高温高压下电导-温度曲线方法进行蛇纹石的脱水温度测量及其意义

DEHYDRATION TEMPERATURE OF SERPENTINE AT ELEVATED TEMPERATURES AND PRESSURES BY ELECTRICAL CONDUCTIVITY METHOD AND ITS IMPLICATIONS

在1．0～5．0GPa压力范围内，运用高温同时高压下电导测量方法确定了蛇纹石的脱水温度。实验结果表明，压力小于2.0GPa时叶蛇纹石的脱水温度随压力的增大呈微弱升高趋势，压力大于2．0GPa时其脱水温度随压力的增大明显降低，意味着较高压力下有利于脱水反应的发生，是俯冲带岩浆作用及地幔交代作用流体的重要来源。蛇纹石脱水后，由于自由水的存在导致其电导明显增加，可能是高导层产生的原因之一。

Dehydration temperatures of serpentine were measured in the pressure range between 1. 0 GPa and 5. 0 GPa hy using the electrical conductivity method simutaneously at high tempera-tures and high pressures. The results show that with increasing pressure the dehydration tempera-ture of antigorite increases slightly below 2. 0 GPa, but drops markedly above 2. 0 GPa. This strongly suggests that high pressure would favor the dehydration of serpentine minerals and the water released thereby would be an important source of fluids involved in magmatism in a subduc-tion zone and mantle metasomatism. Meanwhile, the greatly enhanced electric conductivity in the presence of water may be one of the reasons underlying the occurrence of a high-conductivity zone in the lower crust.