February 25, 2013. Arthur Conan Doyle wrote that one drop of water, a man who knows how to think, may infer the existence of the entire ocean. A team of researchers from the UK, Germany and Norway confirmed this idea with regard to the continent, instead of using the drops — the grains of sand.
The article (PDF), Published in journal Nature Geoscience, scientists have consistently developed the idea that Mascarene Plateau, were once part of the supercontinent Gondwana, and now? huge underwater elevated plain, parts of which rise above the water, forming islands, together with part of Arabian-Indian ocean ridge, before were more ancient continent.
The first hint of the existence of the continent arose after there is evidence of the geological structure of several groups of islands in the Indian Ocean. It is known that while some islands (such as Atlantic Giant Greenland) consist of continental crust, Many, including Seychelles, also belonging to the Mascarene Plateau, formed a dense oceanic crust.
Meanwhile, the geology of Madagascar, Mauritius, the Maldives and the Seychelles, as well as Lakshadweep indicates that the effect of the gravitational field on the land is stronger than expected. In this case, such an anomaly can be explained by an unusually thick layer of the earth's crust in this place? at least 25 kilometers, which is typical for continental crust. Oceanic typically less than 10 kilometers.
Simulation of the motion lithospheric plates suggests that the area outlined by conventional boundaries unexplained gravity, 90 million years ago was part of the continent and was connected with the modern India. Over millions of years, the area was separated from the Indian subcontinent, and then as a result of volcanic activity appeared island.
These islands, in particular, is Mauritius, folded magmatic basalts. It is exploring the sandy beach of Mauritius, the scientists found in the sand zircon and very surprised. Chemically resistant mineral zircon is the oldest and is not typical of those places where his researchers found.
"Zircon does not fly by itself — says Professor Trond Helge Torsvik (Trond Helge Torsvik) From the University of Oslo. — I believe that these particles could not be entered from the outside, most likely, they were kept in the basalt. "
Uranium-lead dating method showed that the particles of different age ranges from 660-840 million years to 1,971 million years. This result speaks in favor of the fact that the particles came from the ancient continental crust, which is even older than the supercontinent of Gondwana, which appeared at least 750 million years ago.
According to scientists, zircon comes from the components of Mauritius basalts. As a result of volcanic activity, lava coming out on the surface of the ancient continent, could absorb particles of zircon, and then harden to form basalt. Through millions of years of weathering of zircon saw the light, hitting the beach on a sunny tropical island, where he was picked up by scientists.
Researchers believe that it is necessary to continue the search for new evidence of the existence of an unknown continent. According to them, the Indian Ocean should be littered with such "evidence." The main problem here? active submarine volcanoes: opening on the surface of the lava masks the ancient continent.