Latest news with #JunlinHua
Yahoo
22-04-2025
- Science
- Yahoo
North America's underside is slowly melting into the Earth
As you read this, the North American continent's underside is dribbling away into Earth's molten mantle. And according to researchers at the University of Texas at Austin, this may be the first time anyone's analyzed this geological phenomenon called 'cratonic thinning' in real time. The team recently published their findings in the journal Nature Geoscience. Cratons are ancient, huge rock formations that compose portions of the planet's continents. Although they often maintain their stability for billions of years, geologic regions occasionally shift in ways that can cause entire layers of rock to disappear during a process known as cratonic thinning or cratonic dripping. One documented example occurred in the North China Craton's deepest root layer millions of years ago. However, until recently, scientists hadn't had a chance to study the process as it happened. But maybe not for long. During the development of a new, full-waveform seismic tomographic model of North America at UT Austin geoscientist Junlin Hua and colleagues noticed odd behavior at the border between Earth's deep mantle and its thinner lithosphere. 'We made the observation that there could be something beneath the craton,' Hua, a study co-author now a professor at China's University of Science and Technology, said in a statement. 'Luckily, we also got the new idea about what drives this thinning.' Their tomographic modeling suggests that an oceanic tectonic plate known as the Farallon Plate underneath a large portion of the Pacific Ocean may be to blame. First seismically imaged in the 1990s by study co-author Stephen Grand, the Farallon Plate has spent the last 200 million years subducting underneath North America. Although separated from the craton-in-question by about 370 miles, the Farallon Plate appears to be redirecting mantle material flow into a path that melts away the bottom of the craton. The resulting activity is potentially releasing volatile compounds t, which weaken the larger craton base. 'A very broad range is experiencing some thinning,' said Hua. To test this theory, Hua and colleagues ran their computer model with and without the inclusion of the Farallon Plate. When it was in the model, the craton removed, the dripping ceased altogether. 'You look at a model and say, 'Is it real, are we overinterpreting the data or is it telling us something new about the Earth?,'' said study co-author and planetary sciences professor Thorsten Becker. 'But it does look like in many places that these blobs come and go, that it's [showing us] a real thing.' Becker underscored the importance of such discoveries by explaining how they assist planetary scientists in better understanding Earth's evolutionary history. 'It helps us understand how do you make continents, how do you break them, and how do you recycle them [into the Earth,]' he said. The dripping appears to be focused primarily under the US Midwest, but that doesn't mean residents in places like Topeka or Cleveland don't need to worry. Processes like cratonic dripping influence tectonic activity over the course of millions of years. Not only that, but similar events generally stop once the Farallon Plate's remnants sink deeper into the mantle and cease affecting the North American craton.
Yahoo
07-04-2025
- Science
- Yahoo
Uh, Looks Like North America is ‘Dripping' Into Earth's Mantle
Cratons are the most ancient, stable pieces of tectonic plates, but even these geological formations can change over time. A new study details how the North American plate is 'dripping' into the mantle due to the continued influence of the Farallon Plate, which has been subducting under the continent for 200 million years. While this 'dripping' is located beneath the U.S., it doesn't hold any consequences for us surface-dwellers. But it does provide a unique opportunity for scientists to study the formation—and disintegration—of continents. While there's often much to-do about tectonic plates, especially when their various subductions and transform sliding creates widespread devastation, cratons rarely nab the limelight. That's not because they're not unimportant—after all, they form the geologic core of all tectonic plates around the world. But as a result of being the most ancient pieces of Earth's lithosphere (containing the crust and uppermost mantle), they aren't subjected to nearly as much geologic dynamism as is found throughout the rest any particular plate. They're just kind of… there. However, recent research has shown that even these geologic stalwarts face incredible change over time. A study by Chinese scientists in October of last year detailed how one of the oldest pieces of continental crust—the North China Craton (NCC)—had slowly been disintegrating in a process known as 'decratonization' over the course of 200 million years. At the time, the author noted that the North American craton could experience similar deformations. Now, a new study published in the journal Nature Geoscience shows the deformation currently impacting the North American craton. Primarily located under the Midwest in the U.S., this craton appears to be 'dripping' into the mantle due to a subducting oceanic slab known as the Farallon Plate, according to researchers at the University of Texas at Austin (UT). What's fascinating about the North American craton's 'dripping' process—as opposed to the decratonization of the NCC, for example—is that this process is happening as we speak, which gives scientists an unprecedented opportunity to learn more about the geology of these lithospheric cores. 'We made the observation that there could be something beneath the craton,' Junlin Hua, the lead author of the study who is now a professor at University of Science and Technology of China, said in a press statement. 'Luckily, we also got the new idea about what drives this thinning.' By creating a full-waveform tomographic model of the North American plate using seismic data gathered from the EarthScope project, Hua and his team were able to spot this 'dripping' behavior far beneath the Earth's surface. The main engine behind the dripping (shown in the image above) is the Farallon Plate—an oceanic plates that's been subducting under the North American Plate for 200 million years, and has played a starring role in shaping the continent. The researchers theorize that this plate is impacting the craton by redirecting mantle flow, while also releasing volatile compounds that wear away the base of the plate. Of course, this doesn't mean that the Midwest will suddenly sink into an abyss. In fact, the researchers estimate that this 'dripping' will eventually end as the Farallon Plate continues to sink into the mantle and its influence on the craton wanes. 'This sort of thing is important if we want to understand how a planet has evolved over a long time,' Thorsten Becker, a co-author of the study from UT, said in a press statement. 'It helps us understand how do you make continents, how do you break them, and how do you recycle them [into the Earth.]' Who says cratons can't be exciting? You Might Also Like The Do's and Don'ts of Using Painter's Tape The Best Portable BBQ Grills for Cooking Anywhere Can a Smart Watch Prolong Your Life?
Yahoo
06-04-2025
- Science
- Yahoo
North America is 'dripping' down into Earth's mantle, scientists discover
When you buy through links on our articles, Future and its syndication partners may earn a commission. An ancient slab of Earth's crust buried deep beneath the Midwest is sucking huge swatches of present-day's North American crust down into the mantle, researchers say. The slab's pull has created giant "drips" that hang from the underside of the continent down to about 400 miles (640 kilometers) deep inside the mantle, according to a new study. These drips are located beneath an area spanning from Michigan to Nebraska and Alabama, but their presence appears to be impacting the entire continent. The dripping area looks like a large funnel, with rocks from across North America being pulled toward it horizontally before getting sucked down. As a result, large parts of North America are losing material from the underside of their crust, the researchers said. "A very broad range is experiencing some thinning," study lead author Junlin Hua, a geoscientist who conducted the research during a postdoctoral fellowship at The University of Texas (UT) at Austin, said in a statement. "Luckily, we also got the new idea about what drives this thinning," said Hua, now a professor at the University of Science and Technology of China. The researchers found that the drips result from the downward dragging force of a chunk of oceanic crust that broke off from an ancient tectonic plate called the Farallon plate. The Farallon plate and the North American plate once formed a subduction zone along the continent's west coast, with the former sliding beneath the latter and recycling its material into the mantle. The Farallon plate splintered due to the advance of the Pacific plate roughly 20 million years ago, and remnant slabs subducted beneath the North American plate slowly drifted off. One of these slabs currently straddles the boundary between the mantle transition zone and the lower mantle roughly 410 miles (660 km) beneath the Midwest. Dubbed the "Farallon slab" and first imaged in the 1990s, this piece of oceanic crust is responsible for a process known as "cratonic thinning," according to the new study, which was published March 28 in the journal Nature Geoscience. Cratonic thinning refers to the wearing away of cratons, which are regions of Earth's continental crust and upper mantle that have mostly remained intact for billions of years. Despite their stability, cratons can undergo changes, but this has never been observed in action due to the huge geologic time scales involved, according to the study. Now, for the first time, researchers have documented cratonic thinning as it occurs. The discovery was possible thanks to a wider project led by Hua to map what lies beneath North America using a high-resolution seismic imaging technique called "full-waveform inversion." This technique uses different types of seismic waves to extract all the available information about physical parameters underground. RELATED STORIES: — Earth's layers: Exploring our planet inside and out — Scientists accidentally discover Earth's inner core is less solid than expected — Scientists discover 'sunken worlds' hidden deep within Earth's mantle that shouldn't be there "This sort of thing is important if we want to understand how a planet has evolved over a long time," study co-author Thorsten Becker, a distinguished chair in geophysics at UT Austin, said in the statement. "Because of the use of this full-waveform method, we have a better representation of that important zone between the deep mantle and the shallower lithosphere [crust and upper mantle]." To test their results, the researchers simulated the impact of the Farallon slab on the craton above using a computer model. A dripping area formed when the slab was present, but it disappeared when the slab was absent, confirming that — theoretically, at least — a sunken slab can drag rocks across a large area down into Earth's interior. Dripping beneath the Midwest won't lead to changes at the surface anytime soon, the researchers said, adding that it may even stop as the Farallon slab sinks deeper into the lower mantle and its influence over the craton wanes. The findings could help researchers piece together the enormous puzzle of how Earth came to look the way it does today. "It helps us understand how do you make continents, how do you break them, and how do you recycle them," Becker said. Originally published on
Yahoo
05-04-2025
- Science
- Yahoo
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.
Yahoo
03-04-2025
- Science
- Yahoo
A lost chunk of ancient continent is sucking bits of North America into Earth's mantle
When you buy through links on our articles, Future and its syndication partners may earn a commission. An ancient slab of Earth's crust buried deep beneath the Midwest is sucking huge swatches of present-day's North American crust down into the mantle, researchers say. The slab's pull has created giant "drips" that hang from the underside of the continent down to about 400 miles (640 kilometers) deep inside the mantle, according to a new study. These drips are located beneath an area spanning from Michigan to Nebraska and Alabama, but their presence appears to be impacting the entire continent. The dripping area looks like a large funnel, with rocks from across North America being pulled toward it horizontally before getting sucked down. As a result, large parts of North America are losing material from the underside of their crust, the researchers said. "A very broad range is experiencing some thinning," study lead author Junlin Hua, a geoscientist who conducted the research during a postdoctoral fellowship at The University of Texas (UT) at Austin, said in a statement. "Luckily, we also got the new idea about what drives this thinning," said Hua, now a professor at the University of Science and Technology of China. Related: Earth's crust is peeling away under California The researchers found that the drips result from the downward dragging force of a chunk of oceanic crust that broke off from an ancient tectonic plate called the Farallon plate. The Farallon plate and the North American plate once formed a subduction zone along the continent's west coast, with the former sliding beneath the latter and recycling its material into the mantle. The Farallon plate splintered due to the advance of the Pacific plate roughly 20 million years ago, and remnant slabs subducted beneath the North American plate slowly drifted off. One of these slabs currently straddles the boundary between the mantle transition zone and the lower mantle roughly 410 miles (660 km) beneath the Midwest. Dubbed the "Farallon slab" and first imaged in the 1990s, this piece of oceanic crust is responsible for a process known as "cratonic thinning," according to the new study, which was published March 28 in the journal Nature Geoscience. Cratonic thinning refers to the wearing away of cratons, which are regions of Earth's continental crust and upper mantle that have mostly remained intact for billions of years. Despite their stability, cratons can undergo changes, but this has never been observed in action due to the huge geologic time scales involved, according to the study. Now, for the first time, researchers have documented cratonic thinning as it occurs. The discovery was possible thanks to a wider project led by Hua to map what lies beneath North America using a high-resolution seismic imaging technique called "full-waveform inversion." This technique uses different types of seismic waves to extract all the available information about physical parameters underground. "This sort of thing is important if we want to understand how a planet has evolved over a long time," study co-author Thorsten Becker, a distinguished chair in geophysics at UT Austin, said in the statement. "Because of the use of this full-waveform method, we have a better representation of that important zone between the deep mantle and the shallower lithosphere [crust and upper mantle]." RELATED STORIES —Scientists discover 'sunken worlds' hidden deep within Earth's mantle that shouldn't be there —Earth's crust may be building mountains by dripping into the mantle —Gargantuan waves in Earth's mantle may make continents rise, new study finds To test their results, the researchers simulated the impact of the Farallon slab on the craton above using a computer model. A dripping area formed when the slab was present, but it disappeared when the slab was absent, confirming that — theoretically, at least — a sunken slab can drag rocks across a large area down into Earth's interior. Dripping beneath the Midwest won't lead to changes at the surface anytime soon, the researchers said, adding that it may even stop as the Farallon slab sinks deeper into the lower mantle and its influence over the craton wanes. The findings could help researchers piece together the enormous puzzle of how Earth came to look the way it does today. "It helps us understand how do you make continents, how do you break them, and how do you recycle them," Becker said.
