Southern Africa’s Hidden Rift

Geologists have long known that the eastern arm of Africa is gradually pulling away from the rest of the continent. Recent research from the University of Oxford now adds a new, massive fracture in the south‑west, suggesting that the continent could eventually break apart into three distinct blocks rather than two.

The Kafue Rift Discovery

The team focused on the Kafue Rift in Zambia, a narrow zone where the lithosphere is being stretched and the surface has subsided. By analysing eight gas samples—six from hot springs and drilling sites inside the rift and two from distant reference locations—the scientists were able to trace the origin of the gases to deep mantle sources.

Helium as a Geological Fingerprint

Helium exists in two isotopic forms: helium‑3, which mainly originates from the mantle, and helium‑4, produced by radioactive decay in the crust. The ratio of these isotopes acts like a fingerprint. Inside the Kafue Rift the helium‑3 to helium‑4 ratio was eight times higher than expected for crust‑derived gas, unequivocally pointing to mantle contributions. The control sites showed only the typical crustal signature. One sample even contained carbon dioxide that appeared to be mantle‑derived, reinforcing the conclusion that deep‑seated material is rising through the fracture.

From Two Plates to Three?

Scientists already recognize the East African Rift—a 6,000‑kilometre‑long fault that will eventually separate East Africa from the rest of the continent. The newly documented southern fracture is far earlier in its evolutionary stage, making it harder to detect visually. However, the mantle gas signals provide compelling evidence that a larger, roughly 2,500‑kilometre‑long fault system extends from Tanzania down to Namibia.

This secondary fault gives rise to the concept of a “San Plate,” a block that could detach from the main African Plate along with the well‑known Nubian Plate in the east. If both processes continue over millions of years, Africa may end up as three independent tectonic entities.

Economic and Strategic Implications

Beyond the academic intrigue, the findings have practical relevance. Mantle‑derived gases that seep through rift zones are often accompanied by low seismic activity and groundwater that can trap carbon dioxide. Such conditions are favorable for the exploration of valuable resources like helium, a critical element for MRI machines, scientific instruments and aerospace applications. As geopolitical tensions threaten traditional helium supplies, new domestic sources could become strategically important.

The study also hints at the possibility of locating “white hydrogen” – naturally occurring hydrogen released from the Earth’s interior. Unlike gray hydrogen (produced from fossil fuels) or green hydrogen (generated with renewable electricity), white hydrogen is emitted directly from geological processes and could offer a cleaner energy carrier if extracted at scale.

Future Work and Outlook

To confirm the preliminary results, additional sampling along the presumed fault line in Botswana, Namibia and surrounding regions is essential. Detecting similar mantle gas signatures elsewhere would strengthen the case for a continent‑wide rift system.

For now, residents of Lusaka, Windhoek and other southern cities can rest easy; the tectonic re‑configuration will unfold over tens of millions of years. Nonetheless, the research opens exciting avenues for both scientific discovery and the pursuit of scarce commodities.

Source: https://scientias.nl/afrika-scheurt-misschien-niet-in-twee-maar-in-drie/