Researchers have identified a massive hidden geological feature beneath the East Antarctic Ice Sheet, revealing a previously unrecognized connection between some of the continent’s largest buried landscapes.
The newly recognized structure consists of a network of enormous basins concealed beneath ice that exceeds three kilometers (nearly two miles) in thickness in some locations.
Together, these basins form a continent-scale fan-shaped pattern that researchers have named the East Antarctic Fan-shaped Basin Province.
The province encompasses several well-known subglacial features, including the Wilkes and Aurora basins, as well as the basin containing Lake Vostok, the largest known subglacial lake on Earth.
Although scientists have studied many of these basins individually for years, this is the first time they have been recognized as parts of a single, interconnected geological structure.
Evidence of Ancient Crustal Stretching
According to the research team, the structure likely formed through a process known as distributed rotational extension.
This occurs when continental crust gradually stretches outward from a central point. Researchers compare the pattern to a hand, where the base of the thumb remains fixed while the fingers spread apart. The spaces between the fingers resemble the triangular basins created as the crust extends.
The East Antarctic Fan-shaped Basin Province may represent one of the largest examples of rotational extension ever identified within continental crust.
Scientists believe the structure developed through multiple tectonic episodes associated with the formation and evolution of the ancient Gondwana supercontinent. It may also be linked to the later separation of Antarctica and Australia and could even have played a role in that continental breakup.
The discovery raises several new questions, including when the structure formed and what geodynamic processes were responsible for creating it.
Implications for Antarctica’s Ice Sheet
The importance of the finding extends beyond reconstructing Antarctica’s geological past.
The shape of the bedrock beneath the ice continues to influence how ice moves across the continent today. This hidden landscape helps determine the location of subglacial basins and lakes and may affect the stability of regions of the Antarctic Ice Sheet that are particularly vulnerable to climate change.
Mapping Antarctica’s Hidden Landscape
To investigate the newly recognized structure, researchers combined multiple sources of data, including subglacial topography, geological observations, gravity measurements, magnetic data, seismic information, and models of the crust and lithosphere.
Their analysis indicates that the feature is the result of deep tectonic processes operating within the Antarctic lithosphere.
Dr. Guy Paxman from the Department of Geography was a member of the international research team.
He led calculations estimating how East Antarctica’s landscape would appear if the entire ice sheet were removed (which would cause the land to rebound upwards by as much as one kilometer).
This reconstructed “rebounded topography” allowed researchers to examine both the elevation and orientation of the newly identified geological structure.
The study was led by Dr. Egidio Armadillo of the University of Genoa and was supported by the Italian National Antarctic Research Program.