A massive, fan-shaped tectonic structure connecting several prominent buried basins has been discovered deep beneath the East Antarctic Ice Sheet. The system, named the East Antarctic Fan-Shaped Basin Province, likely formed during the ancient breakup of the Gondwana supercontinent. Published on June 3 in the journal Nature Geoscience, the study reveals that the Wilkes and Aurora basins, alongside the basin hosting Lake Vostok, are interconnected parts of a singular system shaped by distributed rotational extension—a process where the Earth’s crust deforms outward from a fixed central point like spreading fingers.
“Rotational extension is known from other tectonic settings, but recognizing a feature of this scale, hidden beneath the East Antarctic Ice Sheet, is quite remarkable,” explained first author Egidio Armadillo, a researcher at the University of Genoa. “If our interpretation is correct, this may be one of the largest and clearest examples of distributed rotational extension yet recognized in continental crust.”
Researchers identified the formation by analyzing subglacial landscape geology, seismic data, and gravitational models. The structure likely facilitated the separation of Antarctica and Australia roughly 70 million years ago by weakening a northern boundary zone. Armadillo noted, “The structure may have developed in more than one phase. However, we think it is likely connected to the long tectonic evolution that preceded and accompanied the breakup of Gondwana, especially the separation between Antarctica and Australia.”
