Progressive Low-Grade Metamorphism Reconstructed from the Raman Spectroscopy of Carbonaceous Material and an EBSD Analysis of Quartz in the Sanbagawa Metamorphic Event, Central Japan

Low-grade metamorphic temperature conditions associated with the Sanbagawa event were estimated by Raman spectroscopy of carbonaceous material (RSCM) in pelitic rocks and an electron backscatter diffraction (EBSD) analysis quartz siliceous rocks. Analytical samples collected from complex, Mikabu greenstones, Chichibu accretionary complex eastern Kanto Mountains, central Japan. Previously, low-grade metamorphism was only broadly recognized as pumpellyite–actinolite facies assigned to chlorite zone. The RSCM results indicate temperatures 358 °C 368 for zone 387 garnet 315 234–266 complex. From EBSD analyses, diameter grains calculated root mean square (RMS) approximation ranges 55.9 69.0 μm 9.5 23.5 2.9 7.3 opening angles c-axis fabric approximate 40–50°, presenting 324–393 greenstones. show a continuous increase no apparent gaps these metamorphosed In addition, there exists empirical exponential relationship between RMS values grains. this study, integrated analyses multiple rock types provided valuable information on progressive similar approach may be applied study other complexes.