With the discovery of a lost continent hidden deep in the middle of the Indian Ocean, it’s never been a sexier time to be a geologist. Here’s why.
We all lose things: our keys, our handbags but an entire continent filled with lots of trees and animals and stuff, that’s something of a completely different scale. Now however, it seems it’s possible to misplace one of the Earth’s giant continents. Okay, it’s not Atlantis, but lying below the waters of the Indian Ocean, underneath the island of Mauritius, is something much more impressive.
Mauritius is not just for lux travel seekers. Its been drawing the attention of geologists for yonks. Why? Because of one very, very curious feature: its exceptionally strong gravitational pull. Earth’s gravity is not completely uniform in this part of the world. In fact, it can be much stronger in one place, and much weaker in the other. It all depends on the density of the earthy materials in the local crust (if you wanted to know).
Our lovely neighbour in the sky, the moon is dotted with these things called mass concentrations – mascons for short –which are basically the remains of gargantuan meteorites that long ago smashed into its surface, leaving all their shrapnel as a result. The Earth has a few of these mascons too, but it’s more about plate tectonics (the movement of our planet’s crust) on our side of the Milky Way.
The theory behind this latest discovery, advanced by geoscientist Lewis Ashwal of the University of Witwatersrand in Johannesburg, is that it’s possible that Mauritius sits atop a mascon, and that its existence is the result of an entirely different and ancient landmass that shattered and sunk from view millions of years ago. Cool, huh?
In an explosive paper, published in Nature Communications, Ashwal confirms his theory with a new study focusing on 13 small grains of the mineral zircon. In terms of age, Mauritius is eight million years young, but three-billion-year-old samples of zircon collected from the island’s beaches revealed a country and continent that are much, much older.
Paradise rocks (literally!)
To cement the hypothesis, Ashwal and his team collected even more samples and used uranium lead-dating techniques to determine the age of the zircon they found. To their amazement, the samples dated back roughly three billion years, considerably older than our fave paradise in the ocean, Mauritius!
His team concluded that the zircon could not have been formed along with the much younger Mauritius; instead, it was likely blown up onto dry land when undersea volcanoes erupted, which blasted out much older rocks from subsurface crust.
So what does all this mean? Ashwal and his other geopals now conclude that a ginormous piece of land existed between Madagascar and India, which formed part of the ancient supercontinent, Gondwanaland, 200 million years ago. When the ancient supercontinent broke apart, it fractured into smaller fragments and sank beneath the water. The then-compressed and sunken land subsequently created massive underwater volcanoes, which, millions of years later, created Mauritius, and in the process, deposited oodles of zircon all over the country’s beautiful beaches.
And there you have it. The discovery of a new continent. Mind blown.
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