Scientists studying South Korea’s only confirmed impact crater have discovered microbial structures beneath the site that may reveal how asteroid impacts created environments favorable for early life on Earth.

The discovery was made inside the Hapcheon impact crater, also known as the Jeokjung-Chogye Basin, where researchers identified multiple stromatolites. These are layered structures formed by microbial communities and considered among the oldest known traces of life on Earth.

The structures, found in the northwestern part of the crater, measured around 10 to 20 centimeters in diameter and appear to have formed long after the impact itself. Their location and chemistry suggest they developed inside a warm hydrothermal lake created by the asteroid collision.

The findings were reported by researchers from the Korea Institute of Geoscience and Mineral Resources (KIGAM) in Communications Earth & Environment.

Impact heat may have created a microbial refuge

According to the study, the Hapcheon crater formed around 42,000 years ago when an asteroid struck the Korean Peninsula. Previous work had already established that the basin once contained a large lake and preserved evidence of impact-related geological processes.

The new research suggests the collision did more than create a crater. Asteroid impacts can fracture and heat Earth’s crust, creating hydrothermal systems where residual heat warms groundwater and lakes for extended periods. The team proposes that such conditions persisted at Hapcheon, forming a hydrothermal lake capable of supporting microbial ecosystems.

Geochemical analysis supported this interpretation. Researchers found europium enrichment in the stromatolites, an element often associated with hot hydrothermal fluids due to its increased solubility at elevated temperatures. The sediments also contained elevated calcium, calcite, and sulfur signatures linked to microorganisms adapted to warmer environments.

Radiocarbon dating indicated the stromatolites formed between roughly 23,400 and 14,600 years ago, suggesting the hydrothermal lake may have persisted for tens of thousands of years after the impact.

Lead author Jaesoo Lim described the discovery as the first comprehensive evidence suggesting stromatolites could form in hydrothermal lakes created by asteroid impacts.

Possible clues to Earth’s oxygen rise and Mars

The implications extend beyond the crater itself. Stromatolites are among the oldest known records of life, with examples dating back at least 3.5 billion years. Many were built by photosynthetic microbes, such as cyanobacteria, which are believed to have contributed to Earth’s Great Oxidation Event around 2.4 billion years ago.

The researchers suggest impact-generated lakes on the heavily bombarded early Earth may have acted as localized “oxygen oases” where oxygen-producing microbes could survive and expand.

The idea remains interpretive and does not prove stromatolites directly drove atmospheric oxygenation. However, it introduces a possible mechanism linking asteroid impacts, hydrothermal environments, and microbial development. The findings may also influence astrobiology research.

Because early Mars likely hosted crater lakes and impact-driven hydrothermal systems, similar environments could become targets in the search for evidence of ancient Martian life. The team noted that additional impact craters on Earth will need to be studied to determine whether hydrothermal stromatolite systems were more widespread than previously thought.