摘要
通过对采自青藏高原的六种地壳岩石 ,包括花岗闪长岩、混合岩、片麻岩、玄武岩、辉橄岩及斜长角闪岩等 ,进行高温高压纵波速度测量 ,发现绝大多数地壳岩石其纵波速度在压力高于0 .2— 0 .3GPa时基本上随压力线性增加 .在固定压力下随温度升高而降低 ,但在温度较低时这一现象并不明显 ,随温度的升高波速出现明显降低 .通过对实验后的样品进行显微薄片分析 ,发现含水矿物的脱水和部分熔融是造成岩石波速迅速降低的主要原因 .在实验过程中还发现高压下温度较高时 ,接收到的超声波振幅会增大 .对实验中发现的这些现象本文进行了初步的分析和讨论 .
Compressional wave velocities ( V p ) in six crustal rocks collected from Tibet Plateau have been measured under high temperature and high pressure conditions. The experimental results show that V p of the most crustal rocks, increase linearly with pressure when the pressure is higher than 0.2-0.3 GPa, and slowly decrease with temperature until the temperature reach to a constant value then quickly decrease, but the values are not same for different samples. Examination of thin sections of the end products suggests that dehydrating and partial melting are possibly the main causes of rapid decrease of velocity. These data support the conclusion that dehydrating and partial melting are one of main causes of low velocity layer in Tibet Plateau crust. In addition, it is found that amplitudes of ultrasonic waves, which are transmitted through the samples, increase at high pressure and high temperature.
出处
《地球物理学进展》
CSCD
2002年第4期684-689,共6页
Progress in Geophysics
基金
国家自然科学基金项目 (10 0 32 0 4 0 )和 (4 9874 0 17)共同资助
关键词
地壳
岩石
弹性波速
纵波速度
脱水
部分熔融
低速层
温度
压力
High temperature and high pressure
Compressional wave velocity
Dehydrating
Partial melting
Low velocity layer
