Plate tectonics is the geological process that shapes the Earth's surface, creating mountains and driving the movement of the continents. It is thought that plate tectonics may have emerged from an earlier regime called stagnant lid convection.
In stagnant lid convection, the Earth's solid outer shell, called the lithosphere, is too thick to move or break up. As the Earth's interior heats up, heat is transferred from the planet's core to its surface through conduction.
"We believe the transition between stagnant lid convection and plate tectonics is a fundamental and important problem in understanding how the modern Earth formed," said Dr. Simon Labrosse from the ANU Research School of Earth Sciences.
"Stagnant lid convection has a different effect on the planet's heat dissipation compared to plate tectonics. And so by calculating how efficiently heat is lost in each regime, we can use this as a way to test whether plate tectonics has actually occurred."
Using a high-performance computer, the researchers ran thousands of simulations of convection with different temperatures, thicknesses of the lithosphere and other factors. They found one scenario that resulted in a transition from stagnant lid convection to plate tectonics when the temperature at the base of the lithosphere reached a critical value.
"This means the Earth's plate tectonics could be switched on and off, driven by changes in mantle temperature and the thickness of the lithosphere," said Dr. Labrosse.
"This is the first time we have been able to show how plate tectonics can be triggered by convection, but more work is needed to fully understand this transition and its implications for the evolution of the Earth."
The team's findings are published in the journal `Geophysical Research Letters.`
