A team of South Korean researchers has discovered evidence that may shed new light on how Earth’s atmosphere first became oxygen-rich, one of the most important turning points in Earth’s history.
Scientists from the Korea Institute of Geosciences and Mineral Resources (KIGAM) discovered stromatolites, layered rock structures created by ancient microbial communities, inside the Hapcheon impact crater. This site is the only asteroid impact crater confirmed on the Korean Peninsula. Their discovery is Communication Earth and EnvironmentNature Portfolio Journal.
Asteroid impact may have created habitat for early life
The researchers say the stromatolites likely formed in hydrothermal lakes that developed after an asteroid impact. The impact would have generated intense heat, melting surrounding rock and warming the water for an extended period of time. These warm, mineral-rich conditions may have provided an ideal environment for ancient microorganisms to survive and grow.
Stromatolites are considered some of the oldest known evidence of life on Earth. These are produced by microorganisms such as cyanobacteria that release oxygen through photosynthesis. Stromatolite fossils date back at least 3.5 billion years.
The research team discovered multiple stromatolites in the northwestern part of the Hapcheon crater. Each structure was approximately 10 to 20 centimeters in diameter. This is the first time that stromatolites have been confirmed at this location.
New clues about Earth’s great oxidation phenomenon
The discovery could also help scientists better understand the Great Oxidation Event (GOE), which occurred about 2.4 billion years ago when oxygen levels in Earth’s atmosphere rose dramatically.
Researchers suggest that hydrothermal lakes formed by asteroid impacts may have served as isolated environments in which oxygen-producing microorganisms could thrive. These crater lakes may have served as local “oxygen oases” before oxygen became widespread on Earth.
Chemical evidence supporting the hydrothermal lake theory
Geochemical examination of the stromatolites revealed signs of both extraterrestrial material and nearby bedrock, as well as evidence that the structure was modified by hydrothermal fluids.
The interior of the stromatolites shows stronger hydrothermal signatures, indicating that they likely formed during an earlier, hotter stage of the crater lake’s history.
Taken together, these findings support the idea that stromatolites developed in hydrothermal lakes created after asteroid impacts and continued to form as the environment gradually cooled.
Possible impact on Mars
This discovery could have implications beyond Earth.
Scientists believe that early Mars once had water-filled impact craters similar to those on ancient Earth. For this reason, researchers say Mars’ impact crater environments could be a promising place to look for signs of past microbial life.
Building on previous research
The new study expands on previous research published in . Gondwana research In 2021, KIGAM scientists confirmed the existence of the Hapcheon impact crater for the first time. The latest research adds to the possibility of biological evidence for stromatolites within the crater environment.
“This is the first comprehensive evidence that stromatolites can form in hydrothermal lakes created by asteroid impacts,” said Dr. Jessu Lim, lead author of the study. “Such an environment may have provided favorable conditions for early microbial ecosystems.”
The Korea Institute of Geoscience and Mineral Resources (KIGAM) is a government-funded research institute focused on earth science, natural resources, and earth system science.
