| Autor: |
Zhang, Ai-Cheng, Wang, Shu-Zhou, Tomioka, Naotaka, Lu, Xian-Cai, Ding, Zhi-Yuan, Ma, Chi, Wang, Peng, Chen, Jia-Ni, Xu, Sheng, Gu, Li-Xin, Bai, Yuan-Qiang, Li, Yang, Sakamoto, Naoya, Wang, Ru-Cheng |
| Předmět: |
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| Zdroj: |
American Mineralogist; Jan2019, Vol. 104 Issue 1, p150-157, 8p |
| Abstrakt: |
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. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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