Scientists have crafted a comprehensive map of the geology beneath the Earth's southern hemisphere. They propose that an ancient ocean floor might be enshrouding our planet's enigmatic core, potentially elucidating why the core is considerably hotter than the mantle above it. This revelation adds to the enigma of Earth's core, located roughly 1,800 miles beneath our feet.
A recent study has unveiled a discovery that could aid in unraveling the mysterious internal mechanisms of the core. The research indicates that Earth's core might be surrounded by an ancient ocean floor containing colossal mountains, which are five times the size of Mount Everest. Scientists arrived at this conclusion after creating the most detailed map to date of the geology beneath the southern hemisphere.
If verified, this "recycled" ocean floor could act like a thermal blanket, trapping heat inside the core. Samantha Hansen, the lead author of the study and a professor of geological sciences at the University of Alabama, likened Earth to a giant recycling plant.
The boundary between the mantle and the core has long puzzled scientists. Around 2,000 miles below the Earth's surface, there is a drastic change in conditions: temperatures rise sharply, and the solid rock of the mantle abruptly transitions into a molten iron sludge within the core. To study this boundary, scientists have analyzed seismic waves generated by earthquakes, which provide insights into Earth's internal structure.
Previously, scientists had detected ultra-low velocity zones (ULVZs) near the core-mantle boundary, where seismic waves slow down unexpectedly. However, these zones were only observed in isolated patches. Hansen's team went to Antarctica to investigate the extent of these ULVZs, deploying seismic equipment at 15 stations and collecting data for three years.
The discovery suggests that the ULVZs could explain the stark changes seen at the core-mantle boundary. By acting as an additional layer enveloping the core, this "blanket" could impede the escape of heat from the core. Understanding heat transfer in the core is crucial, as it influences phenomena such as mantle plumes (which create volcanic islands like Hawaii) and Earth's magnetic field.
While this discovery could offer a new chapter in the story of Earth's formation, more research is needed to eliminate other possible explanations. Some scientists speculate that the ULVZs could be caused by a completely unknown material or a specific form of melting that is not yet understood.
Hansen believes that if ULVZs are associated with subducted materials, they could provide valuable insights into plate tectonics and Earth's evolution. The findings were published in the peer-reviewed journal Science Advance in April.