Unusual helium signatures detected in Zambian hot springs may signal that a hidden tectonic rift is actively developing beneath southwestern Africa.
Deep beneath Zambia, scientists may have uncovered signs that Africa is slowly tearing apart. Clues rising from bubbling geothermal springs suggest that molten material from Earth’s mantle is pushing upward through a hidden fracture in the crust, a process that could mark the birth of a new continental rift.
The discovery comes from an analysis of gases released by hot springs in Zambia’s Kafue Rift. Researchers detected unusually high levels of mantle-derived helium isotopes, a chemical fingerprint that points to a direct connection between the surface and Earth’s deep interior. Over millions of years, rifts like this can grow into tectonic plate boundaries capable of reshaping continents and even creating new oceans.
At the same time, the geological activity could bring more immediate benefits. Rift systems are often linked to geothermal energy resources and underground reserves of gases such as helium and hydrogen, both of which are increasingly valuable for modern technology and energy systems.
“The hot springs along the Kafue rift of Zambia have helium isotope signatures which indicate that the springs have a direct connection with the Earth’s mantle, which lies between 40 and 160km below the Earth’s surface,” said Prof Mike Daly of the University of Oxford, an author of the article in Frontiers in Earth Science. “This fluid connection is evidence that the fault boundary of the Kafue Rift is active and therefore the Southwest African Rift Zone is too — and may be an early indication of the break-up of sub-Saharan Africa.”
Evidence of a Hidden Rift
The Kafue Rift is part of a 2,500km (1,553-mile) rift system stretching from Tanzania to Namibia, with a possible connection to the Mid-Atlantic Ridge. Researchers became interested in the area because of its unusual landscape, geothermal activity, and numerous hot springs, all signs that can point to an emerging rift system.
To confirm that a new rift was forming, scientists needed proof that material from deep within Earth had reached the surface. Specifically, they looked for chemical evidence that fluids from the mantle had moved upward through the crust.
“A rift is a large break in the Earth’s crust that creates subsidence and associated elastic uplift,” said Daly. “A rift may become a plate boundary, but commonly a rift’s activity ceases before the point of lithospheric break-up and plate boundary formation.”
Researchers collected gas samples from eight geothermal wells and springs across Zambia, including six within the suspected rift zone and two outside it. The gases bubbling up through the water were analyzed in the lab to measure their isotopes, which are different forms of the same element.
Because isotopes occur in different proportions in Earth’s crust and mantle, scientists can use them to trace where gases originated. The team also compared the Zambian samples with data from the East African Rift System, a much older and well-established rift.
Mantle Signals Beneath Zambia
The results showed that gas from the Kafue Rift contained helium isotope ratios similar to those found in the East African Rift System. Springs located outside the rift zone did not show the same pattern.
Researchers ruled out the atmosphere as the source because the isotope ratios did not match those found in air. The crust alone also could not explain the findings, since the samples contained too much mantle-derived helium.
The Kafue Rift gases also included carbon dioxide levels consistent with mantle fluids. Scientists say helium isotopes are a useful marker of early-stage rifting. Based on the evolution of the East African Rift System, they expect carbon dioxide emissions to become more prominent over time as volcanic activity develops.
Implications for Africa’s Future
Scientists say the discovery could have important economic benefits. Early-stage rift systems may provide access to geothermal energy as well as underground helium and hydrogen resources that are less diluted by volcanic gases.
The findings could also influence scientists’ understanding of how Africa may eventually split apart.
“Many of the features of the Great Rift Valley of Kenya offer compelling reasons why East Africa should ultimately become a line of major continental break-up,” said Daly. “But the rate of rifting of the East African Rift System is slow. On almost all sides of Africa there are mid-ocean ridges tending to inhibit east-west or north-south extension, so break-up and spreading does seem to struggle to establish itself. The Southwestern African Rift System could be an alternative. It has the required rift-related features, and regional basement fabrics — inherent weaknesses in the crust — favorably aligned to the surrounding mid-ocean ridges and continental geomorphology. This relationship may offer a much lower strength threshold for continental break-up.”
“However, this study is based on helium analyses from one general area in the Southwest African Rift System, which is thousands of kilometers long,” cautioned Daly. “This early study is being followed by more extensive studies, the next step of which will be completed this year.”
Reference: “The Southwestern Rift of Africa: isotopic evidence of early-stage continental rifting” by Rūta Karolytė, Michael C. Daly, Peter Vivian-Neal, Darren Hillegonds, Long Li, Barbara Sherwood Lollar and Chris J. Ballentine, 16 March 2026, Frontiers in Earth Science.
DOI: 10.3389/feart.2026.1799564
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