STELLENBOSCH, South Africa, Aug. 2 (UPI) -- South African geologists say they've found evidence of the existence of active plate tectonics during the Archaean era, when life on Earth originated.
The research by Jean Francois Moyen and colleagues at the University of Stellenbosch supports the idea that tectonic processes were occurring more than 2,500 million years ago -- much earlier than thought.
The geologists studied a suite of metamorphic rocks found in South Africa's Barberton region. They discovered the mineral assemblages present in the rocks point to the existence of high-pressure, low-temperature metamorphism, which is characteristic of subduction zones.
Subduction is a central part of plate tectonics in which cold, dense, oceanic crust sinks into the Earth. Until now, the presence of tectonic processes in the Archaean era has been disputed due to the lack of such evidence for subduction in the rock record.
The research is detailed in the current issue of the journal Nature.
