高温高压下斜长岩纵波速度与电导率实验研究  

THE EXPERIMENTAL STUDIES ON ELECTRICAL CONDUCTIVITIES AND P-WAVE VELOCITIES OF ANORTHOSITE AT HIGH PRESSURE AND HIGH TEMPERATURE

作　　者：白利平[1] 杜建国[1] 刘巍[1] 周文戈[2] 

机构地区：[1]中国地震局分析预报中心,中国北京100036 [2]中国科学院地球化学研究所,中国贵阳550002

出　　处：《地震学报》2002年第6期638-646,共9页Acta Seismologica Sinica

基　　金：国家自然科学基金(10032040; 49874013); 地震科学联合基金(101119)资助项目.

摘　　要：在1.0 Pa、室温到880℃分别采用超声波透射法和阻抗谱法测量了斜长岩的纵波速度和电导率,并对实验产物进行了鉴定分析.结果表明,在680℃,由于斜长岩中的含水矿物绢云母和黝帘石发生脱水反应,岩石的纵波速度开始大幅度下降.在410℃～750℃、12～105 Hz的频率范围内,斜长岩只出现颗粒内部传导.由于脱水产生的自由水主要分布于矿物的三联点或颗粒拐角处,没有形成连通的高导性网络,因此,脱水作用不会导致斜长岩电导率显著增加,也不会改变其电传导机制.地球内部低速层和高导层的形成与演化可能具有非同步性,通过含水矿物脱水可以形成地球内部的低速层,但不一定同时形成高导层.Results of P-wave velocity (vP) and electrical conductivity measurements on anorthosite are presented from room temperature to 880C at 1.0 GPa using ultrasonic transmission technique and impedance spectra technique respectively. The experiments show that the P-wave velocities in anorthosite decrease markedly above 680C following the dehydration of hydrous minerals in the rock, and the complex impedances collected from 12 Hz to 105 Hz only indicate the grain interior conduction mechanism at 1.0 GPa, from 410C to 750C. Because the fluids in the rock have not formed an interconnected network, the dehydration will not pronouncedly enhance the electrical conductivity and change the electrical conduction mechanism. It is concluded that the formation and evolution of the low-velocity zones and high-conductivity layers in the crust may have no correlations, and the dehydration can result in the formation of the low-velocity zones, but cannot simultaneously result in the high-conductivity layers.

关 键 词：斜长岩 纵波速度 电导率 阻抗谱法 脱水作用 含水矿物 超声波透射法 

分 类 号：P57[天文地球—矿物学]