Thirty samples from the Tertiary, Cretaceous and pre-Cretaceous were examined for organic matter type and abundance and maturation level. The source potential of the Lower Cretaceous is fair to good, but the deepest part of the Eumeralla Formation shows good source potential, if the abundant coal is included in the assessment. Although these sediments only reach marginal maturity, the maceral associations indicate that considerable hydrocarbons from the early phase of generation may have been generated. The presence of alginite rich oil shale in the ?pre-Cretaceous suggests that very good source rocks are present in sediments directly overlying basement.