The first continents emerged on Earth more than three billion years ago, or more than 500 million years earlier than previously thought, strongly influencing the atmosphere, the oceans themselves, the climate and life on Earth.
It is the first time that a precise date has been identified for the origin of the cratons, as the first emerged lands are called.
The dating, published in the journal of the United States Academy of Sciences, Pnas, is due to the group of geologists Priyadarshi Chowdhury and Jacob Mulder, of the Australian Monash University.
The researchers analyzed data from the Singhbhum craton in India relating to igneous rocks and sediments, dated between 3.6 and 2.8 billion years ago. On this basis they obtained a model thanks to which they reconstructed both the times and the mechanism that led to the emergence of the first continents. The model indicates that the Singhbhum craton was formed between 3.3 and 3.2 billion years ago and is therefore older than previously believed, considering that previous estimates traced its origin to 2.5 billion years ago. .
As for the mechanism, according to the researchers, a progressive thickening of the magma and the rise of a silica-rich earth crust could have been driving the emergence of the first lands.
It is, they observe, a very different mechanism from the one that controls the movements of the continental plates today.
Finally, scholars believe that the emergence of the first continents may have contributed to the proliferation of life: changes in the atmosphere could have changed the planet's meteorology and climate, favoring the influx of nutrients into the oceans, as well as the rise of oxygen levels and glaciations that occurred in the Archean period, between 3.8 and 2.5 billion years ago.