CONTINENTS ‘PRONE TO DESTRUCTION’ IN INFANCY

Geologists model the origin of the cratonic mantle. In a paper published in the journal Nature, a team led by Fabio Capitanio from Monash University has helped explain why no trace remains of the continents formed in the first 500 million years of Earth’s history.

Their mathematical simulations show that the release of internal primordial heat from the planet’s formation – which would have been three or four times greater than the amount released now – caused the upper part of the Earth’s mantle to melt. This oozed up to the surface as magma, or molten rock, to form new crust. The parts of the mantle left below were depleted and went on to form rigid “rafts” or “keels” that shielded the crust above – thus creating the start of continents we see today.

“Our results explain that continents remained weak and prone to destruction in their infancy, about 4.5 to 4 billion years ago, then progressively differentiated and became rigid over the next billion years to form the core of our modern continents,” Capitanio says.