Stratigraphy of the upper carboniferous and lower permian sequence, southern Sydney Basin

Abstract

A study of the stratigraphic units within the southern Sydney Basin has led to the recognition of Upper Carboniferous and Lower Permian sediments. Terrestrial valley-fill sediments up to 228 m thick define a palaeodrainage system active during the Upper Carboniferous. These sediments belong to the proposed Talaterang Group and comprise the Yadboro Conglomerate, Tallong Conglomerate, Burrawang Conglomerate, Yagers Conglomerate, Pigeon House Creek Siltstone, and Badgerys Breccia. Palynological data indicate that at least the lower part of the Talaterang Group can be correlated with the Seaham Formation of the Hunter Valley. The Talaterang Group is overlain disconformably by the Clyde Coal Measures (up to 41 m thick) and the Yarrunga Coal Measures, which are in part laterally equivalent to, and overlain by, the Conjola Sug-Group (lower part of the Shoalhaven Group). The Clyde Coal Measures may be correlated with the interval extending from the Rutherford Formation to the Greta Coal Measures of the Hunter Valley. Marine terrigenous sediments of the Conjola Sub-Group (420 m thick) were deposited during a transgression which began in the Early Permian (Allandale equivalent to, and overlain by, the Conjola Sub-Group (lower part of the Shoalmation, Pebbley Beach Formation, and Snapper Point Formation, and are in turn overlain by the Ulladulla Mudstone and Wandrawandian Siltstone (together up to 120 m thick); they were derived from the west and south, and were deposited in a shallow marine shelf environment into which exotic megaclasts were ice-rafted.