R8: Metamorphic rocks and tectonics

[R8-05] Structural and chemical evolution of carbonaceous materials in Archean low to medium grade metasedimentary rocks

*KIRAN Sasidharan¹, Nakamura Yoshihiro², Satish-Kumar Madhusoodhan¹, Ohfuji Hiroaki³ (1. Niigata Uni., 2. Geological Survey of Japan, AIST, 3. Tohoku Uni.)

Keywords:Carbonaceous material, Micro-Raman spectroscopy, Deep UV Raman spectroscopy, Carbon isotope

The organic matter trapped in the sedimentary rocks that attain maturity during prograde metamorphism is known as carbonaceous material. Structural and chemical changes in CM due to medium-grade metamorphism and post-metamorphic hydrothermal alteration were observed with the aid of micro-Raman spectroscopy and carbon isotope systematics in Dharwar Craton, India. To study the evolution of low-grade CM, stromatolite sample (Tumbiana Formation, Pilbara Craton) with highly depleted C-isotope ratio is selected that attained global attention in terms of Archean methanogenesis.