[ad_1]
"CRATON." One million billion tons. The figure, titanic, exceeds the human understanding. However, it represents the weight of diamonds on which we sit, the latter wisely waiting about 200 km from the surface. A discovery, published in the journal Geochemistry, Geophysics, Geosystems that is due to the prestigious Mbadachusetts Institute of Technology (MIT). To reach this conclusion, the researchers badyzed surprising anomalies present in decades of seismic data. Namely, the surprising tendency of seismic waves to accelerate as they pbad through rocks called "cratons", which form part of the earth's crust and upper mantle. A signature compatible with the presence of 1 to 2% of diamonds in the cratons! A number that represents 1000 times more diamonds than the previous estimates.
"Diamond may not be exotic, if it is so common geologically"
But it is not necessary to expect new mines: this mbad of precious stones is 145 to 240 kilometers below the surface of the planet, well beyond the distances reached by drilling today. "We can not reach them but there are many more diamonds than we thought ", Ulrich Faul, a researcher in the Department of Planetary, Atmospheric and Earth Sciences at MIT, said in a statement. "This shows that the diamond may not be this exotic mineral, but at the geological level it is relatively common ," he added.
SOUND SPEED ] In fact, the researchers simulated by computer the crossing of seismic waves of different combinations of rocks and ores. The challenge: to determine the speed of the seismic waves, and thus identify the compositions that could correspond to the observed acceleration. However, "the diamond is particular continues Ulrich Faul One of its properties is that the speed of sound is more than twice as fast as in the main ore of the rocks of the upper mantle , olivine ". Hence the conclusion of the geoscientists: the seismic signature of the cratons is compatible with a diamond content of 1 to 2%.
An inaccessible treasure
"We examined all possibilities from every angle, and it is the only one that seems reasonable to us " completes the researcher. These diamonds, however, should remain hidden in the depths of the Earth for some time: made of carbon, they are formed under very strong pressure and extreme temperature deep in the Earth. Imagine: the pressure must reach tens of thousands of atmospheres, for more than 1000 ° C! They then only near the surface through rare volcanic eruptions. Suffice to say that no burglar of jewelry is close to get their hands on this fantastic magot …
With AFP
Source link
