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The eastern part of Antarctica is buried under a thick layer of ice. Some scientists simply assumed that under this cold mass, there was nothing more than a "frozen tectonic block", a somewhat homogeneous mass that distinguished it from the mixed geologies of other continents.
But with the help of data from an abandoned European satellite, scientists have now discovered that East Antarctica was actually a cemetery of continental relics. They created beautiful 3D maps of the tectonic underground world of the southernmost continent and discovered that the ice concealed the wreck of the spectacular destruction of an ancient supercontinent.
The researchers, led by Jörg Ebbing, a geophysicist at the University of Kiel in Germany, announced their discovery earlier this month in Scientific Reports.
The results are based on data from the GOCE (Gravity Field and Steady State Ocean Circulation Explorer) satellite, which orbited around the Earth at an altitude of 155 miles until the end of 2013, when it returned to the atmosphere at the end of his mission. Nicknamed the "Ferrari of Space", this elegant instrument could measure the gravitational fields that weave through the crust and mantle of the Earth.
Kate Winter, who studies the Antarctic glaciers at Northumbria University in England and did not participate in this study, said the GOCE satellite data "helped us to replenish the supercontinent with beautiful detail."
GOCE's eye has revealed that East Antarctica is a puzzle made up of at least three geological titans called cratonic provinces. The cratons (from the Greek "kratos", which means "force") are stable rock nuclei of continents that have survived hundreds of millions of years of destruction by the tectonic plates of the Earth.
A craton has geological similarities to some of the bedrock of Australia, while another resembles a part of that of India. The third is a fusion of pieces of old seabed.
Fausto Ferraccioli, Senior Geophysicist of the British Antarctic Survey and co-author of the study, said that "when and how all of these provinces came together to constitute East Antarctica, as we see it today, remains a subject of speculation and debate ".
The pieces may have been assembled a billion years ago, when building the supercontinent Rodinia, or even 500 million years ago, when another supercontinent, Gondwana , has come together. In any case, what was discovered under Antarctica is part of what remains after the dissolution of Gondwana about 160 million years ago.
Antarctica has been described as the least understood continent on the planet and many mysteries remain about its underground world. Magnetic and seismic data, as well as ground penetrating radars attached to aircraft, can be seen through the 2-km-thick layer of ice covering 98 per cent.
This is where GOCE (pronounced GO-chay) from the European Space Agency makes history. The intensities of the gravitational field vary according to the objects with which they are associated and GOCE, with its ultrasensitive gravity probe and its proximity to the Earth's surface, could detect deep masses beneath the icy surface of Antarctica with breathtaking details.
"The beauty of GOCE lies in the fact that we can go deep into the lithosphere to go to the roots of continents," Ferraccioli said.
Winter said that despite these discoveries, the exact geologic composition of the most inland Antarctic land, located in East Antarctica, "remains to be discovered". One solution would be to drill in the heart of the continent and taste the rock directly, with the help of GOCE data maps to guide scientists in search of the perfect place to dig.
It is important to know the rock on which the world's largest ice cap is located in a global warming world, as subglacial geology influences how ice moves with climate change. But this study has more important implications that go much further in our understanding of our world.
Plate tectonics is the engine of our planet. It forges volcanoes, feeds atmospheres, digs ocean basins and creates mountain ranges. We can not understand the whole evolution of the Earth if we can not complete the puzzle and the dead satellite data have allowed us to discover some of its missing pieces.
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