Ancient groundwater: discovered in a mine in South Africa

Scientists recently discovered the existence of groundwater 1.2 billion years ago in the depths of one mine in South Africa. Exactly a gold and uranium mine 2.9 km below the earth’s surface in Moab Khotsong. This discovery is good for a better understanding of life under the Earth’s surface and on other planets.

Alpha, beta and gamma rays are produced when uranium, thorium and potassium decay underground to cause radiogenic reactions in nearby rocks and fluids. The discovery was possible given the large amounts of radiogenic helium, neon, argon, xenon and an isotope of krypton, the latter never seen before. In practice thanks to the radiolysis that splits water molecules and creates vital hydrogen for Earth’s microbes deep within.

Solid materials such as plastic, stainless steel and even solid rock are eventually penetrated by diffusing helium, much like the deflation of a helium-filled balloon. Our results show that by diffusion, 75-82% of the helium and neon originally produced by the radiogenic reactions could be transported through the overlying crust. The study’s new insights into how much helium is spreading from the deep Earth is a critical step forward as global helium reserves become depleted and the transition to more sustainable resources gains momentum. Humans are not the only life forms that depend on the energy resources of the Earth’s deep underground. Since radiogenic reactions produce both helium and hydrogen, we can learn about helium reservoirs and transport and calculate the energy flow of hydrogen from the deep Earth. These calculations are vital to understanding how life is maintained underground on Earth and what energy may be available from radiogenic energy on other planets and moons in the solar system and beyond.

Oliver Warr, researcher at the University of Toronto