Petrological and geochemical characterization of Candiota coal seams, Brazil - Implication for coal facies interpretations and coal rank

Results from geochemical analyses showed that terrestrial organic matter is predominant as indicated by hydrogen and oxygen indices, carbon preference indices and the sterane distribution. Geochemical maturity parameters such as the 20 S / (20 S + 20 R) and αββ / (αββ + ααα) ratios for C29 regular steranes support the low level of rank (maturity) as indicated by the vitrinite reflectance measurements (0.41-0.45%) and gross calorific values (< 24 MJ/kg, m, af).