Fig. 4: Comparison of the southern Australian and East Antarctic conjugate margins.

a, Palaeogeographic reconstruction of India, Australia and East Antarctica at 157 Ma (ref. ⁵⁸). Labels indicate modern-day topographic features. Red polygons mark the flat surfaces around the East Antarctic margin. Black lines mark major geological boundaries correlated between Australia and East Antarctica using potential field data²⁹. b, Transects of southern Australian margin topography (red) and East Antarctic margin bed topography (black; adjusted for ice-sheet unloading). Profile locations are indicated by the yellow lines in panel a. Horizontal bars between the panels mark the extents of the major geological provinces along the transect²⁹, delineated by the black lines shown in panel a. The Indian continental margin is not analysed due to the topographic effects of the Himalayan Orogen. c, Kernel density estimation plot of the rebounded topography of the East Antarctic flat surfaces. Dashed line represents rebounded topography (compare Fig. 2b); solid line with shading represents rebounded topography shifted by −150 m. Red and blue lines show equivalent plots for the topography of southern Australia (fluvial passive margin) and Baffin Island (glaciated passive margin), respectively. d, Box plots of local-scale relief for the three regions shown in panel c, calculated using n individual point measurements. Box plots mark the mean (circle), median (central line), interquartile range (box) and 5th and 95th percentiles (outer bars).