Brett Smith for redOrbit.com – Your Universe Online
Tales of submerged or ℠lost´ areas of land have been prevalent in popular culture since the days of Plato. Yet, while we never found the lost city of Atlantis, an international group of scientists has found evidence of an ancient micro-continent resting beneath two islands in the Indian Ocean.
Until around 750 million years ago, all of the dry land on Earth was collected into a single continent called Rodinia, the older supercontinent counterpart to the more well-known Pangaea. The supercontinent was driven apart by tectonic forces, slowly fragmenting and drifting apart some 750 million years ago.
New evidence suggests at least one landmass got lost in this continental ballet that occurred millions of years before the emergence of man. According to a new report in Nature Geoscience, a strip of land, which scientists have dubbed Mauritia, linked the landmasses that would later become modern day India and Madagascar between 2,000 and 85 million years ago.
The team of British, Norwegian, South African and German scientists made this discovery while studying grains of sand from the beaches of Mauritius, a tiny yet popular tropical island in the Indian Ocean. Using lead-uranium dating techniques, the team was able to date the grains back to a volcanic eruption that occurred around nine million years ago, yet they contained minerals that were between roughly 600 million and 2 billion years old.
“We found zircons that we extracted from the beach sands, and these are something you typically find in a continental crust,” co-author Trond Torsvik of the University of Oslo, Norway told BBC News. “They are very old in age.”
After a recalculation of geohistorical plate tectonics, the team was able to explain how and where the fragments ended up on Mauritius. They said that large plumes of magma rise from deep within the Earth and soften the tectonic plates from below until the plates break apart at the hotspots.
“On the one hand, it shows the position of the plates relative to the two hotspots at the time of the rupture, which points towards a causal relation,” said Bernhard Steinberger of the GFZ German Research Centre for Geosciences in Potsdam, who also co-authored the report. “On the other hand, we were able to show that the continent fragments continued to wander almost exactly over the Reunion plume, which explains how they were covered by volcanic rock.”
Torsvik said that pieces of Mauritia might be located about 6 miles beneath the Indian Ocean and around Mauritius. About 85 million years ago, the microcontinent broke up and eventually disappeared beneath the waves.
“But once upon a time, it was sitting north of Madagascar,” Torsvik noted. “And what we are saying is that maybe this was much bigger, and there are many of these continental fragments that are spread around in the ocean.”
“We need seismic data which can image the structure,” Torsvik said. “Or you can drill deep, but that would cost a lot of money.” He says that future studies of the area will be focused on finding out more details about the lost landmass.
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