Researchers have recently made a significant discovery about Earth's mantle by analyzing seismic data. Seismic waves generated by earthquakes provide valuable insights into the Earth's interior composition and structure.
In this study, scientists used data from seismic monitoring stations in Antarctica to create a high-resolution map of the Earth's Southern Hemisphere. By analyzing how seismic waves travel through the planet, researchers identified areas where the waves moved more slowly, known as ultralow velocity zones (ULVZs). These regions are found at the core-mantle boundary (CMB), around 2,900 kilometres (1,800 miles) beneath the Earth's surface.
The suggestion that these ULVZs contain remnants of an ancient ocean floor makes this discovery particularly intriguing. The ULVZs are believed to be sunken oceanic crust that has settled at the CMB over millions of years. The researchers propose that convection currents within the Earth's mantle may have transported this ocean floor to its current location, even though it is not near typical subduction zones where tectonic plates converge. Material is pushed into the Earth's interior.
The study also speculates that this ancient ocean crust could encircle the entire core, though its thinness makes it challenging to confirm. Further seismic surveys are expected to provide additional information about the extent of this discovery.
Understanding the presence of this ancient ocean floor at the CMB has important implications for geology and Earth sciences. It sheds light on the processes responsible for heat transport from the Earth's core to the mantle. The differences in composition between these two layers are significant, and this knowledge could enhance our understanding of various geological phenomena, including volcanic eruptions and the Earth's magnetic field, which shields us from solar radiation.