Hidden Micro-Continent Found!

Have scientists uncovered an ancient “micro-continent” off the coast of Mauritius, an island in the Indian Ocean? According to a February 2013 report in the scientific journal Nature Geoscience, they think they have.

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First Clues

University of Oslo, Norway, geologist Ebbe Hartz  reported the discovery of twenty ancient zircon grains in the underwater sand dunes just off the island’s shore. He and his colleagues dated the zircon mineral to between 660 million and 1,970 million years old.

Next they poured over satellite images of the Earth’s magnetic fields, especially in the area around Mauritius. The Earth’s crust isn’t uniformly deep; there are thicker areas around the planet, and thinner areas, and degrees of thickness in between those ranges.

If I’m understanding the data correctly, usually, a thicker depth on an area of Earth’s crust indicates a continent.

Onto Gravity Fields

The gravity fields vary around the planet as well. Hartz said, “Zircons are heavy minerals and the uranium and lead elements used to date the ages of these zircons are extraordinarily heavy, so these grains do not easily fly around – they did not blow into Mauritius from a sandstorm in Africa.”

He added, “We also chose a beach where there was no construction whatsoever – that these grains did not come from cement somewhere else. We were also careful that all the equipment that we used to collect the minerals was new, that this was the first time that it was used, that there was no previous rock sticking to it from elsewhere.”  The photo below shows a section of coastline off the island of Mauritius.

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They Interpret the Data

So what does this all mean? The research team discovered, as a result of the zircon-dating and the gravity field data, that Mauritius was probably part of a very large swath of unusually thick Earth’s crust that arched up and around towards the Seychelles Islands. They feel this evidence suggests that Mauritius and it’s other island counterparts in the area sit over a larger, deeper micro-continent.

The scientists named the micro-continent Mauritia, and they believe the shards of ancient zircon they found belong to this ancient, albeit submerged, land mass.

What Happened to Mauritia

Further study of marine fracture zones and ocean magnetic anomalies pointed to the likelihood that Madagascar and Mauritia split sometime between 61 million and 83.5 million years ago. Thereafter Mauritia was submerged and covered with lava.

Hartz added, “There are all these little slivers of continent that may peel off continents when the hotspot of a mantle plume passes under them. Why that happens is still mind-boggling. Why, after something gets ripped apart, would it rip apart again?”

Maybe with time, science will have all the answers. But for now I’m wondering, could something similar have happened to Atlantis? Could that fabled land be covered up by millions of years of volcanic sediment too? We may never know that one, but at least we can enjoy the discovery of these other wonderful places and be free to wonder what they must have looked like way back when.

Til the next time!

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