Reaction process of metamorphic minerals.

In this research project，following three studies concerning with reacation processes of metamorphic minerals were carriedout.(1)构造hydrothermal equipment：A hydrothermal equipment was specia-ly designed and constracted to carry out experiments up to 9001 kb.(2) Determination of diffusion constant of silica in supercritical water：The most important factor of reaction kinetics in metamorphism and metasomatism is a diffusionconstant of silica in supercritcal water. The diffusion constants measured using Thehydrothermal equipment constructed in (1). The experiments done on The system；sio_2 - Mg(oh_2), sio_2 - MgO, sio_2 - Ca(oh_2), sio_2 - CaO，sio_2 - cac_3 . The amounts of reaction products were incleased linearly with The root of durationtime. Based on this relationship， the diffusion constant是calculated as follows；d = do.exp ([- (e + mv ^ *)] / rt), do = 0.55 (+ 0.57, -0.28) cm ^ 2 / sec, e = 48 (< plus-minus > 5) neil / mol .,V^*= 81<plus-minus>12) cm^3/mol., where R and T are gas constant and temperature，(3) Appearence of high-temperature form of cordierite in metamorphic rock：Cordierite is major phase of metamorphic rocks and has two polymorphs，high- and low-temperature forms. While no reports were there on occurrence of the high-temperatureforms in metamorphic rock，sector trilling of cordierite transformed from the high-temperature form was found in the present研究。Furthermore, based on appearence of the sector trilling，the contact metamorphic rock can be classfied into two zones with cordierite. Stability field of thehigh-temperature form was also studied using the hydrothermal equipment of (1). the stability field这是最广泛的那些reviously reported and the high-form is stable even at 700 C。

In this research project, the following three studies concerning with reacation processes of metamorphic minerals were carried out.(1) Construction of hydrothermal equipment: A hydrothermal equipment was specia-ly designed and constracted to carry out experiments up to 900゜C and 1 kb.(2) Determination of diffusion constant of silica in supercritical water: The most important factor of reaction kinetics in metamorphism and metasomatism is a diffusion constant of silica in supercritcal water. The diffusion constants was measured using the hydrothermal equipment constructed in (1). The experiments were done on the system; SiO_2 - Mg(OH)_2, SiO_2 - MgO, SiO_2 - Ca(OH)_2, SiO_2 - CaO, SiO_2 - CaCO_3. The amounts of reaction products were incleased linearly with the root of duration time. Based on this relationship, the diffusion constant were calculated as follows; D = Do.exp([-(E+PV^*)]/RT), Do = 0.55(+0.57, -0.28) cm^2/sec, E = 48(<plus-minus>5) kj/mol., V^*= 81<plus-minus>12) cm^3/mol., where R and T are gas constant and temperature, respectively.(3) Appearence of high-temperature form of cordierite in metamorphic rock: Cordierite is major phase of metamorphic rocks and has two polymorphs, high- and low-temperature forms. While no reports were there on occurrence of the high-temperature forms in metamorphic rock, sector trilling of cordierite transformed from the high-temperature form was found in the present study. Furthermore, based on appearence of the sector trilling, the contact metamorphic rock can be classfied into two zones with cordierite. Stability field of the high-temperature form was also studied using the hydrothermal equipment of (1). The stability field is wider than those reviously reported and the high-form is stable even at 700゜C.