Unprecedented Discovery: Scientists Drill Nearly a Mile Beneath Atlantic Ocean Floor to Find Pieces of Earth’s Rocky Mantle

New campaign, by a deep sea drilling ship named JOIDES DECISIONIt wasn’t technically drilled into the mantle, and the hole isn’t the deepest ever drilled under the ocean floor. Instead, the researchers dug into a special “tectonic window” in the North Atlantic where the drill doesn’t have to tunnel as much as the ground. Here, mantle rock has been pushed closer to the surface as the ocean floor is slowly crumbling on the nearby Mid-Atlantic Ridges.

On May 1, they began digging a hole known as U1601C. Andrew McKeag, the mission’s chief scientist, hopes to make the “hole” shallow because the record for drilling in mantle rock, set in the 1990s, is just one-tenth of a mile. Researchers hope to get enough samples to help explain how chemical reactions between mantle rock and water can give rise to life on our planet. But offshore drilling can be a dicey endeavor — the drill stalls, or the long rock sample found may only be a partial sample.

This time, however, the drill produced tube after tube of dark stone, many of which turned out to be complete.

He kept digging deeper and deeper and deeper and then everyone at the science party was like, “Hey, that’s what we wanted all along. Since 1960, we’ve wanted to get craters this deep in mantle rock. When the team stopped drilling on June 2, the team took rock samples from 4,157 feet below the ocean floor.

“We have fulfilled an ambition that has driven the scientific community for decades,” said McKeag.

Scientists on Earth have been eagerly observing the mission, anticipating a jackpot of data that will open new windows into Earth’s depths and fuel years of research.

said Andrew Fisher, a hydrogeologist at the University of California, Santa Cruz, who advised a graduate student who was on the ship and had been spotted. remote development.

In 1909, Croatian seismologist Andrija Muhorovicic discovered a boundary within the Earth.

Mohorovii monitors how seismic waves generated by earthquakes travel through the Earth, similar to using X-rays to probe the inside of the human body. Near the surface, seismic waves travel at a single speed, but after passing through certain areas around the world, they travel more rapidly, suggesting that the waves travel through two distinct layers of rock.

This discontinuity, called moho, is now known as The line between the Earth’s crust and the mantle. The depth varies, but the mantle generally begins about five miles beneath the ocean floor and about 20 miles beneath the continents.

said Jessica Warren, professor of geosciences at the University of Delaware who also monitors the Progress Telemetry Project. “If we want to understand the Earth in its entirety, there are enormous rocks beneath it.”

The Earth’s inner core appears to be slowing its rotation

Mantle is not fully known. Occasionally, volcanic eruptions spew out chunks—greenish chunks of peridot, the type of rock that predominates in the upper mantle, embedded in basaltic rock. But this sample, so called xenolit mantelHowever, it has limitations, having been frequently chewed and hollowed out since its journey to the surface. There is also ophiolite, which is colored sheets of oceanic crust with some of the upper mantle that has been uplifted and glued to Earth. But the journey has also changed.

What scientists have long missed are samples of petrified mantle rock. Project Moholea famous oceanic expedition, set out to drill through the thin crust on the ocean floor to reach the mantle in 1961 but failed.

The part of the ocean floor where the mantle is closest to the surface looks like an opportunity to sample without the technical difficulty of drilling through miles of crust. It’s here that the scientists at JOIDES Resolution set their sights on one of the ship’s previous final missions scheduled retirement In the 2024 fiscal year.

The team left Ponta Delgada in Portugal’s Azores in April and headed to the Atlantis Massif, an underwater mountain the size of Mount Rainier. Its primary mission is not to drill the deepest holes in mantle rock, but to sample the rock for clues about how, in the absence of life on Earth, tiny organic molecules form when rock interacts with water.

“This could be a way that you can go beyond just getting to water and rocks,” said Susan Lang, expedition chief scientist and scientist at the Woods Hole Oceanographic Institution. generate hydrogen, [and] That hydrogen is a really great fuel for things like making smaller organic molecules, and then being able to combine with other organic molecules and lead to early life.”

The bedrock extracted from crater U1601C is dominated by peridotite, which is the most common rock type found in the upper mantle. the sample It’s changed by exposure to seawater, scientists say We have already started discussing how to interpret the results.

Much of the mantle is buried beneath the Earth’s crust, not exposed to the ocean as at this site. This raises a fundamental question: How well does the latest sample mimic the rest of the mantle? Do rock Does it really represent the mantle, or not the crust?

In this case, is the mantle-crust boundary sharp, or a more gradual transition? The sample is not pure peridotite, and this could be a key clue.

“It’s kind of fragmentation, but maybe it’s the lower crust,” said Fisher, listing the various rock types reported in the Science Daily Annals. “This is really unusual – more than a kilometer of highly altered lower crust and/or upper mantle rock. I think it’s a mix.”

Scientists are so busy processing the volume of rock they have recovered that they have not had the opportunity to study the samples in detail, or even consider the scale of the achievement. Drill bits need to be replaced every 50 hours. The team on board worked 12-hour shifts, without losing a minute.

One morning, Lang became distracted and excused himself from the interview when he saw seawater splashing through the window.

“I saw this seawater stage, which is always a really interesting point where they separate this thing from seawater jets all over the place,” Lang said. “Normally, this is my warning that a nucleus will arrive on deck in the next five minutes.”

What excites them all is the hope that deeper samples will yield “fresher” rock, less altered by other processes and closer to what forms the mantle.

“The deeper we go down there, the closer we see what the rocks look like, the closer to what the mantle looks like,” Warren said.