Rare particles give clue to ancient Earth

May 16, 2013 by Kanina Foss

(Phys.org) —Semi-precious minerals found in a bucket of sand from an island nation have cracked open a clue to the drifting movements and break-up of ancient Earth's massive continental plates.

The particles are zircons and the island – Mauritius – is now thought to be hiding a micro-continent which has been given the name Mauritia.

Zircons can be as old as four billion years and are almost never found in oceans, proving the likelihood that Mauritius sits on top of a fragment of continental plate which remained behind and was covered by huge masses of lava when Madagascar split apart from India about 90 million years ago.

Prof. Lewis Ashwal from Wits University studies the break-up process of continents. He was part of the group of from Norway, South Africa, Britain and Germany who recently announced their finding of zircons in Mauritius. They've been working in the area for 15 years.

The break-up of continents is often associated with . These giant bubbles of hot rock rise from the deep mantle and soften the from below, until the plates break apart at the hotspots. This is how Eastern Gondwana broke apart about 170 million years ago. At first, one part was separated, which in turn fragmented into Madagascar, India, Australia and Antarctica, which then migrated to their present position.

A deep mantle plume, currently situated underneath the island of Reunion, was once situated under Mauritius and appears to have played a role in the emergence of the Indian Ocean. If the zone of the rupture lies at the edge of a (in this case Madagascar/India), fragments of this land mass may be separated off. The Seychelles are a well-known example of such a continental fragment.

Ashwal and others are suggesting, based on the study of lava sand grains from the beach of Mauritius, the existence of further fragments. The contain zircons aged between 660 and 1 970 million years, which is explained by the fact that the zircons were carried by the lava as it pushed through subjacent continental crust of this age.

According to Ashwal, there are two kinds of territory in the world – continent and ocean, and each sovereign piece of continent has the right to claim 20 nautical miles beyond its ocean borders for fishing, mining, oil and other rights.

There are great implications for Mauritius if it can be shown to be a continent, and if that piece of continental plate stretches beyond the borders of the island, extending the country's claim to the ocean territory around it, possibly all the way up to the Seychelles.

Explore further: Better forecasts for sea ice under climate change

add to favorites email to friend print save as pdf

Related Stories

Study sheds light on Earth's early mantle

May 06, 2013

(Phys.org) —An international team of researchers, led by scientists at Boston University's Department of Earth and Environment, has found evidence that material contained in young oceanic lava flows originated ...

New insights into volcanic activity on the ocean floor

Jun 16, 2010

New research reveals that when two parts of the Earth's crust break apart, this does not always cause massive volcanic eruptions. The study, published today in the journal Nature, explains why some parts ...

The North American Cordillera: Constructive collisions

Apr 03, 2013

The mountain ranges of the North American Cordillera are made up of dozens of distinct crustal blocks. A new study clarifies their mode of origin and identifies a previously unknown oceanic plate that contributed ...

Recommended for you

Better forecasts for sea ice under climate change

9 hours ago

University of Adelaide-led research will help pinpoint the impact of waves on sea ice, which is vulnerable to climate change, particularly in the Arctic where it is rapidly retreating.

"Ferrari of space' yields best map of ocean currents

17 hours ago

A satellite dubbed the "Ferrari of space" has yielded the most accurate model of ocean circulation yet, boosting understanding of the seas and a key impact of global warming, scientists said Tuesday.

Researcher studies deformation of tectonic plates

20 hours ago

Sean Bemis put his hands together side by side to demonstrate two plates of the earth's crust with a smooth boundary running between them. But that boundary is not always smooth and those plates do not always ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.