Scientists have discovered a fan-shaped geological region under the ice of Antarctica

An international team of scientists has described a giant fan-shaped province of subglacial basins in East Antarctica, formed as a result of the rotational stretching of the earth's crust before the breakup of Gondwana. This was reported on June 3 in the journal Nature Geoscience.

The researchers found that the vast region of East Antarctica, with an area of half the ice sheet, represents a single physiographic structure. It was named the East Antarctic Fan-shaped Basin Province. The province covers the area from Prudes Bay to the Transantarctic Mountains and from the coast inland.

During the analysis of radar sounding data, the researchers identified 30 V-shaped subglacial basins stretching from north to south. All of them fan out from a single point of rotation — the calculated Euler pole — located near the South Pole at coordinates 86.4 degrees south and 129.9 degrees East. The symmetrical axis of the fan passes through the Belgian subglacial highlands and divides the province into two sectors.

According to the proposed kinematic model, the formation of the province took place in two stages. At the initial stage, two main basins, Wilkes and Aurora, opened around the Eulerian pole in different directions. At a later stage, the increasing stretching gave rise to a system of transverse shear belts that divided both basins into three parts each. The same belts, according to the authors, caused the segmentation of the Transantarctic Mountains into three separate blocks, shifted clockwise by about 20 degrees.

Rotational stretching, according to scientists, had three major consequences for the relief and geodynamics of the region. To the west, it caused the compression and uplift of the Gamburtsev Mountains, a unique intraplate subglacial ridge with an unexpectedly young "alpine" topography. To the east, the rotated blocks of the Transantarctic Mountains pushed into the hot lithosphere of the West Antarctic rift system, which led to their differential uplift due to thermal buoyancy.

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To the north, the transurrent edge of the fan formed a lithospheric weakening zone, along which the gap between Antarctica and Australia subsequently spread, which gave the associated passive continental margins a characteristic semicircular shape.

The authors also point to a direct link between tectonics and the current dynamics of the ice sheet. The orientation of the province's longitudinal faults controls the position of the key Antarctic outlet glaciers— Totten, Vanderford, Denman, Frost, and Emery. The transverse shear belts were presumably used by the Byrd, Beardmore, Nimrod, David, and Pritsley glaciers to cut deep thrust valleys that additionally raised mountain peaks due to isostasis.

The volume of ice over the province corresponds to a rise in the level of the World Ocean by 28 m in the event of its melting. A number of subglacial basins are located below modern sea level, which, according to scientists, increases the long-term vulnerability of the East Antarctic Ice Sheet to warming.

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The rapid weakening of the Thwaites Glacier became known in December last year. Then scientists from the Earth Observation Center of the University of Manitoba and their international colleagues pointed out the development of cracks in the shear zone of the entire ice massif. They made such conclusions when studying satellite images taken from 2002 to 2022.