The University of Southampton, in collaboration with several other institutions, has conducted a study revealing significant findings about the Earth's mantle beneath the Afar region in Ethiopia. The research, published in Nature Geoscience, indicates that a plume of hot mantle material pulses upward beneath this area, contributing to the gradual separation of the African continent and the formation of a new ocean.
Dr. Emma Watts, who led the research while at the University of Southampton and is now based at Swansea University, explained: “We found that the mantle beneath Afar is not uniform or stationary – it pulses, and these pulses carry distinct chemical signatures. 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.”
The project brought together experts from ten institutions including Swansea University, Lancaster University, Universities of Florence and Pisa, GEOMAR in Germany, Dublin Institute for Advanced Studies, Addis Ababa University, and GFZ German Research Centre for Geosciences.
Afar is notable for being one of the few places on Earth where three tectonic rifts meet: the Main Ethiopian Rift, Red Sea Rift, and Gulf of Aden Rift. The presence of a hot upwelling mantle plume beneath this region has long been suspected to drive crustal extension and future ocean basin formation.
The research team collected over 130 volcanic rock samples from Afar and utilized existing data alongside advanced statistical modeling to examine crustal structure and mantle composition. Their findings revealed an asymmetric plume with distinct chemical bands resembling geological barcodes across the rift system.
Professor Tom Gernon from the University of Southampton noted: “The chemical striping suggests the plume is pulsing like a heartbeat. These pulses appear to behave differently depending on the thickness of the plate and how fast it’s pulling apart. In faster-spreading rifts like the Red Sea, the pulses travel more efficiently and regularly like a pulse through a narrow artery.”
This dynamic behavior contrasts with previous assumptions that such plumes were static. Dr. Derek Keir from both Southampton and Florence universities emphasized: “We have found that evolution of deep mantle upwellings is intimately tied to motion of plates above. This has profound implications for how we interpret surface volcanism, earthquake activity, and process of continental breakup.”
Keir added that further research will focus on understanding how mantle flow occurs beneath tectonic plates.