Recent research led by geophysicists from the Swiss Federal Institute of Technology in Zurich and the California Institute of Technology (Caltech) has revealed previously unknown rock zones in the Earth's lower mantle. This discovery, published on November 4, 2024, in the journal Nature, challenges existing understandings of plate tectonics.
Traditionally, geographers have relied on seismographs to study the Earth's internal structure, using seismic waves from earthquakes to map tectonic plate boundaries. However, the new study employed a high-resolution model of the Earth's mantle, utilizing an advanced geophysical imaging technique known as Full Waveform Inversion. This method allows for a more accurate estimation of subsurface material properties by analyzing the propagation of seismic waves.
The researchers identified submerged rock zones beneath the oceans and within continents that do not align with known tectonic boundaries. One significant zone was discovered under the western Pacific Ocean, adjacent to another previously identified area, which was thought to be impossible.
Thomas Schouten, the lead author and doctoral student at ETH Zurich, stated, “These zones in the Earth's mantle appear to be more widespread than previously believed.” The nature of these anomalies remains uncertain, with potential origins including ancient silica-rich material dating back to the formation of the mantle approximately 4 billion years ago, or areas where iron-rich rocks have accumulated due to mantle convection over billions of years.
This groundbreaking research underscores the need for further investigation to enhance our understanding of Earth's internal dynamics.