Tracing the evolution of the Transantarctic Basin (southern Gondwana) through sandstone petrography

The analysis of clastic sequences is fundamental for understanding plate dynamics, as it record variations in depositional environments and source-to-sink systems. Since the late Paleozoic, contemporaneous with the convergence between the paleo-Pacific plate and Gondwana, sedimentary basins developed in both forearc and retroarc positions of the Gondwanide orogenic system. The Beacon Supergroup in Antarctica and the Parmeener Supergroup in Tasmania represent the sedimentary infill of the Transantarctic Basin, located in a retroarc setting. These successions are mainly composed of fluvial sandy and muddy deposits, which are poorly deformed and currently unconformably overlie older units. Deposition began in the Devonian and ended in the Early Jurassic, spanning more than 200 Myr and encompassing  key events in the history of the Earth, such as the Late Paleozoic Ice Age, the subsequent transition from icehouse to greenhouse conditions, and the Permian-Triassic mass extinction. The composition of sandstones within the Beacon and Parmeener supergroups varies through time and space, correlating with major tectonic processes driven by subduction dynamics, which ultimately controlled the source-to-sink systems feeding these clastic units. Variability in sandstone composition is documented through a quantitative analysis of all available published data, integrated with new datasets from the Transantarctic Mountains and Tasmania. The results reveal a shift from quartz-feldspar-dominated sandstones, indicating derivation from crystalline basement, to volcanic lithic fragment rich sandstones, reflecting a provenance from coeval volcanic arc rocks. This provenance shift occurred diachronously along the basin, whit volcanic component appearing in the central Transantarctic Mountains during the Permian and in Victoria Land and Tasmania during the Triassic. Sandstone composition further indicates that the Victoria Land region evolved from an intracratonic basin in back-bulge position to a foredeep basin setting.