Fresh geochemical evidence from Zambia points to deep tectonic activity
Researchers studying hot springs in Zambia say they may have found some of the clearest evidence yet that a new tectonic plate boundary could be beginning to form in southern Africa. The key clue is chemical: gases emerging from the springs appear to include helium and carbon isotope signatures associated with Earth’s mantle rather than only the crust above it.
According to the supplied source text, the work focuses on the Kafue Rift, part of a 2,500-kilometer rift zone stretching from Tanzania to Namibia and possibly out into the Atlantic. Geologists had already suspected that the region might be in the early stages of continental rupture because of its geography, elevated subsurface temperatures, low-level seismicity and gravity anomalies. What was missing, the report says, was geochemical confirmation.
What the researchers found
Rūta Karolytė of the University of Oxford and colleagues analyzed gases from five hot springs and three geothermal wells in central Zambia. They found helium and carbon isotope ratios consistent with material originating from deep below the crust, suggesting that fluids from the mantle, from depths of up to 190 kilometers, are making their way toward the surface.
That matters because it points to a structural pathway through the overlying rock. In practical terms, the researchers interpret the result as evidence of a tear in the region’s tectonic plates. Karolytė told New Scientist that the data confirm the system is “awake” and geologically active.
