New tectonic plate boundary could be forming in Zambia, scientists say

Scientists believe a new continental rift might be forming in Zambia. This idea comes from analyzing gas from geothermal springs. High levels of helium isotopes suggest a weak spot in Earth's crust has reached the mantle below.

This rift could eventually become a new boundary between tectonic plates. It also offers chances for geothermal energy, which could help local economies.

Professor Mike Daly from the University of Oxford explained that hot springs in Zambia's Kafue rift show helium isotope signs. These signs mean the springs connect directly to Earth's mantle, about 40 to 160 kilometers deep.

This connection shows the Kafue Rift's fault boundary is active. It suggests the Southwest African Rift Zone is also active. This could be an early sign that sub-Saharan Africa is starting to break apart.

Uncovering the Rift

The Kafue Rift is part of a 2,500-kilometer-long rift system. This system stretches from Tanzania to Namibia and might even reach the mid-Atlantic ridge. Scientists noticed the area because of its landscape, which hinted at a new rift. They also saw many geothermal spots and hot springs.

To confirm a new rift, scientists needed to prove it had broken through Earth's crust. This would mean fluids from the liquid mantle were escaping to the surface.

Daly described a rift as a big break in Earth's crust. It causes the ground to sink and other areas to rise. A rift can become a plate boundary, but often it stops before the crust fully breaks and a new plate boundary forms.

Scientists visited eight geothermal wells and springs in Zambia. Six were in the suspected rift zone, and two were outside it. They collected gas samples from bubbling water and analyzed the isotopes of each element.

Isotopes are different forms of an element. They are found in different amounts in the crust and the mantle. By checking the isotopes in the gas, scientists could tell if mantle fluids were reaching the surface. They compared these findings to samples from the East African Rift System, an older, well-known rift.

Earth's Shifting Surface

The scientists found that gas from the Kafue Rift had helium isotope ratios similar to samples from the East African Rift System. This was not true for the springs outside the rift.

The helium could not have come from the atmosphere because the isotope ratios were different. It also couldn't have come only from the crust, as there was too much mantle-sourced helium.

Kafue Rift samples also had carbon dioxide levels consistent with mantle fluids. Helium isotopes signal early-stage rifting. Scientists predict that carbon dioxide will become more common as volcanic centers grow, based on the East African Rift System.

The discovery that the Kafue Rift is active has important economic potential. Early-stage rifts can provide geothermal energy. They also offer access to helium and hydrogen, which are not mixed with volcanic gases. However, this discovery could also greatly impact Africa's future shape.

Daly noted that many features of Kenya's Great Rift Valley suggest East Africa should eventually become a major continental break-up line.

But the East African Rift System is rifting slowly. Mid-ocean ridges on almost all sides of Africa tend to stop east-west or north-south expansion. This makes it hard for a break-up and spreading to start.

The Southwestern African Rift System could be an alternative. It has the right rift features. Its crust has natural weaknesses that line up well with the surrounding mid-ocean ridges and landforms. This might make it much easier for continental break-up to happen there.

Daly cautioned that this study is based on helium analysis from only one area in the Southwestern African Rift System, which is thousands of kilometers long. More extensive studies are planned, with the next step happening this year.

Deep Dive & References

The Southwestern Rift of Africa: isotopic evidence of early-stage continental rifting - Frontiers in Earth Science, 2026