Study Detects Mantle-Derived Helium in Zambian Hot Springs, Supporting Suspected Kafue Rift Activity

A new study published Monday in the journal Frontiers in Earth Science reports that gas samples from hot springs and geothermal wells in Zambia contain elevated levels of helium-3, indicating that fluids from Earth's mantle are rising through the suspected Kafue Rift.

The study was led by Rūta Karolytė when she was a postdoctoral research fellow at the University of Oxford. Karolytė is currently a principal product scientist at UK-based Snowfox Discovery.

Researchers collected samples from six sites in a highly concentrated area along the suspected rift. They also sampled two hot springs located about 60 miles (95 kilometers) from the suspected rift. The team measured the ratio between helium-3 and helium-4 in the gas samples.

The samples from the rift area showed more helium-3 than normally found in the crust, indicating mantle fluids. No similar increase in the helium-3 ratio was found in the two hot springs 60 miles (95 kilometers) from the rift. 3 per cent were found in the fluids reaching the surface in the Kafue Rift.

1799564. “We have the first geochemical data from this area. That’s quite a different line of evidence that really strengthens the idea that we have rift activity in the area,” Rūta Karolytė stated.

“There’s hot water bubbling up to the surface, and we sampled the gas that’s coming up from that,” she added. “We found more helium-3 than you’d normally find in the crust, which is generally a signal of mantle fluids coming up into the water,” Karolytė stated. “What our data confirms is that this system is currently ‘awake’ and geologically active,” she said.