Characteristics of the mixed carbonate deposit of Brigadier Formation in Northern Carnarvon Basin, Australia and its depositional model

The lithology, sedimentary facies, and distribution pattern of the Brigadier Formation of the Late Triassic remain unclear up to date in the Northern Carnarvon Basin of Australia. Studies suggest that during the time of Brigadier Formation, the region was a stable gentle basement slope tectonically under a warm and humid climate and rising sea level, which is favorable to the growth of marine lives. All the conditions are conducive to the formation of the mixed carbonate of the Brigadier Formation. The Brigadier Formation is characterized by a deltaic sand-shale sequence in the southeastern part of the basin, while the northwest part of the basin is dominated by pure carbonate rock deposits. From the southeast to the northwest of the basin, the Brigadier Formation changes from clastic deposits to carbonate. Mixed deposits were then formed when the input of clastic debris decreased and the environment became weaker in water dynamics.