Scientists have found the first evidence that life existed deep within the bedrock of Greenland around 75 million years ago.
This discovery, published in the journal Geochemistry, Geophysics, Geosystems, sheds light on the mysterious world beneath our feet, known as the deep biosphere.
The deep biosphere is a harsh environment far below the Earth’s surface, where sunlight and dissolved oxygen are absent.
Despite these challenging conditions, microorganisms have managed to survive there for millions of years.
However, understanding how long life has existed in this underground world and how widespread it is has been a challenge, mainly because only a few studies have explored this hidden habitat.
In recent research conducted in western Greenland, scientists drilled deep into the bedrock near the ice sheet to uncover clues about ancient life.
At depths of several hundred meters, they found minerals lining the cracks in the bedrock. These minerals act like time capsules, preserving important chemical evidence of life from millions of years ago.
Henrik Drake, an Associate Professor at Linnaeus University in Sweden and the lead author of the study, explained how they used a technique called high-resolution geochronology to date these minerals.
This method involves analyzing how much uranium in the minerals has decayed into lead, giving scientists an estimate of their age. The results showed that the minerals were formed between 64 and 75 million years ago.
Interestingly, this time period overlaps with significant tectonic events, specifically the early stages of the opening of the Atlantic Ocean and the Labrador Sea.
These events likely created deep cracks in the bedrock of western Greenland, allowing microorganisms, such as sulfate-reducing bacteria, to colonize the newly formed spaces.
Drake described these findings as “chemical fingerprints” that point to the presence of life in this extreme environment. In addition to the chemical evidence, the researchers also discovered biological traces, specifically bacterial fatty acids, preserved inside calcium carbonate crystals found in the bedrock fractures.
To further support their findings, the team analyzed different sulfur isotopes in the minerals. These analyses confirmed that the minerals were formed by bacteria, providing strong evidence that life existed deep within Greenland’s bedrock millions of years ago.
This groundbreaking discovery not only offers a glimpse into ancient life on Earth but also helps scientists understand how life can survive in extreme environments. The deep biosphere is still largely unexplored, but with each new discovery, we come closer to unraveling the mysteries of life beneath the Earth’s surface.
