高温高压下斜长角闪岩弹性、电学性质及其地质意义  

The Elastic and Electrical Properties for Amphibolite at High Temperature and High Pressure and Their Geological Implication

作　　者：万方[1,2] 周文戈[1] 刘永刚[1] 范大伟[1,2] 谢鸿森[1] 

机构地区：[1]中国科学院地球化学研究所地球深部物质与流体作用地球化学实验室,贵阳550002 [2]中国科学院研究生院,北京100049

出　　处：《地质科技情报》2008年第6期47-52,共6页Geological Science and Technology Information

基　　金：中国科学院知识创新工程重要方向项目(KJCX2-SW-N20);西部之光联合学者项目;国家重点基础研究发展计划项目(2005CB724400)

摘　　要：在1.0 GPa、室温至700℃条件下,分别采用超声波反射-投射法和阻抗谱法,测量了华北克拉通北缘绿泥石化斜长角闪岩的弹性波纵波速度和电导率。在常温、压力〉0.35 GPa的条件下,斜长角闪岩的弹性波纵波速度与压力呈线性关系,说明此时岩石中的微裂隙已经基本闭合。依据该线性关系,得到常温常压下斜长角闪岩的弹性波纵波速度为6.390 7 km/s,压力系数为0.160 6 km/（s.GPa）。在1.0 GPa条件下,斜长角闪岩的弹性波纵波速度与温度呈线性关系,温度系数为-0.000 594km/（s.℃）。在1.0 GPa、200-700℃条件下,斜长角闪岩样品的电导率符合Arrhenius公式,指前因子为25.78-105.32 S/m,活化能为0.57-0.66 eV。利用实验获得的弹性波纵波速度及其温度系数和压力系数以及电导率与温度的关系,结合现今华北克拉通地热学的基本参数,计算得到斜长角闪岩的弹性波纵波速度-深度剖面和电导率-深度剖面,将二者分别与华北克拉通北缘深部地壳的弹性及电性结构进行对比的结果表明：高温高压下绿泥石化斜长角闪岩的弹性波纵波速度与该地区中地壳速度相当,电导率介于中、下地壳范围内。综合来看,实验的绿泥石化斜长角闪岩有可能是组成现今华北克拉通北缘的中地壳岩石之一。The P-wave velocity （vp） and electrical conductivity of chloritic amphibolite are measured at 1.0 GPa, from room temperature to 700℃, using ultrasonic reflection-transmission combined method and impedance spectra method respectively. The sample comes from northern margin of the North China craton. At room temperature, when the pressure exceeding 0.35 GPa, the % of amphibolites has a linear relationship with pressure, which indicates the tiny gaps in the rock sample had been closed. Based on this relationship, the vp of the amphibolite obtained is 6. 390 7 km/s, and the pressure coefficient is 0. 160 6 km/ （s · GPa）. At 1.0 GPa, the vp of amphibolites has a linear relationship with the temperature, the temperature coefficient is --0. 000 594 km/（s ·℃）. The conductivity of amphibolite can be fit to Arrhenius equation at 1.0 GPa and 200--700℃, the pre-exponential factor is 25.78--105.32 S/m and the activation energy is 0.57--0.66 eV. The P-wave velocity-depth profile and electrical conductivity-depth profile can be calculated from the experimental data and the fundamental geothermal parameters in northern margin of the North China craton. The comparison of the calculated results with the elastic and electrical structure of this area reveals that the vp of amphibolite is approximately equal to the middle crust, the electrical conductivity of amphibolite intersects the range of the middle and lower crust in this area. With together, the chloritic amphibolites may be a kind of rocks making up the middle crust in northern margin of the North China craton.

关 键 词：纵波速度 电导率 地壳结构 高温高压 斜长角闪岩 

分 类 号：P588.12[天文地球—岩石学] P589[天文地球—地质学]