高温高压下水镁石在NaCl溶液中的脱水动力学研究

俯冲带含水矿物的脱水是一种重要的地质作用，含水矿物的脱水速率对于全面认识大洋俯冲带中源地震的成因机制具有非常重要的科学意义。已有的含水矿物脱水动力学研究主要集中于无水条件，因此含水条件下的流体组分和压力作用对含水矿物脱水速率的影响，以及具体的脱水机制等科学问题还尚不清楚。本课题拟开展高温高压下水镁石在NaCl溶液中的脱水动力学实验研究，以获得水镁石在不同浓度NaCl溶液中的脱水速率和脱水机制参数。在此基础上，建立恒温条件下，压力、NaCl浓度和脱水速率之间的理论模型，正确评价NaCl浓度和压力对脱水速率产生的影响。通过比较不同温度下这些影响作用的差异，有助于进一步理解地球深部环境中水镁石的脱水动力学行为。将水镁石在NaCl溶液中的脱水机制与前人的结果进行对比，有可能获得对水镁石脱水作用机理的全新认识。

The dehydration of hydrous mineral in subduction zones is an important geological process, and the dehydration rate of hydrous mineral is of great scientific significance to comprehensively understand the formation mechanism of intermediate-focus earthquakes in oceanic subduction zones. The published studies on the dehydration kinetics of hydrous minerals mainly concentrated in the anhydrous conditions, so some scientific problems including the effects of fluid component and pressure on the dehydration rates of hydrous minerals and the dehydration mechanism remain unclear. We attempt to carry out an in-situ dehydration kinetics study of brucite in NaCl solution under high pressure and high temperature, thus obtaining the dehydration rate and dehydration mechanism of brucite in different concentrations of NaCl solution. Based on these kinetics parameters, we will establish the theoretical model among the pressure, the NaCl concentration and the dehydration rate under constant temperature condition, and that the effects of NaCl concentration and pressure will be properly evaluated. By comparing the differences of these effects at various temperatures, it will contribute to further understand the dehydration kinetics behavior of brucite existed within the deep environment of the Earth. We will compare the dehydration mechanism of brucite in NaCl solution with the results achieved in previous studies and a new understanding on the dehydration mechanism of brucite may be obtained.