Ancient ocean crust discovered beneath southeastern Pacific near Easter Island

In a groundbreaking study published on September 27, researchers unveiled a significant discovery beneath the southeastern Pacific Ocean, specifically near Easter Island, Chile. They created a seismic map revealing an ancient slab of oceanic crust that has become trapped in the mantle transition zone, a layer situated between 255 and 410 miles deep. This slab, which once formed part of the seafloor, is believed to have traveled through the mantle at a slower rate than typical subducting plates, suggesting that the transition zone can act as a barrier to the movement of sinking materials. The study's lead author, Jingchuan Wang, emphasized that this finding provides a unique glimpse into Earth's geological history, as the slab's preservation challenges the common understanding of how oceanic crust is usually recycled into the mantle. The researchers utilized seismic waves to analyze the rock types beneath the seafloor, leading to the creation of a digital cross-section of Earth's crust and mantle. The discovery of this thickened mantle transition zone, which acts like a fossilized fingerprint of the ancient seafloor, could help explain a peculiar gap in the lower mantle known as the Pacific Large Low Shear Velocity Province (LLSVP). The mass of the slab may be influencing the lower boundary of this region, indicating a complex interaction between the slab and the surrounding mantle materials. Wang concluded that this discovery is just the beginning, with many more ancient structures likely hidden within Earth's depths, each holding the potential to enhance our understanding of the planet's intricate geological past and possibly other celestial bodies.