Meeting room "Glova", 4 floor, Integrated Research Building
Abstract
The oxidation state of the mantle is known to be reduced with depth. In deeper part of the upper mantle, even H2-fluids exist in addition to H2O fluids. Previous studies clearly showed that olivine reacts with H2O to form hydrous olivine. Olivine is most abundant mineral in the mantle, thus olivine potentially important hydrogen reservoir in the Earth's mantle. As for H2 fluids, it is also of great interest whether hydrogen is incorporated into olivine structure. Here we show high pressure and temperature experiments using laser heated diamond anvil cells of H2-olivine reaction. X-ray diffraction patterns showed volume expansion of olivine, which suggested incorporating hydrogen into olivine structure. IR spectra of -OH stretching vibration mode was not observed, which indicated that hydrogen was not incorporated as hydroxyl like hydrous olivine. On the other hand, H2 vibron significantly softened than that of pure H2 was observed clearly by Raman spectroscopy. The present experimental results indicate that incorporation of hydrogen molecules into the olivine structure and that a certain intermolecular interaction was induced between hydrogen molecules and constituents of olivine. A new hydrogen incorporation mechanism different from hydrous olivine was proposed from the present study. Experiments of H2-wadsleyite system are also reported.
For inquiry：Taku Tsuchiya TEL:（089）927-8198
E-mail takut@sci.ehime-u.ac.jp
