In the new study, Dr David Hernández Uribe from the University of Illinois at Chicago used computer models to study the formation of magma, which is thought to hold clues to the origin of Earth's continents.
Hadean Earth. Image by Alec Brenner.
Magma is molten material that forms rocks and minerals as it cools.
Dr Hernández Uribe searched for magma that matched the compositional characteristics of rare mineral deposits called zircons, which date back to the Archean Era (2.5 to 4 billion years ago), when scientists believe the continents first formed.
In a recent study, researchers argued that Archean zircons could only have been formed by subduction, i.e. two crustal plates colliding under the ocean and pushing land up onto the surface.
This process still occurs today, causing earthquakes and volcanic eruptions and reshaping the coastlines of continents.
However, Dr. Hernández Uribe found that subduction was not necessary for the formation of Archean zircons.
Rather, he found that the minerals may have formed due to the high pressures and temperatures associated with the melting of Earth's thick primordial crust.
“Using my calculations and models, we can get the same characteristics in zircons and even a better match through partial melting at the base of the crust,” Dr Hernández Uribe said.
“So based on these results, we don't yet have enough evidence to say by what process the continents formed.”
The findings also create uncertainty about when plate tectonics began on Earth.
If Earth's first continents formed by subduction, then the continents would have started moving between 3.6 and 4 billion years ago, or just 500 million years after Earth existed.
But an alternative theory, that the first continents formed from melting crust, means that subduction and tectonic shifts may have started much later.
“As far as we know, Earth is the only planet in the solar system where plate tectonics is actively occurring,” Dr Hernández Uribe said.
“And this has implications for the origin of life, because how the first continents moved controlled the weather, controlled the chemistry of the oceans, and controlled everything related to life.”
of study Published in the journal on July 11, 2024 Nature Chemistry.
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Hernández-Uribe, D. Generation of Archean oxidized and wet magmas by mafic crustal overthickening. National GeographyPublished online July 11, 2024; doi: 10.1038/s41561-024-01489-z
This article is a version of a press release from the University of Illinois at Chicago.
Source: www.sci.news
