Lost Seafloor from Dinosaur Era Discovered Beneath the Pacific

Scientists have discovered what they refer to as a “fossilized fingerprint” of a piece of ancient seafloor submerged beneath the Pacific Ocean. This finding, detailed in a recent study published in the journal Science Advances on September 27, traces back to a slab of Earth’s crust that began its descent into the mantle around the start of the dinosaur era, approximately 250 million years ago.

Originally part of the seafloor in the southeastern Pacific, this slab now rests within the mantle transition zone, located between 410 to 660 kilometers deep under the Earth’s surface. This area, which experiences fluctuations due to thermal currents, was scrutinized by researchers led by Jingchuan Wang, a seismologist and postdoctoral associate at the University of Maryland.

The discovery occurred during an exploration of the mantle beneath the East Pacific Rise, a mid-ocean ridge some 3,200 kilometers from the South American coast. The team employed seismic waves to investigate the rock types under the seafloor, creating a digital cross-section of the Earth’s crust and mantle in the process. They identified a notably thickened area of the mantle transition zone roughly 350 kilometers east of Easter Island, which Wang likened to the fossilized remains of the ancient seafloor that once submerged into the Earth.

Unlike typical subducted material that disintegrates in the mantle and converts into magma due to intense heat, this particular slab has managed to avoid such a fate. Subduction generally happens when two tectonic plates collide, with one plate diving below the other, usually moving quickly through the mantle. However, Wang suggested that the mantle transition zone might act as a viscous barrier that slows down the sinking process, preserving remnants like this one.

Wang emphasized the significance of this find as it provides an unprecedented look into Earth’s geological history. He expressed optimism about discovering more such ancient structures within the deep layers of the Earth, marking this as just the beginning of their research into Earth’s deep-seated past.