Tag Archives: mantle

Earth Scientists Uncover the Mystery Behind Intriguing Structures in the Mantle

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For many years, researchers have been intrigued by two massive structures hidden deep beneath the Earth’s surface. These anomalies might possess geochemical characteristics that differ from the surrounding mantle, yet their source remains unclear. Geodynamicist Yoshinori Miyazaki from Rutgers University and his team offer an unexpected explanation regarding these anomalies and their significance in influencing Earth’s capacity to sustain life.

This diagram shows a cross-section that reveals the interior of the early Earth, featuring a hot molten layer situated above the core-mantle boundary. Image credit: Yoshinori Miyazaki/Rutgers University.

The two enigmatic structures, referred to as large low-shear velocity regions and ultra-low velocity regions, lie at the boundary between the Earth’s mantle and core, approximately 2,900 km (1,800 miles) beneath the Earth’s exterior.

Large low-shear velocity regions are vast, continent-sized masses of hot and dense rock.

One of these regions is located beneath Africa, while the other is situated beneath the Pacific Ocean.

The ultra-low velocity zone resembles a thin layer of melt that adheres to the core much like a puddle of molten rock.

Both structures significantly slow seismic waves and display unusual compositions.

“These are not random, odd phenomena,” Dr. Miyazaki, co-author of a related paper published in the journal Nature Earth Science, explained.

“They represent traces of Earth’s primordial history.”

“Understanding their existence could help us unravel how our planet formed and what made it habitable.”

“Billions of years in the past, the Earth was covered by an ocean of magma.”

“While scientists anticipated that as the mantle cooled, it would establish distinctive chemical layers—similar to how frozen juice separates into sweet concentrate and watery ice—seismic surveys have shown otherwise. Instead, large low-shear velocity regions and ultra-low velocity zones appear as irregular accumulations at the Earth’s depths.”

“This contradiction sparked our inquiry. When starting with a magma ocean and performing calculations, the outcome does not match the current observations in the Earth’s mantle. A critical factor was missing.”

The researchers propose that over billions of years, elements such as silicon and magnesium may have leached from the core into the mantle, mixing with it and hindering the development of pronounced chemical layers.

This process could clarify the bizarre structure of the large low-shear velocity and ultra-low velocity regions, potentially visibly representing the solidified remnants of a basal magma ocean tainted by core materials.

“What we hypothesized is that this material could be leaking from the core,” Dr. Miyazaki noted.

“Incorporating core components might account for our current observations.”

“This discovery goes beyond merely understanding the chemistry of the deep Earth.”

“Interactions between the core and mantle may have shaped the Earth’s cooling process, volcanic activity, and atmospheric evolution.”

“This could help clarify why Earth possesses oceans and life, while Venus is a frigid hothouse and Mars a frozen wasteland.”

“Earth has water, life, and a relatively stable atmosphere.”

“In contrast, Venus’ atmosphere is over a hundred times thicker than Earth’s and is mainly carbon dioxide, while Mars’ atmosphere is much thinner.”

“While we do not fully comprehend why this is the case, the processes occurring within the planet—its cooling and layer evolution—could be a significant part of the explanation.”

By synthesizing seismic data, mineral physics, and geodynamic modeling, the authors reaffirm that the extensive low-shear velocity regions and ultra-low velocity zones offer crucial insights into Earth’s formative processes.

These structures may also contribute to volcanic hotspots like those in Hawaii and Iceland, thereby connecting deep Earth dynamics to the planet’s surface.

“This study exemplifies how the integration of planetary science, geodynamics, and mineral physics can aid in unraveling some of Earth’s long-standing enigmas,” said co-author Dr. Jie Deng, a researcher at Princeton University.

“The notion that the deep mantle may still retain the chemical memory of ancient core-mantle interactions provides fresh perspectives on Earth’s unique evolution.”

“Every new piece of evidence contributes to piecing together Earth’s early narrative, transforming scattered hints into a more coherent picture of our planet’s development.”

“Despite the limited clues we have, we are gradually forming a significant narrative,” Dr. Miyazaki remarked.

“With this research, our confidence in understanding Earth’s evolution and its distinctiveness can now be bolstered.”

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J. Deng et al. 2025. Heterogeneity in the deep mantle formed through a basal magma ocean contaminated by core materials. Nature Earth Science 18, 1056-1062; doi: 10.1038/s41561-025-01797-y

Source: www.sci.news

Frozen Evidence of Mars’ Turbulent Origins Found in Its Mantle, Study Indicates

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The mantle of Mars houses ancient fragments measuring up to 4 km in width from its formation, as revealed by an analysis of seismic data gathered by NASA’s InSight Mission.

The immense collisions during early Mars’ history resulted in a global ocean of magma. Image credit: Vadim Sadovski / Imperial College London.

The planet’s mantle serves as a significant layer, located between the crust and core, preserving vital evidence about its formation and evolution.

In contrast to Earth, where active plate tectonics constantly mix the mantle, Mars functions as a smaller planet with a single plate surface.

This results in considerably less mixing of the Martian mantle, which may retain records of early internal history, providing valuable insights into the formation and evolution of rocky worlds.

Utilizing data from NASA’s InSight Lander, Dr. Constantinos Charalambous from Imperial College London and his colleagues analyzed the seismic signatures of Marsquakes to better understand the composition of the Martian mantle.

They studied eight recorded quakes, including those triggered by the impact of meteorites, discovering that the arrival of high-frequency P-waves is consistently delayed as they traverse deeper regions of the mantle.

The authors suggest that these delays indicate variations in the composition of the mantle stretching over kilometers.

Given that Mars lacks plate tectonics and large-scale recycling processes, these minor irregularities are likely remnants of its formative history.

Investigating the heterogeneity of the Martian mantle implies that it results from an intense and destructive process, reflecting the significant events of the planet’s early history that caused extensive interior disruption and mixed both foreign and crustal materials at a planetary scale.

Furthermore, additional variations might have arisen from the vast ocean of crystallized magma formed during this aftermath.

Rather than being erased, these features were preserved as the Martian crust cooled and mantle convection ceased.

“The seismic signals displayed clear signs of interference while traveling deep within Mars,” Dr. Charalambous noted.

“This coincides with a mantle composed of structures originating from various compositions, representing Mars’ early remnants.”

“What occurred on Mars is that following these initial events, the surface hardened into a stagnant lid.”

“It became isolated from the mantle, entrapping ancient, chaotic features like planetary time capsules.”

“Our observations reveal the distribution of fractals, where energy from violent collisions exceeds an object’s strength.”

“This mirrors the effect seen when glass falls onto a tiled floor, akin to meteorite impacts with a planet. It results in the formation of both large and small fragments.”

“It’s astonishing that we can still detect this distribution today.”

“The Jet Propulsion Research Institute” stated Dr. Mark Panning, a researcher at NASA’s Jet Propulsion Laboratory.

“It’s exhilarating to witness scientists uncovering new findings through the earthquakes we observe!”

The team’s paper was published today in the journal Science.

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Constantinos Charalambous et al. 2025. Evidence of a highly uneven Mars mantle inferred from earthquake analysis. Science 389 (6763): 899-903; doi: 10.1126/science.adk4292

Source: www.sci.news

Geoscientists Discover Pulsating Mantle Plume Beneath Remote Area of Ethiopia

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According to a study led by researchers at the University of Southampton, these pulses are gradually tearing apart the African continent, resulting in the formation of a new sea basin.

Variation of geochemical and geophysical properties around distant triangles. Image credit: Watts et al, doi: 10.1038/s41561-025-01717-0.

The AFAR region stands out as a unique site on Earth where three structural lifts converge: the main Ethiopian rifts, the Red Sea rifts, and the Gulf of Aden lifts.

Geologists have speculated for some time that a thermal upwelling from the mantle, commonly referred to as plumes, exists beneath this area and promotes the extension of the crust along with the formation of upcoming sea basins.

However, the details regarding the structure of this upwelling and its behavior beneath the lifting plate have remained largely unknown until now.

“Our findings indicate that the mantle below the region is uniform but not stationary; it exhibits a pulsing nature that carries a unique chemical signature,” explained Dr. Emma Watts, who led the study at the University of Southampton and is currently at Swansea University.

“These rising pulses from the partially melted mantle are directed by the overlying filling plate.”

“This insight is crucial for understanding the interaction between the Earth’s interior and its surface.”

Dr. Watts and her team collected over 130 volcanic rock samples from remote areas and significant Ethiopian rifts.

Additionally, they utilized existing data and sophisticated statistical modeling to examine the structure of the crust and mantle, along with the melts within.

Their research reveals a single asymmetric plume beneath the distant region, showcasing distinct chemical bands that recur throughout the lift system, akin to geological barcodes.

These patterns vary in spacing according to the structural conditions of each lift arm.

“The observed chemical stripes imply that the plume pulsates like a heartbeat,” remarked Professor Tom Gernon from the University of Southampton.

“These pulses seem to behave differently based on the thickness of the plate and the rate at which it is pulled apart.”

“In faster-spreading rifts like the Red Sea, the pulsation occurs more efficiently and regularly, similar to a pulse flowing through a narrow artery.”

The findings illustrate that the mantle plume beneath the distant region is dynamic, reacting to the tectonic plate above it.

Dr. Derek Kiel, a researcher at the University of Southampton and the University of Florence, stated:

“This has significant implications for interpreting processes related to surface volcanism, seismic activity, and continental splitting.”

“Our work indicates that deep mantle upwellings flow beneath the tectonic plate, concentrating volcanic activity in the thinnest areas.”

“Understanding the rate and manner of mantle flow beneath the plate is crucial for further research.”

“Collaborating with experts from various fields within the institution, as we did for this project, is vital for uncovering the processes that occur beneath the Earth’s surface and their link to recent volcanic activity,” Dr. Watts emphasized.

“It’s challenging to see the broader picture, akin to assembling a puzzle without all the pieces unless we employ diverse techniques.”

study published in the journal Natural Earth Science.

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ej watts et al. Mantle upwelling at an afor triple junction influenced by the dynamics of the overriding plate. Nat. Geosci Published online on June 25, 2025. doi:10.1038/s41561-025-01717-0

Source: www.sci.news

Hidden Plumes in Earth’s Mantle May Drain Heat from the Core

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The Al Haja Mountains of Oman

l_b_photography/shutterstock

Researchers have discovered the first known “ghost plume” beneath Oman, suggesting a column of hot rock rising from the lower mantle with no visible volcanic activity on the surface.

The mantle plume is a mysterious intrusion of molten rock believed to transfer heat from the core-mantle boundary to the Earth’s surface, sometimes occurring beneath the heart of continental plates, as seen in regions like Yellowstone and East Africa. Notably, “these scenarios typically feature surface volcanoes,” states Simone Pilia from King Fahd University of Petroleum and Minerals in Saudi Arabia. Oman lacks such volcanic indicators.

Pilia first hypothesized the existence of this “accidental” plume while examining new seismic data from Oman. The analysis revealed that seismic waves from distant earthquakes travel more slowly through a cylindrical region beneath eastern Oman, indicating it is less dense than surrounding materials due to elevated temperatures.

Additional independent seismic assessments identified critical boundaries where Earth’s deep minerals undergo changes that align with the hot plume’s characteristics. This evidence suggests the plume extends over 660 km from the surface.

The presence of these plumes also explains why the region continues to elevate despite geological compression, a process where the crust is squeezed together. This discovery fits models that explain alterations in Indian tectonic plate movements.

“The more evidence we collected, the more convinced we became it was a plume,” remarks Pilia, who has named this geological feature the “Dinni plume” after her son.

“It’s plausible that this plume exists,” agrees Saskia Goes at Imperial College London, adding that this study is “thorough.” Nevertheless, she emphasizes that identifying narrow plumes is notoriously challenging.

If verified, the existence of a “ghost plume” trapped within Oman’s relatively thick rocky layers suggests there might be others. “We are confident that the Dinni plume is not alone,” says Pilia.

If multiple hidden plumes exist, it could indicate that heat from the core is transferring more readily through the mantle in these regions, influencing our understanding of Earth’s evolutionary history.

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Source: www.newscientist.com

Human activity has profound impacts on the Earth’s upper mantle

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Ship cemetery in the desert of the Aral Sea in Uzbekistan

s@owwl / alamy

Unsustainable irrigation and drought have caused changes that have empty almost all of the waters of the Aral Sea since the 1960s, extending all the way to the Earth’s upper mantle, the layer below the Earth’s crust. This is perhaps the deepest recorded example of human activity that will change the solid inner earth.

“To do something that will affect us [upper mantle] It’s like whoa.” Sylvain Barbott At the University of Southern California. “It shows how powerful it is to change the environment.”

The Aral Sea in Central Asia was once one of the largest waters in the world, covering almost 70,000 square kilometers. However, Soviet irrigation programs that began in the 1960s and later droughts empty the oceans. By 2018, it had shrunk by almost 90% and lost about 1,000 cubic kilometres of water.

Wang Ten At Peking University in China, I was interested in the Aral Sea after reading a book about the consequences of this environmental disaster on the surface of the earth. “We’ve noticed that these huge mass changes stimulate the deep Earth’s response,” he says.

He and his colleagues, including Barbot, used satellite measurements to track subtle changes in the elevation of the oceans that were empty between 2016 and 2020. Much of the ocean water disappeared decades ago, but it was found that the uplifts were underway, with on average rising surfaces about 7 millimeters a year.

Next, we used a model of the crust and mantle beneath the Aral Sea to test the mantle beneath the Aral Sea when it came to leading to the uplift of this observed pattern. “We found that the observations were perfectly compatible with a deep response to this change,” says Barbot.

When the weight of the water was removed, the shallow crust first responded, according to the model. This prompted a response at a depth of 190 km from the surface as the viscous rocks in the upper mantle creeped up to fill the blanks. “The uncurved things create space and the rocks want to flow into it,” Barbot says. This delayed reaction in hot, weak areas of the mantle, called the athenosphere, is why the uplift is ongoing, even decades after the water is removed, he says.

The upper mantle rebound is known to occur after other major changes in surface mass, such as glacier advancement and retreat, says Roland Bürgmann At the University of California, Berkeley. But the response to drainage in the Aral Sea may be the deepest example of human-caused changes on solid earth.

Other human-induced changes, such as filling large reservoirs and pumping groundwater, are said to have also caused rebounds. Manoochehr Shirzaei At Virginia Tech. But the wider range of the Aral Sea means the impact of emptying it is likely to run deeper, he says.

In addition to explaining the enormous scale of human activity, the uplift below the Aral Sea offers an extraordinary opportunity to estimate small differences in viscosity of the mantle, particularly under the interior of the continent, Bürgmann says. “It’s really important for people trying to understand plate tectonics to know how that layer behaves under the continent.”

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Source: www.newscientist.com

New: Groundbreaking drill core penetrates 1.2 kilometers into Earth’s mantle

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A rock sample from Earth’s mantle viewed under a microscope

Johan Lissenberg

In the middle of the North Atlantic, geologists have drilled 1,268 metres below the seafloor – the deepest hole ever drilled into Earth’s mantle – and analysis of the resulting rock core may provide new clues about the evolution of the planet’s outermost layers and even the origin of life.

The Earth is generally made up of several different layers, including the solid outer crust, the upper and lower mantle, and the core. The upper mantle, located just below the crust, is made up primarily of magnesium-rich rocks called peridotites. This layer drives important planetary processes such as earthquakes, the hydrological cycle, and the formation of volcanoes and mountain ranges.

“Until now, we’ve only been able to see fragments of the mantle,” Johan Lissenberg “However, there are many places on the seafloor where the mantle is exposed,” said researchers from Cardiff University in the UK.

One such region is an underwater mountain called Atlantis Mountains, located near a volcanically active area of the Mid-Atlantic Ridge. Pieces of the mantle constantly come to the surface and melt, giving rise to the region’s many volcanoes. Meanwhile, as seawater seeps deeper into the mantle, it is heated by higher temperatures, producing compounds such as methane, which bubbles up from hydrothermal vents and serves as fuel for microorganisms.

“There’s a kind of chemical kitchen beneath the Atlantis massif,” Lisenberg says.

To learn more about this dynamic region, he and his colleagues initially planned to use the drilling ship JOIDES Resolution to drill 200 meters into the mantle, deeper than researchers had gone before.

“We then started drilling and it went surprisingly well,” a team member said. Andrew McCaig “We retrieved a very long continuous fragment of rock and decided to go for it and go as deep as we could,” said researchers from the University of Leeds in the UK.

Ultimately, the team succeeded in drilling to a depth of 1,268 metres into the mantle.

When the researchers analyzed the drill core samples, they found that they had a much lower content of a mineral called pyroxene compared to other mantle samples from around the world, suggesting that this particular part of the mantle underwent significant melting in the past, depleting it of pyroxene, Lisenberg said.

In the future, he hopes to recreate this melting process, which will allow him to understand how the mantle melts and how that molten rock travels to the surface to feed oceanic volcanoes.

Some scientists believe life on Earth began deep in the ocean near hydrothermal vents, so by studying the chemicals that show up along the cylindrical rock cores, microbiologists hope to determine the conditions that may have led to the emergence of life, and at what depths below the ocean floor.

“This is a very important borehole because it will provide a reference point for scientists across many scientific disciplines,” McCaig says.

“While a one-dimensional sample from Earth cannot provide complete information about the three-dimensional migration paths of melt and water, it is still a major achievement,” he said. John Wheeler At the University of Liverpool, UK.

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Source: www.newscientist.com