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

我们研究了合成岩石和天然岩石在高压和高温下形成岩石的矿物之间的亚固体反应的化学动力学。选取基比高原霍罗曼橄榄岩和基性变质包体作为天然岩石样品。用活塞缸式高压装置对高压合成的石榴石沸石进行分析，最重要的结果是实验证明了石榴石沸石矿物学中各种亚固体化学反应的速度差。即Ca-Mg-Fe再分配是一种相当简单的反应，在矿物中到处发生，而与al相关的Tschermak取代反应在岩心失败。这种现象，可能是由于反应机制的相对复杂性，将直接关系到不同的地温计关闭温度的差异。天然岩石的结构和矿物化学分析，结合实验研究，使我们对天然岩石的结构和形成历史有了更深入的认识。例如，我们可以破译出霍罗曼橄榄岩曾经属于石榴石-辉橄榄岩相，尽管现在的橄榄岩完全缺乏石榴石-辉橄榄岩相矿物学的痕迹。未来研究方向：本实验室高压装置可长时间保持压力。基于这一点，我们打算尽可能地进行长时间的试验，以便进一步了解固体化学动力学。

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.