元素の拡散を用いた鉱物の冷却速度の推定

抄録

The method to estimate the cooling rate of meteorites on the basis of atomic diffusion in minerals is summarized. The best-fit cooling rate and burial depth are obtained by fitting a profile calculated by solving the diffusion equation to the observed chemical gradient and the width of lamellae measured by electron microprobe. The thickness of a eucntic crust of the HED parent body was estimated to be about 10 km from augite exsolution in pyroxene. A rapid cooling of a few hundreds °C/yr for pallasite was obtained on the basis of chemical zoning in olivine. Some problems with estimation of the cooling rate are also reviewed.