The so-called Great Rift Valley in Africa is the largest continental rift on the planet and has been deforming the Earth, geologists do not quite understand why this is happening, as it does not behave like any other rift in the world. But a new study from Virginia Tech’s Department of Geosciences appears to have found an explanation.
The Great Rift Valley
When a geologically significant rift exists, it is known that they are usually caused by tectonic plates moving away from each other, causing the lithosphere (the layer of the planet comprising part of the Earth’s crust and mantle) to stretch and pull apart. The immediate consequence is the appearance of deformations on the Earth’s surface, which generally form perpendicular to the movement of the plates.
But not so with the geological fracture known as the Great Rift Valley, located in East Africa and running a whopping 6,400 kilometers from north to south. Here the deformations run both perpendicular and parallel to the movement of the plate. Geologists explain that the deformations suggest that the plate is being pulled from multiple directions at once, which does not occur in any other region of the planet’s lithosphere.
3D models developed by a team of geologists from Virginia Tech’s Department of Geosciences point to the parallel deformations in the world’s largest continental rift as the result of the African Superplume. The latter is a massive upwelling of hot mantle that emerges from deep within our planet, transporting heat to the surface.
The partially molten rock extends from the southwest and into the northeast of the African continent, becoming shallower along the way, and is what is giving flow to the mantle below. It is precisely such flow that appears to be “causing the anomalous northward deformation parallel to the rift” in the Great Rift Valley, says geophysicist Tahiry A. Rajaonarison, lead author of the research.
Africa Is Splitting in Half
The same African Superfeather is also causing a phenomenon known as seismic anisotropy, which occurs when rocks align in a certain direction in response to geologic forces in the mantle. Seismic anisotropy has been occurring beneath the Rift Valley geological fault, without experts being able to explain the phenomenon.
The same authors had come to a startling conclusion in an earlier study. Analyzing the combination of forces that could be acting on the rift, they saw how shallower lithospheric buoyancy forces as well as deeper mantle tensile forces. They concluded that both influence the deformation of the African fault.
“We confirm previous ideas that lithospheric buoyancy forces are driving the rift, but we are providing a new perspective that anomalous deformation may occur in East Africa,” Rajaonarison says.
The Great Rift Valley is the world’s largest continental geological fault, so large that it is believed that within millions of years, it will eventually split the African continent in half. The researchers believe their findings may help to understand how continental rifts that have already occurred billions of years in the past come about.
Story written in Spanish by Alejandra Martínez in Ecoosfera
