Scientists lift a kilometer of rock from Earth’s mantle to the surface

The result was obtained by drilling in the Atlantis Massif, a seamount located on the Mid-Atlantic Ridge, deep in the North Atlantic Ocean. Geologists conducting a drill at this location dug a 1,267-metre-deep hole and extracted “astonishing” amounts of serpentinites—metamorphic rocks formed at the deep boundaries of tectonic plates—from the bowels of the Earth.

What scientists have learned

It’s worth noting that this isn’t the deepest state the drill has ever sunk in. What’s more, it technically didn’t dig through the earth’s mantle. To sink the drill bit and remove the material, the researchers used a “tectonic window”—an area where mantle rocks were pushed above their normal position.

Access to mantle rocks on Earth is often extremely difficult. The Atlantis Massif offers a rare access advantage as it consists of mantle rocks that were lifted closer to the surface by ultra-slow seafloor spreading.
– geologists write on their blogs.

Geologists have been trying to extract significant volumes of Earth’s mantle since 1961, but all previous attempts have failed. This meant that scientists had to rely on fragments of rock ejected during volcanic eruptions to examine parts of the Earth’s mantle for clues to processes as diverse as volcanism and the planet’s magnetic field. The problem is all changed during their trip to the surface, so they didn’t give the full picture.

Geologists, participants of the International Program of Ocean Exploration aboard the scientific drilling vessel JOIDES Resolution, went to the Atlantis massif not because they wanted to extract mantle cores, but because they were looking for the origins of life on Earth. Massive rocks contain olivine, which reacts with water during the serpentinization process to form hydrogen, an essential nutrient for microbial life.

However, shortly after May 1, when they plunged a drill into a fault in the seafloor, the researchers extracted a record core from upper mantle rock. The rock was mainly peridotite, a coarse igneous rock filled with olivine and pyroxene. It is the most common type of rock in the upper mantle. Some signs that the rock was modified by interacting with seawater could mean it came from the lower crust rather than the upper mantle, but scientists are still digging deeper samples. Within these rocks lies a wealth of information that geologists will explore to learn more about the Earth’s interior.