Geologists Shed Recent Light On How Continents May Have Been Formed
An international research group has discovered that the 1st continents were not stable and also were recycled inside the Earth, in the mantle.
The research, released today in the Proceedings of the National Academy of Sciences (PNAS), is significant because it provides essential clues on how planets formed.
“The rocks in the core of the continents, referred to as cratons, are more than 3 billion years old,” describes lead study author Associate Professor Fabio Capitanio from the Monash College School of Earth, Atmosphere, and Environment.
” They formed in the early Earth and held the secret to how continents and the planet changed over time.”
The researchers used high-performance computational modeling to simulate the evolution of the Earth’s 1st billion years.
They discovered that the first continents were unstable and also recycled in the Earth’s mantle.
Once the early continental blocks were in the mantle, they were melted down, stirred, and blended until they were gone.
What researchers found on the continents?
The researchers discovered that some pieces of the original rocks could stay in the mantle for billions of yrs, but eventually, they come back up.
” Our work is important in 2 ways,” said Associate Professor Capitanio.
First, cratons are where essential metals and other minerals are stored/found.
“And second, they inform us how the planets formed and modified in the past, including how the continents came to be and also how they supported life, and how the atmosphere developed and changed as an outcome of the planets’ tectonics.”
Over time, the recycled pieces of the continent can build up under the new lithosphere, making it more buoyant and robust enough to stop more recycling.
The study is unique because it describes how continents are put together.
Many observations of old continental cores, known as cratons, show that they are much more complex and heterogeneous than the lithosphere of today. However, researchers did not know what caused the differences or how they developed.
The study reveals that parts of the cratonic lithospheric mantle (CLM) still exist in the mantle as diffused, exhausted heterogeneities at multiple scales that could last for billions of years.
Relamination functions best at high levels of depletion and mantle temperatures that are equal to those of the early Soil. This leads to the upwelling and underplating of big quantities of foundered CLM, which is called massive regional relamination (MRR).
MRR describes the complex source, age, and depletion heterogeneities found in ancient CLM. This suggests that this may have been an essential part of building continents in the early Earth.
More information:
Accretion of the cratonic mantle lithosphere via massive regional relamination, Proceedings of the National Academy of Sciences (2022). doi.org/10.1073/pnas.2201226119
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