【摘要】 在200℃,0.95~7.70 GPa下,利用激光拉曼光谱技术研究了天然斜绿泥石晶体结构随压力的变化。在200℃,斜绿泥石481和786 cm-1谱峰随压力增加有规律地向高频方向偏移,拉曼位移(N,cm-1)与压力(P,GPa)的线性关系分别为:N=11.136P+482.6(R2=0.987 4)和N=5.055P+785.7(R2=0.983 7)。由于四面体层T阳离子与TOT层八面体M阳离子之间产生强烈的排斥作用,使Si—Onb键能增强,导致硅氧四面体层中Si—Onb键伸缩振动的865 cm-1谱峰随压力没有明显的频移。481和786 cm-1谱峰分别对应斜绿泥石晶体结构中M4八面体中M—Obr伸缩振动和Si—Obr—Si伸缩振动,频移说明M—Obr和Si—Obr键长缩短。在实验条件下绿泥石没有发生相变。研究结果说明,在某些冷俯冲带,绿泥石至少在80~90 km深部可能稳定存在,绿泥石脱水及其产生的流体可能是俯冲带地震孕育和发生的重要因素。更多还原

【Abstract】 Variation of crystal structure of natural clinochlore with pressure was investigated by the approach of diamond anvil cell(DAC) and in situ micro-Raman spectroscopic measurement at 200 ℃ and up to 7.7 GPa.The 481 and 786 cm-1 peaks shift towards high-frequency linearly with increasing pressure at 200 ℃.The linear relations between Raman shift(N,cm-1) and pressure(P,GPa) for the two peaks are: N=11.136P+482.6(R2=0.987 4) and N=5.055P+785.7(R2=0.983 7),respectively.The 865 cm-1 peak arising from the stretching mode of the Si—Onb shifts slightly because of the strong repulsion between T cations at the tetrahedral sites and M cations at the octahedral sites in the TOT layer.Raman shift of 481 cm-1 and 786 cm-1 means the shortening of the length of M—Obr and Si—Obr bonds since the peaks are contributed by the stretching mode of the M—Obr and Si—Obr,respectively.No phase transition of clinochlore under the experimental condition was found.The results indicate that chlorite minerals may be stable at least at a depth of 80-90 km in the cold subduction zones,and the fluid derived from chlorite dehydration may be an important fact for earthquake occurrence in the subduction zones.更多还原