The latest Carboniferous to Triassic Sydney-Gunnedah-Bowen basin system in the eastern Australia is an elongate structural basin that loCates between the Lachlan Caledonian Fold Belt in the west and the New England Fold Belt in the east. Extending from the Gunnedah district in the north to the Batemans Bay in the south, the Sydney Basin is a sub-basin loCated in the southern part of the Sydney-Gunnedah-Bowen Basin system. The Permian in Sydney basin consists of sedimentary sequences of fluvial, delta, littoral and shallow marine environments, as well as volcanic rocks. In the southwest of southern Sydney basin, the Permian unconformably onlaps the highly deformed and metamorphosed Lachlan fold Belts. The Permian System from the southern Sydney Basin comprises the Lower Permian Tallaterang Group (consisting of Clyde Coal Measures and Wasp Head Formation), Shoalhaven Group (consisting of the Lower Permian Yadboro & Tallong Conglomerate, Yarrunga Coal Measures, Pebbly Beach Formation, Snapper Point Formation and the Middle Permian Wandrawandian Siltstone, Nowra Sandstone, Berry Siltstone and Broughton Formation) and the Upper Permian Illwarra Coal Measures. From the latest Carboniferous to the Middle Triassic, the Sydney-Bowen Basin had experienced different tectonic phases from a back-arc extensional regime to a typical foreland basin: a back-arc extensional phase, a passive thermal sag phase and a flexural loading and increased compressional phase.