A crater created by an asteroid impact in South Korea has revealed traces of ancient microbial life preserved beneath its surface. The findings point to a scenario where heat from the impact helped maintain a hydrothermal lake, later supporting microbial communities.
The discovery centers on stromatolites, layered mineral structures produced by microbial mats and regarded as some of the oldest evidence of life on Earth. Researchers say the structures formed long after the impact itself but inside environmental conditions created by it.
For decades, scientists have debated whether asteroid impacts merely disrupted Earth’s surface or could they also have created environments where life was able to survive or emerge? The newly studied site adds another example to that discussion. Located in the Jeokjung-Chogye Basin in Hapcheon, the crater was only identified as an impact structure in recent years despite its distinctive bowl-shaped appearance in the landscape.
A Crater With An Unexpected Biological Record
As reported in the research published in Communications Earth & Environment, the basin formed after an asteroid struck the region approximately 42,000 years ago. Previous investigations had already documented signs of meteoritic material mixed with terrestrial rock inside the crater. Researchers also reconstructed the geometry of the impact and determined that the basin once contained a large lake.
The new research targeted sediments beneath the northwestern part of the crater and revealed several stromatolites. Led by geologist Jaesoo Lim of Korea Institute of Geoscience and Mineral Resources (KIGAM), the team identified these layered mineral formations, created by microbial mats and linked to early life on Earth, measured between 10 to 20 centimeters in diameter.
These formations are built gradually as microbial communities trap and bind mineral particles. Comparable structures discovered elsewhere on Earth have been dated to nearly 3.5 billion years ago, making stromatolites one of the most valuable records for understanding ancient biological activity. At this site, researchers concluded the structures were not transported into the crater but formed there.
Mineral Evidence Points To A Hydrothermal Lake
The team examined the chemistry of the stromatolites and surrounding sediment to understand the conditions under which they formed. As explained by the study, one of the strongest indicators came from the presence of europium, an element that becomes markedly more soluble in hot hydrothermal fluids and is commonly interpreted as evidence of hydrothermal processes.
Scientists also documented elevated levels of calcium, calcite, and sulfur in sediments associated with microorganisms adapted to warm environments. These observations support the idea that the crater hosted what researchers describe as a hydrothermal impact lake.
Such systems form when an asteroid impact fractures and heats Earth’s crust. Water filling the basin can remain warm for extended periods as residual underground heat dissipates. Radiocarbon analysis of one stromatolite sample indicated that the structures formed between about 23,400 and 14,600 years ago, suggesting hydrothermal conditions persisted for several tens of thousands of years after the original collision.
A New Piece In The Puzzle Of Early Life
The researchers connect the finding to broader questions surrounding the origin and development of microbial ecosystems. Stromatolites are considered especially valuable because they preserve traces of microbial activity from periods of Earth’s history where direct evidence remains rare.
The researchers say the discovery is the first to strongly suggest that stromatolites formed in hydrothermal lakes created by asteroid impacts.
“This is the first comprehensive evidence suggesting that stromatolites could form in hydrothermal lakes created by asteroid impacts,” said Jaesoo Lim. “Such environments may have provided favorable conditions for early microbial ecosystems.”
The authors noted that the current results do not prove any direct role for stromatolites in Earth’s atmospheric oxygenation. Their work instead points toward the need to investigate additional impact craters on Earth and highlights that similar buried signatures could also exist inside impact structures on Mars.
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