In a groundbreaking expedition, scientists have successfully drilled deeper into the Earth’s mantle than ever before. This achievement was part of a mission conducted in May 2023, where researchers extracted their deepest core sample yet—a remarkable 1,268-meter core containing serpentinized peridotite, a rock formed through the interaction between saltwater and mantle rock.
The mission, executed by the International Ocean Discovery Program (IODP) aboard the JOIDES Resolution, aimed to better understand the mantle, which constitutes 70 percent of the Earth’s mass and 84 percent of its volume. Despite its significance in geological processes, direct sampling of mantle rocks has remained elusive until now. The drill site was strategically located near the Mid-Atlantic Ridge, in an area known as the Lost City, where geological conditions allow direct access to mantle materials.
Johan Lissenberg, a co-author of the study and petrologist at Cardiff University, noted that the team originally planned to drill only 200 meters, the previous record for mantle rock drilling. However, favorable drilling conditions allowed them to go much deeper—three times faster than anticipated. Preliminary analyses revealed that the core contains harzburgite, a variety of peridotite formed via partial melting of mantle rock, and gabbros, which are coarse-grained igneous rocks that have chemically interacted with seawater.
While this extensive drilling provided invaluable insights into the mantle’s composition, the expedition did not manage to cross the MohoroviÄić discontinuity, commonly referred to as the Moho. The Moho is the critical boundary between the Earth’s crust and the underlying mantle, representing a major target for future explorations.
Despite the success of this mission, the prospects for further drilling efforts beyond 2024 are uncertain, as funding from the U.S. National Science Foundation will no longer support the continuation of such missions. As scientists reach the threshold of this fundamental layer of Earth’s geology, the ability to conduct further studies hangs in the balance, leaving future exploration of the Earth’s mantle in jeopardy.
The findings from this mission, documented in the journal *Science*, pave the way for a deeper understanding of Earth’s early history and the geological processes that shape our planet.
