Magma Activity Under Africa Signals Formation of New Ocean

Deep beneath the Afar region of Ethiopia, a significant geological phenomenon is occurring as a plume of molten rock is gradually splitting the African continent, paving the way for a potential new ocean. Recent research published in the journal Nature Geoscience details how this process is unfolding.

This upward flow of hot material from the Earth's mantle is influenced by the tectonic plates above, which are the large, rigid pieces of the Earth's crust. Over millions of years, these plates are being pulled apart, becoming thinner, and ultimately fracturing. This fracture marks the genesis of a new ocean basin.

In the East African Afar region, situated primarily over 100 meters below sea level, three active rift zones converge: the Red Sea Rift, the Gulf of Aden Rift, and the East African Rift. A study team led by researchers from the University of Southampton discovered that magma from the mantle rises in rhythmic pulses, which are affected by the thickness of the tectonic plates and their rates of drift.

The Red Sea was formed from a rift where the African and Arabian plates are pulling apart. This rift extends northward through the Dead Sea and the Jordan Rift into Syria. Conversely, the East African Rift and its southern extension, the Central African Rift, traverse through the African Plate.

To gain insight into the subsurface activities, researchers analyzed over 130 rock samples from relatively young volcanoes in and around the Afar region. By combining these samples with previous geological analyses and statistical modeling, the research team evaluated the chemical composition of the rocks. They found that the mantle beneath Afar is neither uniform nor stationary; it exhibits pulsating behavior, with these pulses bearing distinct chemical signatures.

The Arabian and African plates are moving apart at approximately 15.5 millimeters per year in the Gulf of Aden, while the southern Red Sea rift sees a rate of about 14.5 millimeters per year. In the East African Rift, the drift speed south of Ethiopia's highlands is slower, at around 5.2 millimeters per year. The rift zones in the Afar region are lined with numerous volcanoes, which allow magma from the mantle to surface.

The researchers also investigated whether magma is rising from one central location or multiple points within the Afar region. Previous studies suggested that magma might be surfacing at several points near the Red Sea, the Abbe Lake region between Ethiopia and Djibouti, and southwest of Ethiopia's highlands. However, the latest simulations indicate that a singular mantle plume may exist beneath Abbe Lake, branching out beneath the surface along the three rift zones.