New research shows that rhythmic pulses of molten rocks are rising under Eastern Africa.
The pulsating plume of the hot mantle beneath Ethiopia is driven by plate tectonics, slowly pulling away from the region, forming a new ocean near the Gulf of Aden and the Red Sea, researchers reported June 25 in the journal Nature Geoscience.
“We have found that the evolution of the upwellings of the deep mantle is closely linked to the movement of the plate above,” Derek Kiel, an earth scientist at the University of Southampton and the University of Florence, said in a statement. “This has a major impact on how we interpret the processes of surface volcanism, seismicity and continental fission.”
You might like it
The mantle plume is located beneath a distant region of Ethiopia, at the intersection of three tectonic plates. All the tears between these plates are of different ages and they vary at different rates. Some are in the process of forming new oceans, while others are pulling away from the crust below Africa. However, the structure and movement of plumes, as well as the forces driving these movements, are not well understood.
Scientists have studied the chemical composition of over 130 samples of volcanic rock in the AFAR region to investigate the structure of the crust and the underlying mantle plume. These samples provided information on the depth and composition of the melted rock beneath the surface. The team also used computer models to determine how regions respond to different types of mantle plumes and compared their responses to existing geological data.
Researchers have found that a single mantle plume is beneath all three cracks, but its chemical composition is not uniform. Furthermore, molten rocks rhythmically spike upward, leaving behind different chemical features.
“The chemical stripes suggest that the plume pulsates like a heartbeat,” said Tom Gernon, a geoscientist at the University of Southampton, in a statement. “These pulses appear to work differently depending on the thickness of the plate and how quickly it is pulled apart. In faster spreading clefts like the Red Sea, the pulses move more efficiently and regularly, like pulses passing through narrow arteries.”
Changes in the spacing between stripes of various clefts suggest that the mantle plume reacts differently with the above tectonic plates. The lithosphere – the crust and upper mantle – is a thick place that blocks the flow of the mantle and is more condensed with stripes. Under the thinner lithosphere, the stripes are more wider.
The findings help scientists understand volcanic activity on the surface. “This work shows that the upwellings of the deep mantle flow under the base of the tectonic plate, helping to concentrate volcanic activity in the thinnest locations,” Kiel said in a statement.
Future work in the AFAR region could include investigating the speed of mantle flow under different plates, Keir added.
Source link
