S1: Earth materials science in igneous processes (Special Session)

[S1-03] Estimating timescales of chemical diffusion in melts utilizing a holocrystalline composite dike

「発表賞エントリー」

*Ayu Yamazaki¹, Tetsuo Kawakami¹, Fumiko Higashino² (1. Kyoto Uni. Sci., 2. Okayama Uni. Science)

Keywords:chemical diffusion, timescale, holocrystalline rock, composite dike, magma mixing

MgO in Bt and CaO in Pl showed assymmetric chemical profiles at the boundary between felsic and intermediate rocks in a holocrystalline composite dike. They were almost flat in the intermediate rock whereas in the felsic rock they showed decreasing diffusion profile (R²>0.8) from the boundary between the intermediate rock. Almost the same diffusion distances for Ca and Mg were observed in the felsic rock side. These observation indicate that the chemical diffusion took place in a melt and preserved as a mineral composition. Timescale of diffusion in the melt was estimated as <10⁴ years.