Scientists Just Discovered a Giant Fan-Shaped Structure Buried Under Antarctica’s Thickest Ice

A new geological feature stretching hundreds of kilometres beneath East Antarctica has been identified, linking several well‑known subglacial basins into a single, expansive formation. The overlying ice sheet can exceed three kilometres in thickness, concealing one of the most extensive examples of continental extension ever documented.

Researchers have named the structure the East Antarctic Fan-shaped Basin Province. It integrates the Wilkes basin, the Aurora basin and the basin that houses Lake Vostok—the planet’s largest known subglacial lake. While each basin has been mapped individually, this study is the first to present them as components of a unified, massive system.

Beyond a simple cartographic revision, the fan‑shaped layout influences ice dynamics and the distribution of subglacial lakes, with potential repercussions for the stability of the Antarctic Ice Sheet. The province’s morphology results from rotational extension, a process in which the crust spreads outward from a central pivot, producing the hand‑like pattern observed today.

Revealing a Hand‑Like Network Beneath the Ice

According to a statement released by Durham University, the province consists of several colossal subglacial basins arranged like an open hand, with the palm representing a central hub and the “fingers” spreading outward. The triangular spaces between the fingers correspond to the individual basins.

Iconic Antarctic features are now recognized as parts of this system. For instance, Lake Vostok lies beneath a thick ice cover and had been studied in isolation; its connection to the Wilkes and Aurora basins emerges only with this new interpretation.

Viewing the basins as a single entity uncovers patterns of crustal stretching that were previously hidden, offering a clearer picture of the hidden geology beneath the continent.

Rotational Extension as the Engine Behind the Fan

The authors explain that the province arose through distributed rotational extension, a mechanism where continental crust spreads outward from a central point. The resulting fan shape marks zones where the crust has been elongated and thinned over geological time. The study, published in Nature Geoscience, suggests this may be one of the largest documented instances of rotational extension in continental lithosphere.

Multiple tectonic episodes linked to the breakup of the Gondwana supercontinent and the subsequent separation of Antarctica from Australia likely contributed to the province’s development. This connection implies that the fan‑shaped basins not only preserve ancient tectonic history but may also have steered the continental rifting process.

Implications for Ice Dynamics and Bedrock Elevation

To map the hidden province, scientists combined high‑resolution subglacial topography with gravity, magnetic and seismic observations, alongside models of the crust and lithosphere. Dr. Guy Paxman, a co‑author, notes that removing the ice sheet would cause the underlying terrain to rebound by up to a kilometre—a phenomenon known as rebound topography.

This uplift information helped the team resolve the orientation and depth of the individual basins. The researchers stress that the fan‑shaped structure continues to steer ice flow and influences where subglacial lakes can form, linking ancient tectonic forces to the present‑day behaviour of the ice sheet.