叶蛇纹石和斜绿泥石的电导率、脱水动力学研究以及地球物理启示

Serpentine and chlorite are the very important hydrous minerals in the subduction zones, their dehydration behaviors are related to many geophysical observations, and therefore the dehydration mechanisms are very important to understanding the many physical and chemical properties of the Earth’s interior. However, dehydration effects on electrical conductivities of antigorite and clinochlore, the oxygen fugacity and magnetite effects on electrical conductivity of antigorite and clinochlore, and how the dehydration mechanism and the conduction mechanism tradeoff remain unclear. In this project we will study the electrical conductivity of before and after dehydration under different pressures and temperatures as well as different oxygen fugacity and different magnetite contents, compositions, microscopic character、dehydration behaviors, phase states, to obtain the dehydration mechanism, kinetics of dehydration equations and electrical conductivity. In addition, we plan to study the dehydration mechanism and the conduction mechanism to get the tradeoff between dehydration mechanism and conduction mechanism and build the new models between electrical conductivity and the carries. We will extrapolate the experimental results to the interior of subduction zones and compare with geophysical observations to provide the experimental base for the explanations of the MT observations.

蛇纹石和绿泥石是俯冲带中非常重要的两种含水矿物，对地球表面与地球内部的水循环发挥着非常重要的作用。蛇纹石和绿泥石的脱水效应与许多地球物理观测结果密切相关，蛇纹石和绿泥石的脱水机理对研究地球内部的许多物理化学性质具有重要的意义。然而，叶蛇纹石和斜绿泥石脱水后电导率如何变化、氧逸度和磁铁矿对他们的电导率有什么影响、以及脱水机制与导电机制如何耦合等问题并不清楚。本研究将在高温高压下研究叶蛇纹石和斜绿泥石不同脱水阶段电导率变化、不同氧逸度和磁铁矿条件下叶蛇纹石和斜绿泥石的电导率以及成分、脱水机理、相态，获得叶蛇纹石和斜绿泥石脱水机制和脱水动力学方程等信息。在此基础上，研究不同条件下叶蛇纹石和斜绿泥石的脱水机制和导电机制，探讨脱水机制与导电机制之间的耦合关系，并建立电导率与载流子之间的新模型。将实验室结果与大地电磁测深结果进行对比, 从而为大地电磁测深结果的解释提供一定的实验依据。

本研究通过对俯冲带典型含水矿物蛇纹石、绿泥石的脱水动力学、高温高压下电导率等方面的研究，获得了叶蛇纹石和斜绿泥石获脱水机制和脱水动力学方程等重要信息；以及不同脱水阶段电导率变化规律；获得了磁铁矿在蛇纹石脱水前后的变化规律。建立了蛇纹石和绿泥石的脱水模型和导电模型，发现了蛇纹石和绿泥石的在高温高压下脱水机制与导电机制直接的耦合关系。依据本研究所获得的实验结果，建立了不同俯冲带的电导率深度模型，对于大地电磁测深结果以及提供了重要约束。本研究所获得的结果对于研究俯冲带的水循环、火山活动的机理具有重要的意义。