A continent-sized discovery is lying under the island of Mauritius
Lucy Naland | Presentation Director
Scientists recently discovered an ancient microcontinent — known as Mauritia — under the island of Mauritius in the Indian Ocean.
Even though Mauritius itself is only around 8 million years old, a team of researchers from the University of the Witwatersrand in South Africa found pieces of zircon crystals that are almost 3 billion years old embedded in volcanic rocks that were found with the microcontinent.
“The difference in age is phenomenal,” said Susan Millar, associate professor of geography at Syracuse University’s Maxwell School of Citizenship and Public Affairs.
Zircon is one of the oldest known minerals on earth and was the first crystal to form as the molten granite of earth’s surface cooled into rock, according to gemselect.com. It is generally found in rocks that have been expelled from volcanoes during eruptions.
Robert Moucha, assistant professor of earth sciences in the College of Arts and Sciences at SU, said zircon is one of the hardest minerals to destroy. When zircon forms, he added, it traps radioactive uranium and lead isotopes. When the isotopes decay, they leave tracks that allow scientists to calculate when pieces of zircon were formed.
In 2013, a separate team of researchers found traces of zircon that also seemed to be billions of years old in the sand on Mauritian beaches. However, the scientific community mostly disregarded those findings because others argued that the minerals could have been blown onto the beaches from somewhere else.
Part of the reason this recent discovery of the microcontinent has been so much better received by the scientific community — when compared to the 2013 work — is that the new pieces of zircon were found in rock. This refutes any possibility that they could have been transported to the island by wind or waves, said Lewis Ashwal, a professor at the School of Geosciences in the University of the Witwatersrand, who was the lead author of the paper on the recent discovery, in an email.
Other experts had similar opinions about the impacts of the discovery. Millar said earth’s geography has always been relatively mobile and constantly continues to change because of tectonic plate movements.
“What this finding has pointed to is that it has given a bit more detail about how the planet broke apart,” she said, while also noting that the discovery might provide researchers a glimpse into how much continent has preserved or destroyed throughout the history of the Earth.
Donald Siegel, professor and department chair of the earth sciences department in the College of Arts and Sciences, said in an email the discovery doesn’t have any bearing on the Earth’s current environment.
“Environmentally, it means utterly nothing, since the old stuff has been there for billions of years and frankly isn’t going anyplace soon,” he said. “The earth’s oceans and atmosphere do their thing above it in complete innocence of the old crust below.”
Moucha agreed with Siegel, saying the discovery doesn’t have any environmental implications. But he said that combining geophysical methods of research with geochemistry could help solve some other geographical mysteries.
For example, while geophysics can tell how thick a continent is, Moucha said geophysics can’t distinguish whether the thickness is due simply to thick basalt rock or thick basalt with a sliver of continental crust. By adding geochemistry, one can tell the difference between the types of rock that make up landmasses, Moucha added.
“Moving forward, we see the merging of different fields in earth sciences to solve these problems, and this is a beautiful example of that,” Moucha said.
Published on February 13, 2017 at 9:20 pm
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