Atlantic Ocean discovery: Scientists uncover hidden source behind Lost City vents, offering clues to life beyond Earth

Scientists have uncovered new evidence explaining the source of energy powering the Lost City hydrothermal field, a unique underwater ecosystem in the Atlantic Ocean. By drilling more than a kilometre beneath the seabed, researchers discovered superheated water with a chemical composition closely matching the fluid emerging from the Lost City's towering white chimneys, suggesting the vents are fed by a hidden reservoir of hot, hydrogen-rich water deep below the ocean floor.

The findings, published in the journal Geochemistry, Geophysics, Geosystems, provide new insights into how life survives in environments without sunlight and could also help scientists understand the potential for life on other worlds.

Discovery sheds light on Lost City's energy source

The Lost City hydrothermal field is one of Earth's most unusual ecosystems. Unlike most environments, life there depends on chemical energy produced when seawater reacts with rocks beneath the ocean floor rather than energy from the Sun.


The site is known for its white carbonate chimneys, which release alkaline fluids rich in hydrogen and methane. These chemicals provide energy for microbes and other organisms living around the vents. Although scientists have long studied these hydrothermal springs, the origin of the energy-rich water feeding them had remained uncertain.

Scientists drill 1.3 kilometres beneath the seabed

As part of the International Ocean Discovery Program's Expedition 399 in 2023, researchers drilled a borehole nearly 1.3 kilometres below the seabed in the Atlantis Massif, an underwater mountain located about 800 metres north of the Lost City hydrothermal field.

The borehole passed through mantle rocks, including peridotite and layers of gabbro, both of which react with seawater over long periods. After drilling, scientists collected water samples from different depths to examine their chemical composition.

Between approximately 675 and 800 metres below the seafloor, researchers found that up to 80 per cent of the water consisted of natural formation water that had circulated through underground rocks rather than being introduced during drilling.

Chemical analysis points to superheated underground water

The water samples contained almost no magnesium but high concentrations of calcium, a chemical signature indicating prolonged interaction between seawater and rocks at very high temperatures.

Scientists also detected elevated levels of lithium, rubidium, cesium and strontium, elements commonly produced during these reactions.

Based on the chemical evidence, the team concluded that the water had interacted with rocks at temperatures of at least 300 degrees Celsius. Although the borehole had cooled by the time samples were collected, its chemical composition showed the water had previously been much hotter.

Researchers found that the chemistry closely matched the fluids flowing from the Lost City's hydrothermal vents.

Study offers clues to early life on Earth

The findings improve scientists' understanding of how chemical energy moves through Earth's crust to sustain life in environments without sunlight.

Hydrogen generated during reactions between water and rocks serves as an important energy source for microorganisms. Researchers believe studying such systems could provide insights into how some of Earth's earliest life forms survived billions of years ago.

Scientists also consider the Lost City one of the closest natural analogues to environments that may exist beneath the icy surfaces of ocean worlds elsewhere in the Solar System. If similar water-rock reactions occur on those worlds, they could generate the chemical energy needed to support microscopic life.

Researchers plan further investigation

The researchers cautioned that the water samples were collected only a few days after drilling and were mixed with seawater, freshwater and drilling fluids. As a result, they cannot yet determine the precise contribution of different rock types to the observed chemistry.

The study also does not establish a direct underground connection between the borehole and the Lost City's hydrothermal chimneys. The research team plans to return after the borehole has stabilised to continue investigating the system.

(With inputs from TOI)