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Beneath cold, high-pressure oceans, water and gas molecules clump together into crystalline solids called gas hydrates. During a research cruise around the North Pole, scientists discovered the deepest gas hydrate ever discovered: an elusive fissure in the seafloor harboring myriad scientific treasures.
The Freya Hydrate Mounds lie beneath the Molloy Ridge near Greenland and were discovered in May 2024. Located at a depth of nearly 12,000 feet (3,640 meters), the mounds are the deepest vents of their type ever discovered. Additionally, the team spotted a massive 3,300 meter tall methane flare rising through the water column, another record-breaking sighting.
“We discovered an ultra-deep system that is both geologically dynamic and biologically rich,” Giuliana Panieri, lead author of the study and a geoscientist at Ca’ Foscari University in Italy, said in a statement. statement. “This discovery rewrites the playbook for deep-sea Arctic ecosystems and the carbon cycle.”
An article about the discovery was published on December 17 in Natural communications.
Cool, submerged vents
The recently discovered Freya Hydrate Mounds are cold gas hydrate seeps. Like hydrothermal vents, cold seeps typically appear as cracks on the seafloor that leak hydrocarbon-rich fluids. The two features have some similarities but differ in important ways.
For example, cold seeps, true to their name, are relatively colder and emit oil and methane in addition to hydrocarbons. They are also more durable as hydrothermal vents, which are generally volatile and short-lived because they are formed by volcanic activity.
Theoretically, there is no depth limit to how deep a cold seep can maintain stability. However, before Freya, researchers had not found any seeps deeper than about 6,500 feet (2,000 meters). So, at a “staggering depth” of about 12,000 feet, the Freya mounds “challenge our previous understanding of hydrate formation,” the researchers said.
No sun, no problem
Because the cold seeps persist for a long time, a rich array of sea creatures make their home near the fissure. As a result, the researchers identified chemosynthetic communities – tiny creatures that live on chemicals, not sunlight – that thrive near the cold seep, such as tube worms, snails and amphipods.
Surprisingly, many creatures living near cold seeps were biologically linked to those residing near hydrothermal ventsthe researchers noted. This link will be essential to consider when developing future conservation plans, they added.
An “ultra-deep natural laboratory”
But that wasn’t all. When the team analyzed the thermogenic gas and crude oil located near the fissure, they found that the soil most likely came from the Miocene, so about 5 to 23 million years ago. But to date, the mounds “appear to form, destabilize and collapse over time,” the researchers said.
“These are not static repositories,” Panieri said. “They are living geological features, responding to tectonics, deep heat flows and environmental changes. »
This dynamic sequence makes the region an “ultra-deep natural laboratory” for studying the interplay between geology and biology in the Arctic – a critical, threatened, but poorly understood part of the planet, they concluded.
