date: 2012 October 17 (Wed) 15:00-16:00
room: CPS Conference Room
speaker: Hitoshi Miura (Tohoku University)
organizer: Hiroshi Kimura
title: Theoretical approach to understand formation process of chondrule solidification textures
abstract: Chondrules are millimeter-sized and spherical-shaped crystalline grains consisting mainly of silicate material. They are considered to have formed from molten droplets about 4.6 billion years ago in the solar nebula; it is believed that they melted and cooled again to get solidification in a short period of time. They must have great information about the early history of our solar system. Their solidification condition has been investigated experimentally for the last few decades. On the other hand, the experimental results have not been interpreted on the basis of the theory of crystal growth. We are numerically modeling the solidification process based on a phase-field model, which is one of the powerful models to numerically solve the first-order phase transformations. We apply this model to the silicate system to investigate the fundamental processes on chondrule melt solidification: change in the crystal shape, recalescence, elemental partitioning, and elemental diffusion. We would like to talk about reconsideration of chondrule formation condition based on the numerical results.
keywords: Chondrule, Solidification, Recalescence, Elemental partitioning, Morphological instability