AN INTEGRATED APPROACH TO THE STUDY OF THE EARLY TRIASSIC REWAN GROUP, BOWEN BASIN

Abstract

This study of the Early Triassic Rewan Group in the Bowen Basin was an integrated approach using seismic stratigraphic principles with outcrop, wireline log, bios- tratigraphy and core data. It resulted in a coherent and useable stratigraphic framework that assisted in defining facies and potential reservoirs below seismic resolution within the Rewan Group. The Rewan Group consists of the Sagittarius Sandstone and Arcadia Formation. Depositional systems of the Sagittarius Sandstone and Arcadia Formation were affected by major tectonic and climatic changes. Each formation is marked at its base by a third-order sequence boundary. The Sagittarius Sandstone is overall regressive and was deposited in a domi- nantly lacustrine environment. The base of the overlying Arcadia Formation is marked by the Brumby Sandstone Member. It was deposited in a fluvially dominated shoreface setting. Red beds of fluvial origin in the Arcadia Formation are characterised by overbank fines and lenticular channel sandstone. High-frequency incised valley fills occur in the uppermost Arcadia Formation. The Arcadia Formation is in turn erosively overlain by pebbly sandstone of the Clematis Group. Sandstone-filled incised valleys at the base of the Sagittarius Sandstone and in the upper Arcadia Formation offer the best reservoir potential in the Rewan Group.