They draw a three-dimensional map of the largest glacier in Antarctica

For the first time, the soil beneath Antarctica's most vulnerable megaglacier, Thwaites, has been mapped.

4 de June de 2023 14:49

The British Antarctic Survey's Twin Otter aircraft flies over Thwaites Glacier with instrumentation attached to the wing.

Published in the journal Science Advances, analysis of the geology beneath the Thwaites Glacier in West Antarctica shows there is less sedimentary rock than expected, a finding that could affect the way ice slides and slides. melts in the coming decades.

  "Sediments allow for faster flow, like sliding over mud, " explains Dr. Tom Jordan, a geophysicist at the British Antarctic Survey (BAS), who led the study, in a statement . " Now that we have a map of where they are slippery sediments, we can better predict how the glacier will behave in the future as it recedes.

The distribution of sedimentary rocks beneath the Thwaites Glacier is included in a new map of the region's geology drawn up by BAS researchers. The findings are important because the glacier, which is the size of Great Britain or the North American state of Florida, , is one of the most rapidly changing ice-ocean systems in Antarctica .

The Thwaites Glacier's contact zone with the seafloor has receded 14 km since the late 1990s. Much of the ice sheet is below sea level and is susceptible to rapid and irreversible ice loss that could raise global sea levels by more than half a meter in a matter of centuries.

The new analysis is based on aerial surveys carried out with planes equipped with radars capable of seeing rocks through the ice, as well as sensors capable of mapping minute variations in gravity and magnetism hundreds or thousands of meters below the ground and the seabed on which the glacier rests.

Researchers use these multiple data sources to compile a three-dimensional picture of features, including the type and extent of different rocks. Jordan says, "The integrated nature of the aerial surveys was one of the keys to this research. Each sensor on the aircraft provided an important but incomplete part of the picture, but by bringing them all together we were able to provide the detailed map of the underlying geology."

In doing so, the study turns back the geological clock to examine what happened when New Zealand was torn from Antarctica about 100 million years ago, long before the Thwaites Glacier formed.

  Since the base of the Thwaites Glacier is well below sea level, researchers expected that thick sediments would have been deposited there over the next few million years.Similar analyzes have been carried out on other Antarctic glaciers, which have shown that coarse sediments predominated in these systems.

But the aircraft data suggests that only a fifth of the soil under the glacier is sedimentary rock.

By Agenda Malvinas

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