shocked Martian meteorite Northwest Africa 7755. American Mineralogist, 104, (in press).
Marco E. Ciriotti

«Things are interesting only in so far as they relate themselves to other things»

Avatar utente
Marco E. Ciriotti
Messaggi: 25339
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
Contatta:

Re: Crystallization of spherical (Mg,Fe)-oxides in the shocked Martian meteorite Northwest Africa 7755

Messaggio da Marco E. Ciriotti » gio 31 gen, 2019 11:39

Referenza:
▪ Zhang, A.C., Wang, S.Z., Tomioka, N., Lu, X.C., Ding, Z.Y., Ma, C., Wang, P., Chen, J.N., Xu, S., Gu, L.X., Bai, Y.Q., Li, Y., Sakamoto, N., Wang, R.C, (2019): Crystallization of spherical (Mg,Fe)-oxides by particle attachment in the shocked Martian meteorite Northwest Africa 7755. American Mineralogist, 104, 150-157.

Abstract:
Crystallization is one of the most fundamental processes for both solid inorganic and organic materials in nature. The classical crystallization model mainly involves the monomer-by-monomer addition of simple chemical species. Recently, nanoparticle attachment has been realized as an important mechanism of crystallization in comparatively low-temperature aqueous natural and synthetic systems. However, no evidence of crystallization by particle attachment has been reported in petrologically important melts. In this study, we described spherical (Mg,Fe)-oxides with a protrusion surface in a shock-induced melt pocket from the martian meteorite Northwest Africa 7755. Transmission electron microscopic observations demonstrate that the (Mg,Fe)-oxides are structure-coherent intergrowth of ferropericlase and magnesioferrite. The magnesioferrite is mainly present adjacent to the interface between (Mg,Fe)-oxides spherules and surrounding silicate glass, but not in direct contact with the silicate glass. Thermodynamic and kinetic considerations suggest that development of the spherical (Mg,Fe)-oxides can be best interpreted with crystallization by particle attachment and subsequent Ostwald ripening. This indicates that crystallization by particle attachment can also take place in high-temperature melts and has potential implications for understanding the nucleation and growth of early-stage crystals in high-temperature melts, such as chondrules in the solar nebula, erupted volcanic melts, and probably even intrusive magmas.
Marco E. Ciriotti

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