Earth’s oldest continental crust is slowly sinking into the mantle, a seismic discovery reveals. Previously believed to be immovable, the deep roots of Earth’s ancient continents are now seen undergoing change. In the heart of North America, sections of the deep continental base are seemingly descending into the mantle, unveiling a rare glimpse into the forces shaping our planet. This process, known as cratonic thinning, is currently unfolding beneath regions of the United States, particularly the Midwest. It involves fragments of age-old rock breaking off and moving downward in blob-like formations. This erosion of the craton, the enduring foundation of the continent for billions of years, has been captured in real time for the first time. A new seismic model named Seismic Adjoint Tomography of North America (SATONA) has unveiled long, slender blobs beneath the craton, extending from the continental lithosphere to the mantle transition zone. These drip-shaped features are believed to originate from the cratonic lithosphere. The driving force behind this phenomenon is speculated to be remnants of the ancient Farallon Plate, a tectonic plate lost to subduction under the North American Plate millions of years ago. These findings challenge the long-held stability of Earth’s cratons, showing that even the most ancient structures can undergo transformation over time.
The study revealed evidence of rock dripping from the craton, which the researchers attribute to the remnants of the subducting Farallon slab beneath the craton. This discovery suggests a link between the presence of the plate and instability at the base of the craton. The team’s computer models indicated that the inclusion of the Farallon Plate caused the craton to drip, while its removal halted the process, emphasizing the plate’s role in these geological changes.
The ongoing dripping beneath North America provides scientists with a real-time opportunity to study this phenomenon as it unfolds, offering valuable insights into the planet’s geological processes. Understanding these deep-Earth changes is crucial for comprehending how continents evolve over time, shaping landscapes, tectonic movements, and volcanic activities.
While the idea of the continent melting slowly from below may seem concerning, the process occurs over millions of years, posing no immediate danger to the surface or its inhabitants. The influence of the Farallon Plate on mantle flow can lead to thinning of the craton and the release of volatiles, potentially affecting a broader area than previously thought.
These discoveries mark a significant advancement in the understanding of Earth’s long-term evolution, providing valuable insights into the complex interactions between the deep mantle and the lithosphere. The findings not only shed light on the past but also pave the way for future research on the dynamic processes shaping our planet.
Remnants of the same plate are restructuring the continent from below. “When you look at a model, you have to ask yourself, ‘Is it real? Are we interpreting the data correctly, or is it revealing something new about Earth?'” Becker remarked. “But in many instances, it appears that these anomalous formations are transient. They are indeed a tangible phenomenon.” Enhanced data-fitting through inversion techniques. (CREDIT: Nature Geoscience) Reevaluating the Lifespan of Continents The long-standing belief that continents are permanent fixtures on Earth has been challenged. Cratons, in particular, were once regarded as impervious to the processes of renewal and transformation that impact other regions of our planet. However, recent findings indicate that even the most ancient parts of Earth are subject to change and potential disappearance. This breakthrough not only reshapes our understanding of North America but also revolutionizes the concept of continental life cycles in general. It suggests that external influences, such as deep mantle movements attributed to a long-extinct tectonic plate, can gradually alter even the most stable sections of the Earth’s crust. With the aid of advanced tools like SATONA and comprehensive seismic data provided by initiatives like EarthScope, scientists now possess the capability to peer more deeply into the Earth’s interior. This newfound clarity may lead to the discovery of additional instances of ongoing geological processes that were formerly concealed from view. In the words of Hua, “Our observation revealed the presence of something beneath the craton. Fortunately, it also sparked a fresh perspective on the driving forces behind this thinning.” As tectonic plates continue to shift and mantle materials flow, the ancient regions of Earth may undergo gradual but significant changes, with profound implications for the future of the continents we inhabit. Note: The Brighter Side of News has provided the article above. Enjoy uplifting stories like this? Subscribe to The Brighter Side of News’ newsletter.
