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

我们研究了人造岩石和天然岩石在高压和高温条件下，造岩矿物之间的固相线下反应动力学。利用活塞筒式高压装置对高压合成的石榴石二辉橄榄岩进行了分析，得到了石榴石二辉橄榄岩矿物学中不同固相线下化学反应速度差异的实验结果。也就是说，钙-镁-铁的再分配，即简单的反应，在矿物中无处不在，而与铝有关的反应，如Tschermak取代，则在核心失败。这种现象可能是由于反应机制的相对复杂性，直接与不同地温之间的闭合温度不同有关。通过对天然岩石的结构和矿物化学的分析，结合实验研究，我们对天然岩石的结构和形成历史有了更深的理解。例如，我们可以破译霍罗曼橄榄岩曾经属于石榴石二辉橄榄岩相，尽管现在完全缺乏石榴石二辉橄榄岩相矿物学的痕迹。进一步研究：我们实验室的高压装置可以长时间保持压力。在这一点上，我们希望尽可能长时间地运行，以便进一步了解固相线下化学动力学。

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.