Abstract
Chondrules are quenched silicate droplets and characteristically included in condrites. In recent years, their 3-D structures have been examined by X-ray computed tomography (CT). It was proposed that voids are commonly present in chondrules although their amounts are small (up to 3 vol. %). This shows that voids are another important constituents of chondrules as well as silicates, Fe-Ni metal and Fe sulfides. In the present study, experimental reproduction of voids in chondrules was performed in a 1 atm furnace at constant temperature for different durations to examine the condition for void generation during chondrule formation. 3-D structures of the charges were obtained with X-ray CT. The charges were finally mounted in epoxy, sliced and polished, and observed under SEM to identify their phase and degree of partial melting and to compare CT images with SEM images. The porosities, connectivities, number density, 3-D shapes and size distribution of voids were obtained by image analysis, such as binarization of the 3-D CT images. Exponential and power distributions were observed at small and large degree of partial melting, respectively. Voids in natural chondrules have power distributions. 3-D shapes were not reproduced by present 1 atm experiments.
