Colored image showing the movement of the Reunion volcanic hotspot, whose flows likely covered the ancient micro-continent of Mauritia. Full image available at GFZ Potsdam.
It's not often that new pieces of continents are found, which makes research just published in Nature Geoscience rather exciting. According to the authors, there's geological evidence of a micro-continent lying under the islands of Reunion and Mauritius in the Indian Ocean.
The fragment, called Mauritia, is thought to have previously been connected in between what became India and Madagascar. As the former landmass, which included the Seychelles, split up and drifted apart, Mauritia splits off on its own. Around 85 million years ago it sank under the Indian Ocean, and the same lava flows that produced islands like Mauritius masked its presence.
A render of the ancient landmass connecting India, Madagascar,
Mauritia, and the Seychelles as it may have looked around 750
million years ago. Via Trond et. al
The multinational team behind the research studied the composition of sand on Mauritius. While the sand itself dated back to volcanic eruptions around 9 million years ago, they also found samples of the mineral zircon dating back to between 1970 million and 660 million years ago. The team argues that such zircons must have been dragged up to the surface by geologically-recent lava flows, which suggests that Mauritia is indeed lying below the top-most crust in the region, perhaps just six miles down.
The Seychelles lend support to the idea that an ancient continental fragment connected India and Madagascar. The Seychelles are made of very old rock, and the new evidence suggests that they might have been part of a larger landmass that fragmented from India and Madagascar.
"At the moment the Seychelles is a piece of granite, or continental crust, which is sitting practically in the middle of the Indian Ocean," lead author Trond Torsvik of the University of Oslo told the BBC. "But once upon a time, it was sitting north of Madagascar. 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."
The team was able to model how the various fragments drifted apart, and showed that certain fragments drifted over the volcanic hotspot that created the island of Reunion. That suggests that more fragments may exist in the region buried under more recent lava flows. As of now, there's no firm evidence that there are more micro-continents in the Indian Ocean than thought, but with further investigation, they're likely to be found.