Africa to split into two and drift away

By Anton Yevseev

Australian scientists stated that Africa may split into two in the future. The scientists explored the Rukwa rift (the border between two lithospheric plates) in Tanzania and realized that the tectonic activity in the region was still high. Interestingly enough, all the processes that take place in the region bear a striking resemblance to the start of the split of the continent.

Africa did not exist as a continent 180 million years ago. Africa used to be a part of Gondwana supercontinent together with South America, Australia, the Antarctic, Hindustan, Arabia, Madagascar and New Zealand. In some 30 million years, the supercontinent split and broke into two parts. One of them included Africa and South America, whereas the other one included all the rest. 

Afterwards, all other parts of Gondwana separated from each other.

The continents went quiet afterwards, and it seems that none of them is going to split again. Africa can be an exception from this trend, though. Scientists discovered a long time ago that the eastern rift valley in Africa was a zone of a potential split. The tectonic activity in the region is still higher than anywhere else. In addition, the region is the place, where different lithospheric plates meet.

A group of scientists from James Cook University and Ohio University decided to study the processes that take place in the region. The scientists paid attention to the Rukwa rift in Tanzania. There are no active volcanoes there, which makes the work easier, because the observed phenomena do not depend on the volcanic activity.

The researchers said that one may learn a lot about tectonic processes from changes in riverbeds. Rivers react sharply to such phenomena as mountain formation, crustal recoil and so on. The scientists started studying the flood-plain of the Congo River. At first, they analyzed the tracks of geomagnetic inversions (the changes in the directions of the magnetic field of the Earth) in river sediments. Afterwards, they established the age of the volcanic ash that covered the ancient banks of the Congo River.

Afterwards, they analyzed the depositions of the ancient river plain. Since rivers erode the rocks from different geological eras, it would be logic to presume the following. If the riverbed changes, the structure and composition of the rocks that stood in the way of the water change too. The analysis therefore gives a picture of the path of the riverbed in ancient times.

As a result, the scientists discovered that the Congo River was flowing to the north-west during the Cretaceous period. The river was carrying the rocks from the geological provinces of the south-east. In Oligocene (34-23 million years ago), the river changed its course abruptly and started flowing in the south-eastern direction. Such things usually happen during the mountain formation period.

However, the Congo currently flows to the north-west again. The last time, when the river changed its course, took place approximately 25 million years ago. The crust on the rift went up again, although it happened on the other side of the rift.

Crustal recoils take place prior to the beginning of splits. The split itself occurs when the Earth's mantle pushes substances out, and they come to the surface at the places where the crust is thinner. The upper layers of the crust form "wrinkles" - the mountains that is.

However, the newly formed wrinkles create an obstacle for the substances coming out from the mantle. To put it otherwise, mountains play the role or a cork in a bottle of champagne. The pressure underneath them grows, the crust burst at some moment, and the substance from the mantle comes out to the surface, pushing the plates aside. The rift breaks, and if the process takes place on land, then it creates two continents from one.

One may observe the initial stage of this process in modern-day Africa. The substance underneath the continent is looking for a place to come out on the surface, causing the crust to go up. The rift does not break because Africa, that used to be the very center of Gondwana, consists of super thick plates. However, nothing lasts forever, and there will be the time when the plates burst.

It is worthy of note that Eurasia starts to "crawl" underneath the African plates. This may exacerbate the situation. When the pressure in the crust reaches a critical point, the Black Continent will split on the line of the Rukwa rift. The waters of the Indian Ocean will rush into the crack, and the process will end with the creation of two Africas - the smaller (North-Western) and the bigger one (South-Eastern).

The fate of the two new parts of the continent will most likely be different too. The north-western piece will be drifting towards South America.  The south-western part will have a choice. It may move either towards Australia or the Antarctic.