【摘要】 报道了100～300℃、0.5～4.0GPa条件下辉长岩纵波速度(vP)和横波速度(vS),并且根据品质因子(QP、QS)的变化讨论了该条件下辉长岩的物性特征及其地震地质意义。实验结果表明:压力为0.5～4.0GPa时,固定温度下辉长岩vP、vS、QP、QS随压力增大而递增,并且在0.5～2.3GPa压力范围内它们随压力的变化率比在2.3～4.0GPa范围内的大;固定压力下,温度从100℃增至300℃时,辉长岩vP、vS、QP、QS呈线性下降趋势。进一步分析得到:在0.5～2.3GPa压力下,随着压力的增加辉长岩样品不断被压缩,样品的连续性变好,弹性加强,弹性波衰减变小,波速与Q值升高;在2.3～4.0GPa压力下,样品被压密,样品接近连续弹性介质,弹性波衰减很小,波速与Q值的变化速率变小;在温度为100～300℃条件下,辉长岩样品内部以膨胀为主,样品密度变小,弹性波速与Q值呈线性下降趋势。研究结果表明,在岩石圈内构造应力局部集中会导致岩石Q值增大,岩石破裂、热物质局部聚集会导致岩石Q值降低,这也解释了地震前后观测到的震源区Q值的类似变化。更多还原

【Abstract】 The variations of the elastic properties of gabbro at 100～300℃ and 0.5～4.0GPa and the seismogeological application of the experimental results are discussed based on the measured wave velocities(vP,vS)and quality factors(QP,QS)of the gabbro.The values of vP,vS,QP and QS increase in the pressure range from 0.5 to 4.0GPa at the given temperatures,but decrease slightly when the temperature increase from 100 to 300℃ at the given pressures.The variations of velocities and quality factors may be mainly attributed to the compression of the gabbro sample,and the continuity and elasticity of the sample become better at 0.5～2.3GPa.The gabbro sample almost becomes continuous elastic medium at 2.3～4.0GPa,resulting in smaller change of elastic wave velocities and attenuation.The wave velocities and quality factors decrease with increasing temperature because of thermal expansion and density decrease of gabbro.The experimental results can be used to explain the observed geophysical phenomena that the quality factor are enhanced by stress aggregation in the lithosphere,the quality factors may be reduced by rock fracturation and local enrichment of hot fluids in the epicentral areas before and after earthquake occurrence.更多还原