Host: The Mineralogical Society of Japan
Introduction Plagioclase is one of the major minerals in the earth crust. Information of its melt and glass provide a cru for understanding properties of magma. In this study, the structures of plagioclase glasses densified by static compression were investigated by Raman spectroscopy and X-ray diffraction measurement.Experimental Plagioclase glasses with composition of Ab100, Ab50An50, and An100 were densified under the conditions of 4.0GPa-500C, 7.7GPa-500C and 7.7GPa-20C by a cubic anvil press. The densities of these glasses were measured by heavy liquid technique. Raman spectra and X-ray diffraction intensities are also measured.Results and Discussions By compression at 500C, densities increased with increasing pressure. The density increase increases with An content. The pressure variation of Raman spectra and FSDP (First Sharp Diffraction Peak) position of X-ray diffraction profiles may indicate that the density increase of plagioclase glass is due to the decrease of T-O-T angle, increase of 3-membered rings of TO4 tetrahedra, and increase of 6-fold Al. Large density increase of An100 glass may suggest that increase of 6-fold Al largely contribute density increase of plagioclase glass.
