[SSS17-P18] Raman spectra of carbonaceous materials within the black fault rocks in Kodiak accretionary complex
Raman spectra were obtained using a Renishaw InVIA Reflex microspectrometer (ISTO-BRGM; Orléans) with 514 nm laser. The laser beam power at sample surface was set to ~0.5 mW. Analysis was performed to traverse internal textures of the BFR. Spectra was decomposed into five peaks, center positions around 1350 cm-1 (D1, D3 and D4) and graphite bands centered around 1580-1600 cm-1 (D2 and G). Microstructures of the BFR were observed under cathodoluminescence microscope.
Although D1-band develops within the crystalline microlayers of aphanitic BFR, which is thought to be melt-origin pseudotachylyte (Meneghini et al., 2010), development of G-band was not detected even in the crystalline microlayers. This observation suggest that Raman spectra of CM do not reach the equilibrium in the case of short-time heating, as pointed out by Nakamura et al. (2017). An alternative possibility is that Kodiak BFR has formed temperatures of <400 degrees C, without frictional melt.