Crustal melting and 3D analysis on melt migration in migmatites

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The size of leucosome varies from macroscopic to microscopic size. Rock-chip of 3x2.5x2 cm is cut to 16 slices in 1 mm interval by means of Leitz-rnicrotome. All figures are taken into Mac. Digital figures are treated on Photoshop and NIH Image. Three dimensional distribution and the form are observed using the animation of NIH Image. These treatments make clear the depletion of microscopic leucosome around the macroscopic leucosome.The degree of partial melting of pelitic gneisses and amphibolites has been estimated using average chemical compositions of cordierite tonalites and homblende tonalites on the assumption that these two types of tonalite magmas were originated from the partial melting of pelitic gneisses and amphibolites, respectively.We discussed the origin of the orbicular granite based on the spherical crystal growth of cordierite. Liquid unmixing between feldspathic melt and cordierite-apatite melt is most important factor. Highly enrichment of P and REE in orbicule is concordant with the unmixing model.