Theoretical study on crystallization process from chondrule melt using phase-field method

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Chondrules are millimeter-sized, once-molten, spherical-shaped grains mainly composed of silicate material. They are considered to have formed from chondrule precursor particles that were heated and melted through flash heating events in the solar nebula and cooled again to solidify in a short period of time. To elucidate the formation process of their solidification textures, we carried out numerical simulations of solidification of olivine based on the phase-field method. The formation of barred-olivine texture can be explained by the morphological instability of solid-liquid interface during the rapid cooling. It was found that a cooling rate required to reproduce the typical width of olivine bars is about two orders of magnitude larger than that suggested previously. We also showed that the linear chemical zoning observed in overgrowth layer of olivine phenocryst have formed by such rapid cooling.