Dr. James Panton and team reveal new insights into Earth's deep interior

Dr. James Panton from Cardiff University’s School of Earth and Environmental Sciences, along with researchers Huw Davies (Cardiff University), Paula Koelemeijer (University of Oxford), Bob Myhill (University of Bristol), and Jeroen Ritsema (University of Michigan), has made a major breakthrough in understanding the Earth's lower mantle.

The team’s latest research, published in Scientific Reports, sheds new light on mysterious regions beneath the Pacific Ocean and Africa, known as large low-velocity provinces (LLVPs). These deep mantle zones have unique seismic properties and are believed to contain dense, recycled oceanic crust.

Using advanced 3D simulations, the team discovered that LLVPs naturally form as recycled oceanic crust accumulates over the past billion years. Their model, which factors in the shift of tectonic plates over time, predicts the gradual buildup of two huge piles of subducted oceanic crust at the core-mantle boundary—one beneath Africa and the other beneath the Pacific.

Dr. Panton's findings challenge current understanding of these LLVP regions, indicating that these regions may have distinct evolutionary paths. Though some differences exist due to challenges in accurately modelling for past subduction zones and mantle viscosity, these findings are a step towards a greater understanding of the formation of these LLVP zones across geological time.

One key discovery is that the Pacific LLVP is constantly replenished with relatively young oceanic crust from subduction zones around the Pacific. This process has been particularly active since the breakup of Pangea around 300 million years ago. In contrast, the LLVP in Africa contains much older material that has been cycling through the mantle for a longer period. This difference in age and composition suggests that the Pacific LLVP is denser and less buoyant compared to its African counterpart.

Another fascinating finding from the simulations is that mantle plumes in the Pacific create a flow pattern that draws in newly subducted slabs, further enriching the Pacific LLVP with young oceanic crust. These results align with seismic data, which confirms that the model correctly predicts the locations of subducted slabs.

This research not only improves our understanding of mantle dynamics but also offers valuable insights into how Earth’s deep interior has changed over the past billion years.

Dr. Panton and his team’s work paves the way for future studies on mantle plumes, subduction, and the long-term recycling of oceanic crust, helping us better understand the forces shaping our planet’s geological history.

We extend our thanks to the Natural Environment Research Council (NERC) for their generous support of this project.