Abstract
High pressure-temperature experiments of olivine-methane were performed at 5.5 to 29.4GPa and 1200K to 2200K to examine stability of methane and formation of hydrocarbons. Diamond anvil cell combined with Nd-YAG laser and CO2 laser heating systems was used. XRD patterns showed that existence of olivine and their high pressure phases, solid methane were observed. Formation of ethane molecules was observed in the Raman spectroscopy. The Raman spectra of the recovered samples showed C-H vibration mode, assigned as long polymerized hydrocarbons. Graphite and glassy carbon were also observed. The results suggest that methane molecules partly dissociate, and dissociation proceeded to form pure carbon phases and hydrogen atoms in the Earth's mantle condition.
