North American continent slowly losing rock from its underside, discover scientists
Researchers have discovered that the North American continent is slowly losing rock from its underside in a process called "cratonic dripping."
This is caused by the remnants of the Farallon Plate, an ancient tectonic plate, which is influencing the mantle and causing blobs of rock to detach and sink.
The Midwest of the United States is where the dripping effect is most intense.
But don't worry, the continent isn't about to collapse. These are incredibly slow geological processes, happening over millions of years.
It provides valuable insights into how continents evolve over millions of years.
The team at the University of Texas at Austin examined cratons, the ancient rock formations that make up Earth's continents.
"We made the observation that there could be something beneath the craton. Luckily, we also got the new idea about what drives this thinning," said Junlin Hua, the study's lead author.
Cratons are ancient, stable parts of continents that can last billions of years. However, they are not immune to change, and can experience alterations that disrupt their stability or lead to the loss of rock layers.
One past example of craton change is the North China Craton, but the current discovery of cratonic dripping in North America is significant because it's presently happening.
The researchers predict the dripping will halt once the tectonic plate remnants sink deeper, thus diminishing their impact on the craton.
"This sort of thing is important if we want to understand how a planet has evolved over a long time. It helps us understand how do you make continents, how do you break them, and how do you recycle them [into Earth]," said Thorsten Becker, co-author, in the press release.
So, what's causing this slow, subterranean drip? The remnants of the Farallon Plate.
Researchers used advanced seismic imaging and computer models to see and simulate this process. The models showed that the dripping stopped when the Farallon Plate was removed, confirming its role.
This project generated a detailed computer model of North America's subsurface utilizing EarthScope seismic data. It ultimately revealed previously unseen geological processes within the continent's crust and mantle.
The new computer model allowed scientists to visualize the "dripping" phenomenon for the first time.
Furthermore, it provided evidence linking the dripping to the Farallon Plate, an ancient oceanic plate that has been subducting under North America for last 200 millions of years.
Researchers found the model's output closely aligned with observed data, suggesting its accuracy.
"You look at a model and say, "Is it real, are we overinterpreting the data or is it telling us something new about Earth? But it does look like in many places that these blobs come and go, that it's [showing us] a real thing," added Becker.
This discovery is essential for unraveling the mysteries of Earth's dynamic systems, particularly the formation and transformation of continents across immense timescales.
The findings were published in the journal Nature Geoscience.
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