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Earth Science

Long-Lost Continent Found Under the Indian Ocean 168

Posted by samzenpus
from the calling-Cthulhu dept.
ananyo writes "The drowned remnants of an ancient micro-continent may lie scattered beneath the waters between Madagascar and India, a new study suggests. Evidence for the long-lost land comes from Mauritius, a volcanic island about 900 kilometers east of Madagascar (abstract) The oldest volcanic rocks on the island date to about 8.9 million years ago. Yet grain-by-grain analyses of beach sand collected at two sites on the Mauritian coast revealed around 20 zircons — tiny crystals of zirconium silicate that are exceedingly resistant to erosion or chemical change — that were far older. One of these zircons was at least 1.97 billion years old. The researchers that made the discovery think that geologically recent volcanic eruptions brought shards of the buried continent to the Earth's surface, where the zircons eroded from their parent rocks to pepper the island's sands. Analyses of Earth's gravitational field reveal several broad areas where sea-floor crust at the bottom of the Indian ocean is much thicker than normal — at least 25 to 30 kilometers thick, rather than the normal 5 to 10 kilometers. Those crustal anomalies may be the remains of a landmass that researchers have now dubbed Mauritia, which they suggest split from Madagascar when tectonic rifting and sea-floor spreading sent the Indian subcontinent surging northeast millions of years ago."
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Long-Lost Continent Found Under the Indian Ocean

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  • Very confusing (Score:5, Informative)

    by 140Mandak262Jamuna (970587) on Monday February 25, 2013 @12:54PM (#43004281) Journal
    The last pangea was about 300 million years ago. Indian subcontinent dashed across the Indian ocean and rammed into the underbelly of Asia just 70 million years ago. But these zircon cyrstals are 1900 million years ago. Enough time for one or two pangeas to form and break apart. The data is data, never argue with it. The crust could be 20 km thick where Arabian Sea is today and these crystals could be 1.9 billion years old. But I wish there is a better explanation than this idea of a lost continent.

    I am bracing for another assault from the Tamil literature majors. There are references to sea level rise and lost cities (South Madurai) and lost rivers (Pahtruli) and lost temples (near Mamallapuram) and lost harbours (near Poompuhar) and lost grammar books (by Agastiyar ) in Tamil. Best explained by the ending of last ice age some 9000 years ago and the seas coming in a few kilometers and probably flooding a large river delta. But these guys postulate a "lost continent" of Lemuria, exactly in the Arabian Sea./Indian Ocean. Now they are going to come on like a ton of bricks claiming vindication and "proof" that the Tamil language is 1.9 billion years old. Especially since there is a literary reference that translates as, "after the rocks have appeared, but the sand has not yet been formed, [Tamils] were born with swords, the eldest civilization". That would gel with a 1.9 billion year old language.

  • by Anonymous Coward on Monday February 25, 2013 @01:08PM (#43004431)

    its called subduction, the continents are on the tectonic plates which float and move around. The San Andreas fault in California is a prime example of subduction, the pacific plate is subducting and recycling the north american plate.

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