Antarctica is seemingly cut off from the rest of the world, separated by the vast waters of the Southern Ocean. But this was not always the case: about 200 million years ago, Antarctica was connected to other continents and together they formed the supercontinent Gondwana. Using geology, researchers were able to determine where these land masses had been connected. But the ice caps of Antarctica did not allow more precise geological determinations. Now, with satellite help, a research team has been able to paint a clearer picture, discovering high-resolution details about the “missing links” between Antarctica and its neighbors.
The research team led by geophysicist Professor Jörg Ebbing of Kiel University was able to combine magentic data from Antarctica and other continents using images from the “SWARM” satellites of the ESA (European Space Agency) and compare them with decades of geophysical data series produced by aircraft overflights. This allowed the team to time travel back 200 million years into the past and show how and where Antarctica formed with neighboring continents to form the supercontinent Gondwana. The team also succeeded in closing previously known gaps. One area in particular, between East Antarctica and Southeast Africa, was practically like two pieces of a jigsaw puzzle.
The results of the work, published in the journal Scientific Reports, are a new way to collect geophysical data despite thick ice masses. “With the old data, we had a patchwork of different stamps, so to speak, which, when put together, produced a picture – but with white spots. The satellite has now taken new images of these white areas,” explains Professor Ebbing. The results were visualized by PhD student Peter Haas and show how Antarctica and the neighbouring continents had separated. But the results go even further. This is because Antarctica’s new magnetics data can also be used to determine the movements of the ice sheets, says Professor Ebbing. This in turn helps to create even more accurate climate models for the complex processes in Antarctica with regard to climate change.
The data from the satellite measurements were processed with aerogeophysical data and compared with the known geology of Antarctica and its neighbours. These previously used data have been quite useful in understanding the separation of Antarctica, which has contributed significantly to the formation of the ice caps. But pieces of the puzzle kept missing. “We have been trying for decades to piece together the connections between Antarctica and other continents,” explains Dr. Fausto Ferraccioli of the Oceanographic and Geophysical Institute in Trieste and co-author. “We knew that magnetic data play a pivotal role, because one can peer beneath the thick Antarctic ice sheets to help extrapolate the geology exposed along the coast into the continent interior.” But it was only with ESA’s SWARM satellites that large-scale and more precise measurements of the geology via its magnetic anomalies and a comparison with the neighbouring continents of Australia and Africa were possible. Thus the parts of the continents fitted together more precisely.
ESA’s SWARM satellites are three identical satellites that have been orbiting the Earth in polar orbits at an altitude of around 480 kilometres since 2013. The satellites need between 93 and 94 minutes per orbit. Each satellite is only 75 centimetres wide, but 1.3 metres high and 9 metres long. On their way they measure the magnetic signals of the earth, from the earth’s core to the magnetosphere. Since 2018, the mission has been supported Canadian satellite Cassiopeia. In doing so, the researchers can take a look at hidden structures such as those under the ice sheets of Antarctica or the deep-sea floors of the oceans. Depending on the magnetic fingerprint, statements can be made about the geology. This reveals what Antarctica’s ice has kept hidden for millions of years.
Dr Michael Wenger, PolarJournal
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