3 billion-year-old "lost continent" lurking under African island
By TIA GHOSE LIVESCIENCE.COM February 1, 2017, 11:09 AM
It’s official: A 3-billion-year-old “lost continent” lurks beneath the Indian Ocean island of Mauritius, new research confirms.
Sparkly, iridescent flecks of rocks known as zircons from Mauritius date back billions of years, to one of the earliest periods in Earth’s history, the researchers found. Other rocks on the island, by contrast, are no more than 9 million years old.
“The fact that we have found zircons of this age proves that there are much older crustal materials under Mauritius that could only have originated from a continent,” Lewis Ashwal, lead author of the new study and a geologist at the University of the Witwatersrand, Johannesburg in South Africa, said in a statement.
Earth’s crust is made up of two parts: the planet’s continents, which rise high above the oceans because they are composed of lighter rocks such as granite; and the ocean basins, which sink lower because they are made up of denser rocks such as basalt, according to a video about the new study. Whereas the continental crust may be 4 billion years old, oceanic crust is much younger, and is continually being formed as molten rock spews through fissures in the ocean floor, called midocean ridges.
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FEBRUARY 1, 2017
Ancient ‘lost continent’ fragment discovered in the Indian Ocean
by Chuck Bednar
A piece of crust that broke off from the supercontinent Gondwana approximately 200 million years ago has been found underneath the island of Mauritius in the Indian Ocean, according to new research published this week in the journal Nature Communications.
The fragment appears to have broken off from the island of Madagascar when Africa, India, Australia, and Antarctic spilt apart and formed the Indian Ocean, lead author Lewis Ashwal, a professor at Wits University in South Africa and his colleagues reported in their study.
After breaking off from the supercontinent, the piece of crust was covered by lava following volcanic eruptions on the island, and by studying the zircon content of the rocks, Ashwal’s team determined that the mineral remnants were far too old to have come from Mauritius itself.
“Earth is made up of two parts – continents, which are old, and oceans, which are ‘young,’ the professor explained in a statement. “On the continents, you find rocks that are over four billion years old, but you find nothing like that in the oceans, as this is where new rocks are formed.”
Read more at http://www.redorbit.com/news/science/1113417246/ancient-lost-continent-fragment-discovered-in-the-indian-ocean/#BViOjR2UY8VtJSRM.99
