A network of deep‑underground neutrino detectors is giving scientists a fresh look at the radioactive elements that power Earth’s tectonic heat engine. While the JUNO experiment near Guangzhou, China, is poised to report its first geoneutrino detections this year, the SNO+ detector in Sudbury, Canada, has already captured its first signal, marking the first measurements in the western hemisphere.

Geoneutrinos are produced by the decay of uranium, thorium, and potassium in the mantle and crust. Their detection allows a direct count of the planet’s heat‑producing elements, which drive plate tectonics and the magnetic field. SNO+ sits beneath 2 kilometers of rock, shielding it from cosmic rays combustible to this delicate measurement.

Early results hint that the mantle may not be chemically uniform. Regions above the large low‑shear‑velocity provinces (LLSVPs) under Africa and the Pacific appear to generate more geoneutrinos, suggesting that deep Earth structures could concentrate certain radioactive elements. This challenges the long‑held assumption that mantle mixing has homogenized these materials.

Despite the excitement, uncertainties remain large, and scientists caution against over‑interpreting the data. Future detectors and refined analyses may eventually produce a chemical map of Earth’s interior and clarify the origins of the mantle’s mysterious structures.