The sandstones of the Early Triassic non-marine Rewan Group in the southern Bowen Basin represent a potential reservoir for hydrocarbons. They are mainly lithic in nature, with a large proportion of volcanic rock fragments and contain quartz grains of variable size and an authigenic clay matrix. The results of petrographic analysis show a dual provenance basin-fill pattern (cratonic–volcanic). Reservoir qualities vary considerably, but are best developed in the Quartzose and Conglomerate Intervals where partial quartz cement retarded compaction and secondary porosity developed by dissolution of labile material and flushing of clay minerals. The presence of different clay minerals in pore networks may have a significant impact on petrophysical properties of the reservoir and hence affect reservoir productivity.