高压下斜方和单斜辉石的超声波速度及其地球物理启示  

Ultrasonic velocities of orthopyroxene and clinopyroxene at high pressure and their geophysical implications

作　　者：张吉凯 王多君 蔡闹 刘庆 ZHANG JiKai;WANG DuoJun;CAI Nao;LIU Qing(College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院大学地球与行星科学学院,北京100049

出　　处：《地球物理学报》2024年第10期3828-3840,共13页Chinese Journal of Geophysics

基　　金：国家自然科学基金重大研究计划重点项目(91958216);国家自然科学基金(42374211);中央高校基本科研业务费资助。

摘　　要：辉石是主要的造岩矿物之一,在地幔岩模型中的含量仅次于橄榄石,占总体积的20%~30%.因此,高温高压下辉石的弹性,对于理解壳幔的物质组成、地震波不连续面的成因以及深部动力学过程具有重要的意义.本文以天然斜方辉石和单斜辉石为初始物,采用超声干涉法测量了两种样品在高压下的弹性波速.在实验的压力范围内,斜方辉石和单斜辉石的波速均随压力的升高而增大,二者速度值接近.依据本实验结果,结合其他地幔矿物的研究资料,采用Voigt-Reuss-Hill(VRH)方法计算了地幔橄榄岩在上地幔条件下的速度分布曲线.通过将计算结果与PREM模型对比,对地幔的物质成分进行了定量约束.Pyroxene is one of the main rock-forming minerals, and it is the second most abundant mineral in the pyrolite model after olivine. Therefore, the elasticity of pyroxene under high pressure and high temperature is of great significance for understanding the composition of crust-mantle materials, the causes of seismic discontinuities, and dynamic processes in the interior of the Earth. In this study, two natural pyroxenes, orthopyroxene and clinopyroxene, were hot-pressed to obtain polycrystalline aggregates, and their elastic wave velocities under high pressure was obtained through ultrasonic interferometry. Within the pressure range of this study, the wave velocities of orthopyroxene and clinopyroxene both increase with the pressure, but the values of wave velocities in this study are close. Combined the results of this study with previous results on other mantle minerals, velocity profiles of a pyrolite lithology were established using Voigt-Reuss-Hill (VRH) calculation. The calculated results were compared to the PREM model to constrain the composition of the mantle.

关 键 词：高压 斜方辉石 单斜辉石 超声波速 地幔岩模型 

分 类 号：P589[天文地球—岩石学] P313[天文地球—地质学]