Coal rank variation in the Bowen Basin, Queensland

Abstract Isoreflectance maps for selected stratigraphic horizons in the Bowen Basin show regular rank trends, and there is general parallelism between reflectance contours and structural contours in the Basin. These features imply that coalification is due to a rise of temperature with increasing depth of burial. Depth-reflectance profiles calculated from coal-bearing horizons across the Basin show that reflectance increases with depth, and reflectance gradients increase with increasing reflectance. Coal rank in the Bowen Basin is interpreted to be due to increased temperatures due to burial under conditions of high geothermal gradient during the Permo-Triassic.