For the first time, scientists have drilled into an underwater mountain to collect a record-breaking piece of Earth’s mantle — a rocky core more than 3,280 feet (one kilometer) across.
This amazing feat was achieved by drilling in the Atlantis Massif, an underwater mountain located on the Mid-Atlantic Ridge under the North Atlantic Ocean. By aligning drills at this site, geologists have drilled a 4,156-foot (1,267-meter) deep hole in the mountain and extracted an “astonishing” amount of serpentine — metamorphic rocks that form at deep tectonic plate boundaries — from Earth’s interior.
Despite the groundbreaking results, this isn’t the deepest drill ever conducted on the sea floor, and technically speaking, it didn’t drill into the Earth’s mantle. Instead, the researchers exploited the “tectonic window”—the area where mantle rocks have been pushed above their usual resting place—to sink the drill and extract the material.
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Geologists wrote in a blog post. “The Atlantis massif offers a rare advantage of access, in that it consists of mantle rock that has been lifted up close to the surface by a very slow seafloor spreading process.”
Geologists have been trying to extract large chunks of Earth’s mantle since 1961, when scientists on the Mohole Project attempted to drill under the Pacific Ocean to reach the Mohorovicice discontinuity, the area where Earth’s crust gives way to its mantle. Unfortunately, the project’s drills only made it 601 feet (183 m) below the sea floor before it foundered and the attempt was called off. After that, a number of subsequent ocean drilling efforts also ended without any success.
This means that studying parts of the Earth’s mantle for evidence of processes as diverse as volcanism and planet Earth. magnetic fieldScientists had to rely on bits of rock thrown up by volcanic eruptions, all of which were changed by their journey to the surface.
Geologists, members of the International Ocean Discovery Program aboard the JOIDES Resolution scientific drilling vessel, embarked on their mission to the Atlantis Massif not because they wanted to extract mantle cores, but because they were looking for the origins of life on Earth. The Massif’s rocks contain olivine, which reacts with water in a process called serpentine to produce hydrogen, an essential food source for microbial life.
However, shortly after May 1, when they anchored their drill in a horizontal crack in the sea floor, researchers extracted a record-breaking core of upper mantle rock that extended more than 3,280 feet.
The rock was mainly peridotite, a coarse igneous rock filled with olivine and pyroxene that is the most common type of rock in the upper mantle. Some signs of rock alteration through interactions with seawater could mean that they are from the lower crust rather than the upper mantle, but the scientists are still searching for deeper samples to put their discovery beyond doubt. Within these rocks is a treasure trove of information that geologists will search to find out more information about the inner workings of the Earth.
“The magnitude of history happening is certainly not lost on our science team, many of whom are seasoned field researchers and believe this will be hugely important data for many future generations of scientists,” the geologists wrote in a blog post.
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