Tag Archives: ocean

Earth recycles ocean floor into diamonds

Most diamonds are made of cooked seabed.

The diamond on your finger is most likely made of recycled seabed cooked deep in the Earth.

Traces of salt trapped in many diamonds show the stones are formed from ancient seabeds that became buried deep beneath the Earth’s crust, according to new research led by Macquarie University geoscientists.

Most diamonds found at the Earth’s surface are formed this way; others are created by crystallization of melts deep in the mantle.

In experiments recreating the extreme pressures and temperatures found 200 kilometres underground, Dr Michael Förster, Professor Stephen Foley, Dr Olivier Alard, and colleagues at Goethe Universität and Johannes Gutenberg Universität in Germany, have demonstrated that seawater in sediment from the bottom of the ocean reacts in the right way to produce the balance of salts found in diamond.

The study, published in Science Advances, settles a long-standing question about the formation of diamonds. “There was a theory that the salts trapped inside diamonds came from marine seawater, but couldn’t be tested,” says lead author Michael. “Our research showed that they came from marine sediment.”

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Spying on the denizens of the Southern Ocean

Sonar and satellites reveal the fish and other creatures that live far below the surface

The depths of the ocean still hold great mysteries. At depths between 200 and 1000 metres live creatures that, taken altogether, weigh as much as 10 billion tonnes.

Rudy Kloser, an expert on echo sounding and deep-sea ecosystems at CSIRO in Hobart, says these creatures are vital but poorly understood.

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Saving seagrass sanctuaries

Seagrass meadows provide food and habitat for everything from dugongs and birds to fish and tiny crabs.

Using maths to protect seagrass meadows and the communities they support .
Using maths to protect seagrass meadows and the communities they support .

Globally we’re losing over 100 sq. km per year due to dredging, coastal developments and runoff. That’s bad news for the animals they support, and bad news for us too, as seagrass supports healthy coastal fisheries as well as acting as a carbon store.

To see how seagrass can be given a fighting chance, Dr Paul Wu at the ARC Centre of Excellence for Mathematical and Statistical Frontiers and collaborators have put an extended modelling technique to new use, predicting seagrass health and suggests how some modified human activities could reduce the damage.

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