At mid-ocean ridges, effervescent magma escapes thru rifts in the ocean floor to abolish unique crust. Below, partially melted, taffy-worship mantle rock spreads in opposite directions — stretching the unique crust unless it sorts an in depth valley machine surrounded by ridges of hills and mountains.
These abyssal seascapes, no longer now not like landscapes realized above sea degree, are the final locations that objects of continents could presumably well be expected to narrate up. But in a newest gaze published in Science Advances, researchers have realized that it’s a ways indeed seemingly: Newly dated rocks from the Southwest Indian Ridge, situated between Africa and Antarctica, are no longer most effective remnants of a continent; additionally they’re obsolete enough to give a prefer to the hypothesis that vital of Earth’s continents fashioned early on and grew to grow to be “misplaced” or hidden deep below Earth’s ocean crust.
Chuan-Zhou Liu, a marine geologist on the Chinese Academy of Sciences in Beijing, visited the Woods Gap Oceanographic Institute in 2017 to salvage the rock samples dredged from the ridge beforehand. “I wouldn’t have suspected the rocks are from continents,” he says, “because they gaze worship the ones you should well presumably well most regularly accumulate on the ocean floor.”
His evaluation showed the rocks are presumably as much as 2.7 billion years obsolete — obsolete enough to had been around when Earth’s first continents fashioned. Checking out which frail continent they got here from, nonetheless, is complicated.
(Credit: Liu et al. Science Advances)
Removed and Recycled
Liu says convection currents in the mantle can transport sizable blocks of the earth’s crust, called cratons, over nice distances. One allege craton caught the researcher’s attention: “There’s proof that the ‘keel’ of the Kaapvaal craton in South Africa has been dislodged,” he says.
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The Kaapvaal craton is the closest frail continental crust to the Southwest Indian Ridge. Nonetheless it’s additionally a whopping 1,200 miles away.
To have reached the ridge, Liu and his colleagues propose that plumes of hot, rising mantle rock beneath South Africa eroded the underside of t