高温高压下斜长角闪岩的Vp:熔体含量和形态的综合影响  

COMPRESSIONAL WAVE VELOCITIES FOR AMPHIBOLITE AT HIGHTEMPERATURE AND PRESSURE:COMBINED EFFECTS OF MELTING VOLUME PERCENTAGES AND MORPHOLOGICAL FEATURE

作　　者：安邦[1,2] 蒋玺[1] 黄扬[1,2] 

机构地区：[1]贵州大学资源与环境工程学院,贵州贵阳550003 [2]贵州大学研究生院,贵州贵阳550025

出　　处：《矿物岩石》2012年第1期21-27,共7页Mineralogy and Petrology

基　　金：国家自然科学基金(40804019);贵州省科学技术基金(黔科合J字[2008]2251号);贵州大学引进人才科研项目([2007]006号)

摘　　要：在YJ3000t高压装置上,利用超声波脉冲透射-反射法测量恒压0.6GPa,1.0GPa和2.0GPa,室温至1 195℃条件下斜长角闪岩的纵波波速(Vp),统计了实验中间产物中各组分的体积百分含量和熔体形态(二面角),并根据主要矿物含量和弹性参数,利用VRH平均模型计算了高温高压下斜长角闪岩的Vp。结果显示,不同压力下,样品的Vp随温度升高首先缓慢降低,在温度达约850℃～950℃时转而快速下降。实验产物观测显示,随温度升高熔体含量显著增加,二面角不断减小,熔体由封闭囊状演变为连通薄膜,部分熔融是导致岩石Vp快速降低的主要因素。高温高压下Vp计算结果与测量结果有相同的Vp-T变化趋势,其对比研究表明,岩石初始熔融时,熔体尚未连通,此时熔体含量控制着岩石Vp的降低。部分熔融加剧导致熔体逐渐连通,此时不同压力下熔体导致Vp下降有差异,这可能与熔体连通过程中熔体薄膜的形态因子变化有关。Measurements on compressional wave velocities （Vp） for amphibolite were carried out with the unltrasonic wave transmission-reflection method by YJ3000t multi-anvil apparatus at the temperature up to 1 100 ℃ and at the pressure of 0. 6 GPa,1.0 GPa and 2.0 GPa respectively. The volume percentages and dihedral-angle of melt mass were investigated in the run products. With the percentages of minerals and their elastic parameters, the temperature and pressure varia- tion of Vp for amphibolite were calculated by using Voigt-Reuss-Hill （VRH） model. The results indicate that at first the Vp of specimen decreases slowly with increasing temperature, then de- creases quickly about 850℃ to 950 ℃ under different pressure. Investigations on the products show that with the rise of temperature, the volume percentages of melt mass increase obviously and the dihedral-angle decrease constantly, and the melt mass develops from closed pockets into connected film. Partial melting of specimen is responsible for the decrease of Vp with increasing temperature. The calculation shows a same Vp-T correlations with experiment run at high tem- perature and pressure,and the comparison demonstrates that Vp is controlled by the volume per- centages of melt mass at the beginning of dehydration and partial melting, while the melts mass are not connected each other. The growth of partial melting leads to the gradual connection of the melt mass. The melt has different affects on Vp under different pressures which may be related to the different ＂a＂ of melt mass.

关 键 词：高温高压 斜长角闪岩 部分熔融 二面角 纵波波速 

分 类 号：P589.1[天文地球—岩石学]