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Costa Rica rock hunt goes far below Pacific Ocean

posted 18 Apr 2011, 13:00 by Mpelembe   [ updated 18 Apr 2011, 13:02 ]

Scientists in Costa Rica set out on board ship resembling an oil platform to extract rocks close to the earth's mantle in an attempt to shed some light on climate change.

Scientists set off from Costa Rica at the weekend to drill a hole deep under the sea and directly extract rocks from record depths that could add to the understanding of climate change.

The rocks dug up from the lower part of Earth's crust in the coming weeks will be the closest anyone has come to the vast, churning part of the planet called the mantle, which lies between the crust and the core.

On a 140-meter (460-foot) ship that resembles an oil platform, the 30-member scientific team will bring back rocks from 2 kilometers (1.2 miles) beneath the sea off Costa Rica's Pacific coast.

"Getting this deep, we will access for the first time in an intact portion of the ocean's crust 'in situ' (on site), the lower part of this crust, the gabro, which are the rocks (that) cool slower from the magma which comes from partial melting of the mantle line limits and this will tell us different things about, first, how the crust is formed and which kind of processes are engaged to form this crust," explained the mission's co-chief, Benoit Ildefonse of Montpellier University in France.

An examination of rocks from the crust and mantle could shed light on how tectonic plates -- vast pieces of the Earth's crust -- are formed and how they move. When the plates move against one another they can cause earthquakes.

Scientists also think details about the composition of the lower crust might help them better understand climate change.

The world's oceans trap greenhouse gases such as carbon dioxide, making the oceans important for models that try to predict how these gases fuel climate changes from global warming to altered weather patterns.

Scientists speculate the rocks beneath the sea might also play a role in capturing carbon.

"We have models to predict this, what we don't have is someone to actually test our models and once this crust is formed, then it interacts with sea water and exchanges chemical elements with sea water and these exchanges are recorded in the rock through transformation of their mineralogy. By studying these samples we can also tell more about the extent of these exchanges and how eventually it affects the chemistry of the ocean and the global cycles of chemical elements such as carbon, for instance," added Ildefonse.

This will be the team's fourth visit to the same hole off Costa Rica, which was picked because part of the crust is especially thin there. Drilling in the location started in 2002.

Getting to the mantle could still be a decade away, the scientist said, who compared the task to a moon mission.