There is probably an ancient ocean floor surrounding the Earth's core.

 

In this representation of the underground imaging, seismic waves from earthquakes in the southern hemisphere sample the ULVZ structure along the Earth’s core-mantle boundary and are recorded by sensors in Antarctica. Figure courtesy of Drs. Edward Garnero and Mingming Li at Arizona State University.

Greater than the difference between solid rock and air is the absolute shift in physical qualities (such as temperature, density, and viscosity) from the mantle to the core. As a result, the Earth's core-mantle boundary (CMB) is home to a variety of phenomena, such as narrow, enigmatic regions known as ultralow velocity zones that have drastically reduced P- and S-wave velocities and increased density.

The structures in the interior of the Earth that are the most anomalous are called ultralow velocity zones (ULVZs). However, the origins of ULVZs have been a topic of discussion for decades due to the vast variety of related parameters (thickness and composition) documented by prior investigations.

 

A new study from The University of Alabama discovered extensive, varied ULVZs at the core-mantle boundary (CMB) beneath a substantial area of the Southern Hemisphere that had not before been sampled.

Using global-scale seismic imaging of the Earth's interior, research led by The University of Alabama discovered a layer between the core and the mantle that is likely a dense yet thin, hidden ocean floor.

 

 

According to the most recent studies, this ancient ocean floor layer, which was only seldom seen in small patches, may have covered the core-mantle boundary. As the Earth's plates moved long ago, they formed the ultra-low velocity zone (ULVZ), which is thicker than the rest of the deep mantle and slows seismic waves from reverberating below the surface.

"We are finding that this structure is vastly more complicated than previously thought," said Dr. Samantha Hansen, the George Lindahl III Endowed Professor in geological sciences at UA and the study's lead author. "Seismic inquiries, like ours, provide the highest resolve imaging of the inner erection of our planet. “Our research establishes crucial links between shallow and deep Earth structure and the important forces that rule our world.

 

With the use of a detailed method that examines sound wave echoes from the core-mantle barrier, the team was able to probe a sizable portion of the southern hemisphere in high resolution for the first time. Within seconds after the boundary-reflected wave, Hansen and the international team discovered unexpected energy in the seismic data.

ULVZs can be well clarified by former oceanic seafloors that ruined to the core-mantle fence. Subduction is the movement of oceanic material deep below the earth when two tectonic plates meet and one subducts beneath the other. The accumulations of oceanic material that have been subducted over the course of geologic time are pushed along the mantle-core boundary by the slowly moving rock in the mantle. The range of reported ULVZ traits can be explained by the dispersion and variability of such material.

According to Drs. Edward Garnero, Mingming Li, and Sang-Heon Shim of Arizona State University, "Our high-definition imaging method detected small anomalous zones of material at the CMB everywhere we investigated after analysing 1000s of seismic recordings from Antarctica. The thickness of the material ranges from a few kilometres to tens of kilometres. This implies that there are mountains on the core, some of which are up to five times as tall as Mount Everest.

 

These subterranean "mountains" may have a significant impact on how heat escapes from the planet's core, which is responsible for the planet's magnetic field. As a result of volcanic eruptions, material from the old ocean floors may also be entrained in mantle plumes, or hot regions, that rise to the surface.

Reference: techexplorist.com