Continental-scale rotational extension shaped lithospheric architecture in East Antarctica

Our recent analyses of major bedrock topographic lineaments across a large sector of East Antarctica reveal a distinctive radial structural pattern where predominantly triangular basins, arranged in a broadly north-south fan-like geometry, define the East Antarctic Fan-shaped Basin Province. Within this province, the Wilkes and Aurora basins appear segmented by two semi-circular belts that generate an apparent symmetric transverse offset in the basins and adjacent crustal blocks. The radial structures are also aligned with major fracture zones of the Southeast Indian Ridge, suggesting a genetic link between the onshore radial pattern and subsequent oceanic Australia/East Antarctica rifting. To assess the extent and the larger scale linkages between the inferred rotational extension and tectonic processes, we conducted a statistical analysis of preferred lineament orientations extracted from bedrock topography, magnetic, and gravity datasets. Our results indicate that the radial pattern extends across much of East Antarctica and is expressed in the lithospheric architecture, as supported by magnetic and gravity signatures and independent recent seismic modelling. We propose a tectonic model in which continental-scale rotational extension was superimposed on the inherited East Antarctic lithospheric architecture, imprinting a first-order radial structural grain. Key questions remain regarding the timing and origin of the inferred rotational extension, whether it was long-lived and diachronous (Mesozoic to early Cenozoic?), and how inherited Precambrian and younger structures were influenced by, guided or amplified the pattern. Answering these questions and testing our rotational hypothesis will require: (i) improved aerogeophysical and seismological imaging of the East Antarctic interior and targeted reinterpretation of key triangular basins (e.g. Lake Vostok, Adventure Trench and Lake Snow Eagle); (ii) better geological constraints on timing and strike-slip displacements along the inferred circular fault belts, especially where Transantarctic Mountains outcrops permit direct testing; and (iii) geodynamic and analogue modelling, including the role of dynamic mantle flow.