Beneath the cracked surface of northeastern Africa, molten rock pulses upward like a beating heart, slowly prying the continent apart and heralding the birth of a new ocean basin. Earth scientists have uncovered rhythmic surges of hot mantle rising beneath the Afar region in Ethiopia, where three tectonic rifts converge. Over millions of years, these pulses stretch and thin the overlying crust—almost like soft plasticine—until it ruptures, marking the first breaths of a nascent ocean.
The Afar triple junction—where the Main Ethiopian Rift, the Red Sea Rift and the Gulf of Aden Rift meet—is one of the few places on Earth offering a window into deep mantle dynamics. By collecting and analysing more than 130 volcanic rock samples from across the region and combining them with existing geochemical and geophysical data, the team revealed a single, asymmetric plume beneath Afar. This plume carries distinct chemical “barcodes” in bands that repeat across each rift arm, indicating that pulses of partially molten mantle are being channelled by the stretching plates above.
“We found that the mantle beneath Afar is not uniform or stationary – it pulses, and these pulses carry distinct chemical signatures,” says Dr Emma Watts of Swansea University. “These ascending pulses of partially molten mantle are channelled by the rifting plates above. That’s important for how we think about the interaction between Earth’s interior and its surface.”
These pulsations vary in spacing and strength depending on the rift’s extension rate and plate thickness. In faster-spreading sections like the Red Sea Rift, the pulses travel more efficiently—akin to blood flowing through a wide artery. Slower, narrower rifts bottleneck the upwelling, compressing the chemical heterogeneities into tighter bands.
Dr Derek Keir of the University of Southampton adds, “We have found that the evolution of deep mantle upwellings is intimately tied to the motion of the plates above. This has profound implications for how we interpret surface volcanism, earthquake activity, and the process of continental breakup.”
By teasing apart the chemical and physical choreography between plume and plate, this research not only illuminates the forces tearing Africa apart but also refines our understanding of how new oceans are born.
“Working with researchers with different expertise across institutions, as we did for this project, is essential to unravelling the processes that happen under Earth’s surface and relate it to recent volcanism,” Watts reflects. “Without using a variety of techniques, it is hard to see the full picture, like putting a puzzle together when you don’t have all the pieces.”
Dr Derek Keir of the University of Southampton adds, “We have found that the evolution of deep mantle upwellings is intimately tied to the motion of the plates above. This has profound implications for how we interpret surface volcanism, earthquake activity, and the process of continental breakup.”
By teasing apart the chemical and physical choreography between plume and plate, this research not only illuminates the forces tearing Africa apart but also refines our understanding of how new oceans are born.
“Working with researchers with different expertise across institutions, as we did for this project, is essential to unravelling the processes that happen under Earth’s surface and relate it to recent volcanism,” Watts reflects. “Without using a variety of techniques, it is hard to see the full picture, like putting a puzzle together when you don’t have all the pieces.”
The study has been published in Nature Geoscience.
