Chemical Kinetics and texture interpretation of rocks at high pressures and temperatures

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We have made researches on chemical kinetics of subsolidus reactions among rock-forming minerals at high pressures and temperatures, of both synthetic and natural rocks. As natural rock samples, the Horoman peridotites and basic metamorphic xenoliths at Kibi Plateau were chosen.The most important outcome of the analysis of garnet lherzolites synthesized at high pressures using a piston-cylinder type high pressure apparatus is the experimental demonstration of differential velocities among various subsolidus chemical reactions in the garnet lherzolite mineralogy. That is, the Ca-Mg-Fe redistribuion ,that is rathe simple reaction, took place everywhere in the minerals while such an Al-related reaction as the Tschermak substitution failed at the core. This phenomena, probably due to the relative complexity of reaction mechanisms, would be directly related to the differential closure temperatures among various geothermometers.The analysis of texture and mineral chemistry of natural rocks , in conjunction with the experimental study, led us to deeper understandings in the textures and formation histories of natural rocks. For example, we could decipher that the Horoman peridotites once belonged to the garnet lherzolite facies though the peridotites now totally lack traces of garnet lherzolite facies mineralogy.Future studies : The high pressure apparatus in our laboratory can maintain pressure in lengthy period. On this benefit, we paln to make as lengthy runs as possible so that subsolidus chemical kinetics can be further understood.