|Budget Amount *help
¥11,100,000 (Direct Cost: ¥11,100,000)
Fiscal Year 1988: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1987: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1986: ¥9,800,000 (Direct Cost: ¥9,800,000)
A new guide block system to generate ultrahigh pressure and temperature was designed and constructed in this research, and experiments on phase transition and melting of silicate systems relevant to geophysics were conducted by using this high pressure system. The present guide block system combined with the multiple anvil (MA8) and uniaxial press could successfully generate up to 25 GPa and 2400゜C. By using this system, we could synthesize Mg-perovskite MgSiO_3, which is the most important candidate of the lower mantle.
The phase change work on the system MgSiO_3-FeSiO_3-Al_2O_3 has conducted at 1800゜C and up to a pressure of 25 GPa. Tetragonal garnet is stable in the MgSiO_3-FeSiO_3 system in the pressurte range from 16 GPa to 23.5 GPa and the compositions from pure MgSiO_3 to about 45mol% of FeSiO_3. The trtragonal garnet-perovskite transition occurs at 23.5 GPa and 1800゜C.
Partitioning behaviors of some trace elements between majorite garnet and the ultrabsic melt were also studied by using the present high pressure system. The trace elements studied were refractory lithophile elements (Al, Ca, Ti, Sc, V, La. Sm, Gd, Yb, Zr, and Hf), four siderophile elements (Fe, Ni, Mn, and Cr) and two volatile elements (Na and K). The concentrations of these elements were measured by using EPMA and SIMS (Secondary ion mass spectrometry). The measurement using SIMS was conducted by collaboration with University of Tsukuba.
The present experiments summarized above proves that the present high pressure and temperature system constructed by this research has remarkable capability to generate ultrahigh pressure and temperature and to conduct experiments for geophysical interests.