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[SMP43-08] Correlations between the apparent interlayer spacings d002 and the Raman R2 parameters of carbonaceous matters in metamorphic rocks
Keywords:carbonaceous matter, d002, Raman R2
We have analyzed the Raman R2 parameters of CMs in rocks from the above three areas and compared them with the apparent d002 values reported in the above studies. Although standard deviations of the R2 parameters in individual rock specimens are large, the modal R2 parameters show good positive correlations with the apparent d002 values in the ranges R2 ≤ 0.75 and d002 < 3.60, while no clear correlation is shown out of the ranges (Fig. 1).
The correlation can be approximated by a simple hyperbolic equation, (R2 - a) (d002 - b) = k. Hence, we may estimate a metamorphic temperature in the above area from the previously reported apparent d002 value by combining the above two equations as T (ºC) = -445 (k / (d002 - b) + a) + 641. Asymptotic values for R2 (a) and d002 (b) and k for the all data in the above ranges are 0.95, 3.26 and -0.064, respectively, with R2 as 0.94. On the other hand, those only for the Asemi area are 0.96, 3.28 and -0.058, respectively, with R2 as 0.94, and for the Yasaka area are 0.89, 3.27 and -0.046, respectively, with R2 as 0.97, while those only for the Susa area can not be obtained, since the most data are out of the ranges.
Since the geothermometer of Beyssac et al. (2002) is applicable for the range, R2 < 0.7, the parameter set of the Asemi area obtained from the data mostly within the range is better to take for practical temperature estimations.