The cratons, planet Earth’s first continents, arose from the seas between 3.3 and 3.2 billion years ago, a new study has suggested – several hundred million years before what was previously believed.
New research has shown that subaerial conditions occurred in the entire Singhbhum Craton, eastern India. The researchers examined rocks for tiny crystals – zircons – which contain uranium in order to date them.
The team arrived at the conclusion, after calculating the decomposition of the uranium. “over 700 million years earlier than most models predict.”
The paper was published Monday by Proceedings of the National Academy of Sciences. “when and how Earth’s earliest continents — the cratons — first emerged above the oceans (i.e., emersion) remains uncertain.”
The scientists stressed that it is crucial to understand the chronology and first formation of continental crust. “as it likely played a critical role in establishing Earth’s habitability.”
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Researchers analyzed igneous as well as sedimentary rocks from the craton. The lead author of the research, Dr Priyadarshi Chowdhury of Monash University, remarked that the rocks must have formed on land because of features like ripple markings – similar to the patterns wind and waves leave on sandy beaches.
After creating a model to mimic the conditions which formed the rocks and propelled them out of the ocean, the team hinted that hot magma beneath the Earth’s crust caused parts of the craton to thicken. Lightweight materials like sicilia, quartz and quartz made the matter buoyant, lifting it from the ocean.
“There was no uncertainty that continents were partly sticking out of water as early as 3.4 billion years ago,”Live Science was told by Ilya Bindeman (a professor of geology at the University of Oregon).
Similar geographic incidences were also observed in Australia and South Africa cratons. This suggests that several landmasses may have existed on Earth during this time, according to scientists.
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