10 août 2015

La naissance d'un nouvel océan


Voici comment naît un océan. Ce fut d'ailleurs le cas de l'actuel océan Atlantique qui ne fut initialement qu'une longue fissure entre l'Afrique et l'Amérique du sud, entre le Québec et l'Europe...

A 35-mile rift in the desert of Ethiopia will likely become a new ocean eventually, researchers now confirm.

The crack, 20 feet wide in spots, opened in 2005 and some geologists believed then that it would spawn a new ocean.

(...) Using newly gathered seismic data from 2005, researchers reconstructed the event to show the rift tore open along its entire 35-mile length in just days. Dabbahu, a volcano at the northern end of the rift, erupted first, then magma pushed up through the middle of the rift area and began "unzipping" the rift in both directions, the researchers explained in a statement today.

(...) The African and Arabian plates meet in the remote Afar desert of Northern Ethiopia and have been spreading apart in a rifting process — at a speed of less than 1 inch per year — for the past 30 million years. This rifting formed the 186-mile Afar depression and the Red Sea. The thinking is that the Red Sea will eventually pour into the new sea in a million years or so. The new ocean would connect to the Red Sea and the Gulf of Aden, an arm of the Arabian Sea between Yemen on the Arabian Peninsula and Somalia in eastern Africa.



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