Unexpected tectonic mysteries beneath the Pacific unveiled
Geologists from ETH Zurich and the California Institute of Technology studying the Earth's interior using seismic waves have encountered an intriguing phenomenon beneath the Pacific Ocean. The analysis of wave movement revealed the existence of zones with different properties, suggesting that there are structures there with lower temperatures or a different chemical composition compared to the surrounding magmatic rocks.
The discovery, described in the scientific journal "Scientific Reports," concerns areas that resemble fragments of tectonic plates submerged in subduction zones (i.e., places where tectonic plates dive back into the Earth's mantle). However, under the Pacific, which is one large plate, such remnants shouldn't exist. Researchers are uncertain about the material composition of these deep structures or their significance for Earth's geological history.
Mysterious structures beneath the Pacific
"That's our dilemma. With the new high-resolution model, we can see such anomalies everywhere in the Earth's mantle. But we don't know exactly what they are or what material is creating the patterns we have uncovered," said Thomas Schouten, a doctoral student at the Institute of Geology at ETH Zurich, quoted by IFL Science.
Researchers speculate that the presence of so many cold regions may indicate their diverse origins. As IFL Science reports, some of these structures may have formed billions of years ago and survived the dynamic movements of the Earth's mantle.
"We think that the anomalies in the lower mantle have a variety of origins," explained Schouten. "It could be either ancient, silica-rich material that has been there since the formation of the mantle about 4 billion years ago and has survived despite the convective movements in the mantle, or zones where iron-rich rocks accumulate as a consequence of these mantle movements over billions of years," he added.
Although the latest models provide detailed data, scientists emphasise that current research is based on the analysis of a single parameter – the speed of seismic waves. This limitation hinders the accurate interpretation of results.
"We have to calculate the different material parameters that could generate the observed speeds of the different wave types. Essentially, we have to dive deeper into the material properties behind the wave speed," noted Schouten.
