R8: Metamorphic rocks and tectonics

[R8P-08] Sulfur isotope study of metacarbonate rocks from Highland Complex, Sri Lanka

*Aoi Yohioka¹, Satish-Kumar Madhusoodhan², Kosuke Goto ³, Gen Shimoda³, Sanjeewa P. K. Malaviarachchi⁴ (1. Grad. Sch. Sci. Tech., Niigata Univ, 2. Fac. Sci., Niigata Univ., 3. AIST-GSJ, 4. Univ. Peradeniya, Sri Lanka)

Keywords:sulfur isotopes, metamorphism, microbial sulfate reduction, Highland Complex, Sri Lanka

Sulfur isotope ratios of pyrite in carbonate rocks retain changes in marine sulfate reservoirs associated with sedimentary environments and elevated oxygen concentrations. Pyrite in Sri Lankan meta-carbonate rocks exhibits high δ³⁴S values reflecting microbial sulfate reduction (MSR). Comparison of sulfur isotope ratios with unmetamorphosed carbonate rocks shows similar sulfur isotope values, suggesting that metamorphism has no effect on sulfur isotope ratios. Thus, carbonate rocks may provide important information for paleoceanography.