Scientists studying an ancient asteroid crater on the Korean Peninsula have uncovered rock formations that may offer clues to the rise of atmospheric oxygen on Earth.
Researchers from the Korea Institute of Geoscience and Mineral Resources (KIGAM) discovered stromatolites inside the Hapcheon impact crater, the only confirmed asteroid impact site in South Korea. Similar stromatolite fossils represent some of the oldest known evidence of life on Earth.
Their findings were published in Communications Earth & Environment, and the discovery suggests that asteroid impacts, often linked to mass extinctions, may also have supported the development of early oxygen-producing life.
The Importance of Stromatolites
Stromatolites are layered rocks made by microorganisms, such as cyanobacteria, which produce oxygen through photosynthesis. Fossilized stromatolites are at least 3.5 billion years old and are some of the earliest evidence of life on Earth.
Scientists think these microbes were central to the Great Oxidation Event, which occurred about 2.4 billion years ago and led to a lasting increase in atmospheric oxygen levels. Learning where and how early stromatolites lived could help explain how Earth became habitable.
The KIGAM team discovered several stromatolites in the northwestern part of the Hapcheon crater, each measuring about 10 to 20 centimeters across. This is the first time that these types of formations have been found at this location.
Life from the Crater
The team suggests that the stromatolites developed in a hydrothermal lake that formed after the asteroid impact. The impact generated enough heat to melt surrounding rock and keep the water warm and rich in minerals for an extended period. These conditions would have supported the growth of early microbial communities.
Geochemical analysis supports this explanation. The stromatolites contain material from both the asteroid and local rock, in addition to signs of changes caused by heat and water. The inner layers show the most evidence of hydrothermal activity, suggesting they formed when the lake was hottest and continued to grow as it cooled. The combination of heat, minerals, and chemical energy found in hydrothermal environments is favorable for microbial life.
Radiocarbon dating of charcoal in the impact breccia shows that the Hapcheon impact occurred about 42,300 years ago. This is much more recent than the geological events usually linked to early life. The researchers frame the crater as a local example of a post-impact environment that was likely common during Earth’s early history.
“This is the first comprehensive evidence suggesting that stromatolites could form in hydrothermal lakes created by asteroid impacts,” said lead author of the study Dr. Jaesoo Lim. “Such environments may have provided favorable conditions for early microbial ecosystems.”
Oxygen Oases Before Atmospheric Oxygen
The implications may extend far beyond a single crater. During Earth’s early history, asteroid impacts occurred far more frequently. If each impact produced a warm, mineral-rich lake where oxygen-producing microbes could flourish, then these craters may have served as isolated ‘oxygen oases’ long before the atmosphere as a whole became oxygen-rich.
The researchers suggest these localized pockets of biological activity could have contributed to the gradual buildup that eventually triggered the Great Oxidation Event.
Implications for Martian Life
This new research builds on a 2021 study in Gondwana Research, where KIGAM scientists first confirmed that the Hapcheon crater was formed by an impact. This new study adds a biological perspective, linking the physical effects of the asteroid impact to the development of life.
The research may also apply to life on Mars. The early Martian environment contained water-filled impact craters similar to those on ancient Earth. The researchers suggest that Martian craters could be good places to search for signs of past microbial life. This study now provides a model for what this type of evidence might look like.
Austin Burgess is a writer and researcher with a background in sales, marketing, and data analytics. He holds an MBA, a Bachelor of Science in Business Administration, and a data analytics certification. His work focuses on breaking scientific developments, with an emphasis on emerging biology, cognitive neuroscience, and archaeological discoveries.