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.
Key words：High pressure and high temperature;Clinochlore;Raman spectroscopy;Earthquake
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