New study refutes leading theory of continent formation
In the new study, Dr. David Hernández Uribe of the University of Illinois at Chicago used computer models to study the formation of magmas that are thought to hold clues to the origin of Earth's continents
Magma is a molten substance that, upon cooling, forms rocks and minerals. Dr. Hernández Uribe has sought magmas that match the compositional signature of rare mineral deposits called zircons, dating back to the Archean eon (from 2.5 to 4 billion years ago), a time when scientists believed the first continents were formed. In a recent study (https://www.nature.com/articles/s41561-024-01489-z), researchers argued that Archean zircons could only form through subduction, i.e., when two tectonic plates collide underwater, pushing the landmass to the surface. This process still occurs today, causing earthquakes and volcanic eruptions and reshaping the coastlines of continents. However, Dr. Hernández Uribe discovered that subduction was not necessary to create Archean zircons. Instead, he found that the minerals could form through the high pressure and temperatures associated with the melting of Earth's thick primordial crust.
In addition:
"Using my calculations and models, it is possible to achieve the same signatures for the zircons and even provide a better match through partial melting of the bottom of the crust,"
stated Dr. Hernández Uribe.
"Therefore, based on these results, we still do not have sufficient evidence to determine which process formed the continents."
The findings also raise uncertainties about the time when plate tectonics began on Earth. If the Earth's first continents were formed by subduction, this means they began to move between 3.6 and 4 billion years ago, just 500 million years after the planet's formation. However, the alternative theory that the melting of the crust gave rise to the first continents implies that subduction and tectonics might have started much later.
"Our planet is the only one in the solar system to have active plate tectonics as we know it,"
Dr. Hernández Uribe stated.
"And this is related to the origin of life, because the way the first continents moved controlled the climate, controlled the chemistry of the oceans, and everything related to life."
