Provenance And Tectonic Setting Of The Early Permian Sedimentary Succession In The Southern Edge Of The Sydney Basin, Eastern Australia

Early Permian basins formed during a major phase of crustal extension are common throughout eastern Gondwana. One of these basins, the Sydney Basin, has not been subjected to geochemical studies aimed at determining the sedimentary provenance and the tectonic setting. This study provides new geochemical data of the Lower Permian siliciclastic successions in the southern edge of the Sydney Basin. Published petrographic analysis indicates a source area containing sedimentary, felsic volcanic, plutonic, and low-grade metamorphic rocks. Major, trace and rare earth element data suggest that the clastic rocks are geochemically mature and originated from a continental source that has been subjected to moderate to strong weathering. Further, they indicate that most source rocks were of felsic composition and that only the oldest sediments possess a more mafic signature. The provenance data presented in this study, along with published palaeocurrent data, point to the Lachlan orogen being the main source of sediments for the basin. Multi-dimensional discrimination diagrams suggest a continental rift setting and agree with the published sequence stratigraphic framework that suggests a deepening-upward depositional trend associated with tectonic subsidence. This study documents geochemically the provenance of the sedimentary successions within the southern edge of the Sydney Basin and the continental rift origin of the basin.