Mantle Dynamic Topography of the Fringing Oceanic Basins of Antarctica

Dynamic mantle processes are known to influence oceanic basins with implications for ocean circulation and climate. This study exploits an interdisciplinary approach to probe present-day mantle and lithosphere beneath Antarctica's fringing oceanic basins to better understand sub-crustal processes and implications for the continental realm. To quantify dynamic topography in the Southern Ocean, observed depth to basement is corrected for isostatic loading to isolate the residual bathymetric signal, a robust proxy for dynamic mantle support. In this way, a comprehensive suite of oceanic residual depth measurements (n = 1120) are calculated from seismic reflection profiles in the Southern Ocean. This data set is correlated with free-air gravity anomalies and tomographic models to determine which region of the mantle contributes most significantly to dynamic support, with results indicating the upper 530 and 350 km, respectively. These oceanic observations also provide spatial context for onshore studies, where ice-loading and complex geological histories complicate residual elevation estimates. Rare earth element modeling of Neogene basalt samples links offshore dynamic swells and thinned lithosphere to Marie Byrd Land, the West Antarctic Rift System, and the Transantarctic Mountains, with isolated support beneath the Antarctic Peninsula. This pattern aligns with gravity anomalies and slow shear-wave velocity zones. By refining constraints on dynamic mantle support, these results offer benchmarks for geothermal models, mantle convection simulations, oceanographic studies and ice sheet reconstructions, ultimately improving our understanding of Antarctica's role in global climate evolution.