高温高压条件下蛇纹岩电导率的测定结果及其在地震研究中的意义
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摘要
通过高温高压实验测量蛇纹岩在不同温压条件下的电导率，压力从200MPa到1100MPa，温度从100℃到1100℃。实验表明，在1GPa压力范围内，蛇纹石大约在650～700℃范围发生脱水反应。蛇纹石脱水导致电导率升高。其机理是自由水的出现可使岩石周围物质溶解，使得其中离子数量增加，因此会使电导率增大。蛇纹石作为一种重要含水矿物在俯冲带究竟可以被带到地球内部哪个深度，将取决于蛇纹石脱水反应的P－T条件和俯冲带的热结构。水的出现可以使周围岩石在较低温度下，提前出现部分熔融乃至熔融。因此，蛇纹石脱水发生的深度范围能够很好的解释岛弧岩浆的成因及火山热管的来源。并可能是地幔水的重要来源。蛇纹石水解所产生的体积和能量的变化还可能是深层地震发生的重要原因之一。
The conductivity of serpentine has been experimentally measured at pressure of 200 MPato 1100 MPa and temperature of 100℃ to 1100℃. The results show that within the pressurerange of 1 GPa, the dehydration occurs at 650℃ to 700℃ for serpentine and dehydrationcauses the increase of conductivity. The mechanism of the conductivity increase is the free water associated with dissolution of surrounding materials. Serpentine is one of the important water-bearing minerals. What depth can it be brought to during subducting of plate? It dependson the P-T conditions of its dehydration and the thermal structure of subduction belt. The emergency of free water can also lead to the occurrence of partial melting or melting at lowertemperature. This may explain the genesis of island-arc-magma and the source of volcanicthermotube. The changes of volume and energy during dehydration of serpentine may be oneof the important causes for deep seismicity.
The conductivity of serpentine has been experimentally measured at pressure of 200 MPato 1100 MPa and temperature of 100℃ to 1100℃. The results show that within the pressurerange of 1 GPa, the dehydration occurs at 650℃ to 700℃ for serpentine and dehydrationcauses the increase of conductivity. The mechanism of the conductivity increase is the free water associated with dissolution of surrounding materials. Serpentine is one of the important water-bearing minerals. What depth can it be brought to during subducting of plate? It dependson the P-T conditions of its dehydration and the thermal structure of subduction belt. The emergency of free water can also lead to the occurrence of partial melting or melting at lowertemperature. This may explain the genesis of island-arc-magma and the source of volcanicthermotube. The changes of volume and energy during dehydration of serpentine may be oneof the important causes for deep seismicity.
引文
1 高平,刘若新,马宝林.绿泥石片岩和斜长角闪岩在高温高压下的物理力学性质及其应用.地震地质,1994,16(1):83～88.
2 高平,郭才华,张友南.高温高压下岩石相变及物理性质综合研究实验系统.见:中国矿物岩石地球学学会,地幔矿物岩石地球化学专业委员会编.上地幔特征与动力学论文集.北京:地震出版社,1990.170～177.
3 1961. 50～90.
2 高平,郭才华,张友南.高温高压下岩石相变及物理性质综合研究实验系统.见:中国矿物岩石地球学学会,地幔矿物岩石地球化学专业委员会编.上地幔特征与动力学论文集.北京:地震出版社,1990.170～177.
3 1961. 50～90.
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