Mysteries of Earth’s Deep Mantle and Theia’s Remains Unveiled
Deep within Earth’s mantle lie two enormous, iron-dense structures, which a recent study led by Caltech indicates are remnants of Theia. This ancient planet is believed to have violently collided with Earth, leading to the formation of the Moon. This finding addresses the age-old questions about the origins of the Moon and the whereabouts of Theia.
During the 1980s, geophysicists unearthed a groundbreaking revelation: two colossal blobs of unusual matter, each twice the Moon’s size, located near Earth’s center. These were identified beneath the African continent and the Pacific Ocean, and their elemental composition differed from the adjacent mantle.
These unusual formations, known as large low-velocity provinces (LLVPs), have puzzled scientists. Caltech researchers now postulate that they are remnants of Theia, which collided with Earth billions of years ago in a mammoth impact that also birthed our Moon.
The study, which graced the pages of the journal “Nature” on November 1, also presents a solution to another enigma in planetary science. For a long time, researchers speculated that the Moon was birthed from a colossal collision between Earth and a smaller planet, named Theia. However, no evidence of Theia was identified in the asteroid belt or meteorites. The current research posits that the majority of Theia integrated into the nascent Earth, shaping the LLVPs. The residual debris from this collision amalgamated to form the Moon.
Qian Yuan spearheaded the research in collaboration with Paul Asimow and Michael Gurnis at Caltech. These mysterious LLVPs were initially identified by observing seismic waves traversing Earth. Seismic waves vary in speed based on the materials they travel through. The deepest mantle displays a seismic wave pattern influenced predominantly by the two immense structures near Earth’s core, believed to have an unusually high iron content. These iron-rich regions, denser than their adjacent areas, slow down seismic waves, thus earning the designation “large low-velocity provinces.”
At a 2019 seminar on planet formation by Mikhail Zolotov, a professor at Arizona State University, Yuan had a revelation. When Zolotov discussed the Moon’s significant iron content and the missing impactor, Yuan postulated that this iron-rich impactor might have metamorphosed into the mantle blobs.
Subsequent modeling of Theia’s chemical composition and its potential impact with Earth by Yuan and a multi-disciplinary team confirmed that the collision physics could have spawned both the LLVPs and the Moon. Part of Theia’s mantle might have merged with Earth’s mantle, coalescing and crystallizing to give rise to the two distinguishable blobs observed today at Earth’s core-mantle boundary. Conversely, other debris from this collision combined to create the Moon.
The research further delves into why Theia’s material formed two distinct blobs rather than mixing with the nascent planet. Simulations illustrated that a significant portion of the energy from Theia’s impact was confined to the upper half of the mantle, keeping the lower mantle cooler than previously estimated. This meant that the iron-rich Theia material largely remained intact, settling at the base of the mantle in a manner reminiscent of an inactive lava lamp. A hotter lower mantle would have blended more thoroughly with the iron-rich material.
The researchers now aim to explore the implications of Theia’s material’s early presence deep within Earth and its influence on internal planetary processes like plate tectonics.
In Asimow’s words, considering the LLVPs as remnants of Theia implies their ancient nature. Hence, the next logical step is to investigate their role in Earth’s primal evolution, such as the onset of subduction before conditions became conducive to contemporary plate tectonics, the creation of the first continents, and the inception of the oldest enduring terrestrial minerals.
This groundbreaking study not only deciphers the enigmatic “blobs” near Earth’s core but also sheds light on the fate of the planet that collided with Earth to give birth to the Moon. The remnants of this ancient planet, Theia, are believed to still reside within Earth, elucidating the mysteries of the core-mantle boundary.
Reference: “Moon-forming impactor as a source of Earth’s basal mantle anomalies” by Qian Yuan et al., 32 October 2023, Nature. DOI: 10.1038/s41586-023-06589-1
Qian Yuan is the primary author, with additional contributions from various esteemed scientists from institutions such as Caltech, Arizona State University, Michigan State University, the Chinese Academy of Sciences, the U.S. Geological Survey, NASA’s Ames Research Center, and Durham University. The research received funding from numerous sources, including the National Science Foundation, the O.K. Earl Postdoctoral Fellowship at Caltech, the U.S. Geological Survey, NASA, and the Caltech Center for Comparative Planetary Evolution.
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Frequently Asked Questions (FAQs) about fokus keyword: Earth’s Mantle Theia Remnants
What are the large low-velocity provinces (LLVPs) in Earth’s mantle?
LLVPs, or large low-velocity provinces, are two immense, iron-dense structures located deep within Earth’s mantle. They are unusual formations that were discovered in the 1980s, with each blob being twice the size of the Moon and having an elemental composition different from the adjacent mantle.
How are the LLVPs connected to the ancient planet Theia?
A recent study led by Caltech postulates that these LLVPs are remnants of Theia, an ancient planet that collided with Earth billions of years ago. This massive impact also resulted in the formation of our Moon.
How were the LLVPs initially discovered?
Scientists first discovered the LLVPs by observing seismic waves traversing Earth. These seismic waves vary in speed based on the materials they travel through. The presence of these iron-rich regions, which are denser than their surrounding areas, causes seismic waves passing through them to slow down, leading to their identification.
Why did Theia’s material form distinct blobs rather than mix with the forming Earth?
Researchers’ simulations indicated that much of the energy from Theia’s impact was confined to the upper half of the mantle. This kept Earth’s lower mantle cooler than earlier estimates, allowing the iron-rich material from Theia to remain largely intact as it settled at the base of the mantle.
What are the implications of the findings regarding Theia’s remnants in Earth’s mantle?
These findings provide insights into Earth’s primal evolution, including the onset of processes like subduction before the development of modern plate tectonics, the creation of the first continents, and the origin of the oldest enduring terrestrial minerals.
Who led the research on the LLVPs and their connection to Theia?
The research was spearheaded by Qian Yuan, in collaboration with Paul Asimow and Michael Gurnis at Caltech.
What is the significance of the findings regarding the Moon’s formation?
The study presents a solution to a long-standing question in planetary science. Researchers had long speculated about the Moon’s formation from a collision between Earth and a smaller planet, Theia. The study suggests that while most of Theia was integrated into the nascent Earth, forming the LLVPs, the residual debris from this collision amalgamated to form the Moon.
More about fokus keyword: Earth’s Mantle Theia Remnants
- Caltech’s official website
- Nature Journal’s official page
- Introduction to Earth’s Mantle
- Overview of Seismic Waves
- The Moon-forming Giant Impact Hypothesis
- The Mystery of Earth’s Core-Mantle Boundary
- Research about Theia and its Collision with Earth
- Understanding Large Low-Velocity Provinces (LLVPs)
