A new study of the famous iron-red rocks in Western Australia’s arid Pilbara region has revealed that the formation of Earth’s first continents occurred in a different way than originally thought.
The research, published in the journal Nature, sought to understand how the granite that made up the Earth’s earliest continents at the end of the Archaean eon (some 2.5 billion years ago) was formed. Critically, the researchers wanted to find where the water required for the granite’s formation came from.
To understand what Earth’s early history may have been like, the researchers tested the variation of oxygen isotope composition of zircon and compared this with the geochemistry of the rocks from Pilbara.
They found that the water in the type of granite present could not have come from the sky.
The study proposes that rather than coming from above, the water came from hydrated near-surface basalt rocks that were circulated into the Earth’s mantle through the process of overturn of the crust.
If this is correct, it means that rock formation processes in Earth’s early history were incredibly different from today.
Under these strange conditions, this mantle water may have been instrumental in forming the continents during Earth’s early years.
Read science facts, not fiction...
There’s never been a more important time to explain the facts, cherish evidence-based knowledge and to showcase the latest scientific, technological and engineering breakthroughs. Cosmos is published by The Royal Institution of Australia, a charity dedicated to connecting people with the world of science. Financial contributions, however big or small, help us provide access to trusted science information at a time when the world needs it most. Please support us by making a donation or purchasing a subscription today.