A massive, semi-continent-sized subsurface structure has been discovered by scientists beneath Antarctica’s frozen surface.
The discovery, reported by an international team of scientists, reveals the presence of an unusually shaped feature which researchers with Durham University’s Department of Geography characterize as a “vast geological structure hidden beneath the East Antarctic Ice Sheet.”
The discovery was recently detailed in a study featured in Nature Geoscience.
A Massive Fan-Shaped Structure
Composed of several gigantic basins located beneath more than three kilometers of the southern continent’s icy exterior, the unusual structure has been dubbed the “East Antarctic Fan-shaped Basin Province.”
The massive feature is large enough to be considered continental in scale all by itself and incorporates some of the best-known subglacial features in the region, which include the famous Wilkes and Aurora basins.
The fan-shaped geological megas-structure also features the basin, which comprises Antarctica’s Lake Vostok, which is recognized as the largest subglacial lacustrine feature anywhere on the planet.
“We propose that the fan-like landscape is the product of distributed intraplate rotational extension before the breakup of Gondwana, with three continental-scale consequences,” the team writes in their study.
While the individual basins have all been characterized in past work, the international team reports that the new research marks the first time they have been studied in connection to a singular structure, which they believe was formed through the geological process of distributed rotational extension.
Origins of a Giant Subglacial Structure
At some point in Antarctica’s deep geological history, the continent’s subglacial crust spread out from a central point, resulting in the distinctive fan-shaped appearance it possesses today.
Likening the feature to an open hand, with each of the basins representing gaps between fingers, the research team says it is possible that the newly-characterized East Antarctic Fan-shaped Basin Province “could be one of the largest examples of rotational extension ever seen in continental crust.”
The question of how it formed remains a mystery, although there are several possible explanations.
One involves its formation over the course of several tectonic phases, which researchers believe may be linked to the formation of the ancient supercontinent of Gondwana. According to this theory, the present-day Antarctic land mass’s eventual separation from modern Australia may have played a key role in the breakup that formed the structure in question.
However, remaining questions about the age of the unusual feature also raise possibilities about other geological processes that could have led to its creation.
Today, the structure plays a crucial role in the movement of ice, whereby the distribution of subglacial lakes and basins is primarily governed by its shape. Researchers think this could be important because it would mean the fan-shaped feature may significantly impact the stability of regions of Antarctica that are susceptible to the effects of climate change.
Investigating a Subglacial Mega-Structure
By combining subglacial topographical studies with examinations of geological data, the researchers have tentatively concluded that deep tectonic processes within the continent’s lithosphere, comprising the Earth’s crust and upper mantle, likely played a major role in shaping the structure.
The team combined these data with observations of seismic data, gravity measurements, and magnetic readings as well to help shape the crustal and lithospheric models used as the basis for their study.
According to Durham University researchers, the orientation and elevation of the subglacial topography was calculated based on what the researchers characterize as “rebounded topography,” in which the elevation of land surfaces in East Antarctica were calculated based on how the terrain would respond if none of the ice that currently weights it down were present.
“Laterally, to the west, it caused compression and the consequent uplift of the Gamburtsev Mountains,” the team reports, while to the east, “the northernmost Transantarctic Mountains segment was rotated clockwise by ~20°, overriding the West Antarctic Rift System’s hot lithosphere,” which segmented the mountains into three distinct blocks.
Meanwhile, to the north, the team says the “transcurrent edge of the fan formed the lithospheric weakness that controlled the breakup of Gondwana by driving the propagation of Antarctica–Australia separation and shaping the resulting semi-circular passive continental margins.”
“These processes have influenced the present-day East Antarctica sub-ice landscape and the evolution of the overlying ice sheet,” the researchers say, which includes “the development of glacial troughs and outlet glaciers.”
The team’s recent study, “A fan-shaped subglacial basin province in East Antarctica formed by rotational extension,” was published in Nature Geoscience on June 3, 2026.
Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.