辉绿岩脆-塑性变形转化的高温高压实验研究

以天然叶腊石为传压介质, 在温度800~100 0℃、围压0.6~1.0 GPa和应变速率10-4~10-5 s-1条件下, 对Maryland辉绿岩的脆性-塑性转化进行了实验研究.实验结果表明, 在10-4~10-5 s-1应变速率和固定围压1.0 GPa条件下, 当温度低于800℃时, 岩石变形为典型脆性破裂; 温度高于1000℃时岩石变形以准稳态蠕变为主; 温度在800~950℃之间, 岩石变形从脆性破裂向准塑性流动转化.温度变化对岩石脆-塑性转化影响敏感度高于压力变化对变形的敏感度.显微构造观察显示, 辉绿岩脆-塑性转化以稀疏弥漫状共轭塑性流动网络为特征. 

AN HIGH-TEMPERATURE AND HIGH-PRESSURE EXPERIMENTAL STUDY OF CHANGES BETWEEN BRITTLE AND DUCTILE DEFORMATIONS IN DIABASE

A series of experiments on the transfer between the brittle and ductile properties of the Maryland diabase was performed, with natural pyrophyllite as the medium for the pressure transfer, at the temperature ranging from 800 to 1 000 ℃, at the confining pressure ranging from 0.6 GPa to 1.0 GPa, and at the strain rate ranging from 10-4 to 10-5 s-1. The experiment results show that the rock is deformed into typical brittle fractures at the strain rate ranging from 10-4 to 10-5 s-1, at the confining pressure of 1.0 GPa, and at the temperature lower than 800 ℃. At the temperature higher than 1 000 ℃, the rock is deformed dominantly into the metastable creep. At the temperature ranging from 800 to 950 ℃, the deformation of the rock turns from the brittle fractures to the pseudo ductile flow. Therefore, the sensitive effect of the temperature change on the rock transfer between brittle and ductile properties is greater than that of the pressure change. The micro structural observation shows that the transfer between the brittle and ductile properties in the diabase is dominated by the conjugated ductile flow network in the form of the rarefaction and diffusion.