In 2021, a crater formed by a meteorite impact was discovered in Iran County, Harbin City, Heilongjiang Province, China, not far from the Korean Peninsula. This marks the second time a meteorite crater has been found in China since the Shuyuan crater in Liaoning Province. The number of meteorite craters discovered in Northeast Asia has reached three, including these two craters and the crater identified in Hapcheon, Gyeongnam Province, in 2020. The process of crater formation is still largely shrouded in mystery. Scientists from China, Italy, and the United States found that the meteorite that fell in Iran County was among the most powerful to strike Earth in the last 80,000 years.
Researchers from the Chinese Academy of Sciences, the University of Danunzio in Italy, and the Georgia Institute of Technology in the United States introduced their analysis results of the three-dimensional structure and impact process of the Iranian meteorite crater in the journal Communications Earth & Environment on the 17th (local time).
Crater formations created when small asteroids or meteoroids collide with Earth form fascinating geological features that encapsulate the mysteries of the solar system and Earth's birth, capturing the interest of scientists and the public alike. To date, there have been 207 reported craters worldwide, and there are 43 sites with evidence of asteroid impacts.
Craters provide a natural environment to study the process of rock and mineral formation under ultra-high temperature and pressure deep within the Earth. It is not easy to obtain samples from rocks deep in the mantle. However, the extreme temperatures and pressures generated when asteroids or meteoroids collide can instantaneously create minerals similar to those found deep in the mantle. It also provides the opportunity to research the effects of the impact on the organisms and ecological environments that existed at the time.
The Iranian crater was first reported to the academic community in 2020. Until then, the only previously discovered crater in China was in Liaoning Province. Local residents initially did not know the crater was formed by an impact but referred to this sunken crater early on as Chuisan (round mountain range). This crater has a diameter of 1.85 km, making it the largest crater formed in the last 80,000 years. The research team confirmed that the crater formed between 53,000 and 46,000 years ago by measuring the carbon dating of charcoal and lake sediments found in the area. In contrast, the Barringer crater found in Arizona, United States, is estimated to have formed 50,000 years ago but is smaller, with a diameter of 1.2 km, than the Iranian crater.
The crater has a crescent-shaped bowl structure. The northern edge is well preserved, rising about 150 m from the floor, while the southern third of the crater has disappeared. This appearance is also well depicted in satellite images. Photos taken of the northern edge slope in autumn show vibrant fall foliage. However, the characteristics of the impact process and the underground structure remained a mystery until recently.
The research team installed seismometers at 220 points within the crater to study the underground structure. They used an analytical technique called passive source imaging, based on a high-density seismometer array. The researchers identified a circular crater formed by meteorite sediment and rocks created during the impact. They also clearly identified a three-dimensional bowl-shaped structure at depths of 275 to 315 m below the crater.
The research team also estimated the impact velocity and diameter of the meteorite at the time the crater was formed. The analysis showed that the impact energy when the crater formed was approximately 24 megatons (Mt), equivalent to 1,600 times the atomic bomb "Little Boy" dropped on Hiroshima, Japan, in 1945. This is comparable to an energy equivalent to a magnitude 5.5 earthquake. The research team estimated that it is likely one of the largest impact events to occur in the last 80,000 years compared to other craters formed during this period.
Fossils of large mammals, such as mammoths, have been found in the area since 48,000 years ago. It is presumed that many of these mammals lived in the impact area. The drill samples also contained charcoal fragments supporting the notion that the area was once lush vegetation. This indicates that the ecosystem at the time was suitable for large mammals. The research team hypothesized that the meteorite impact likely had a significant impact on the ecosystem at the time.
The meteorite collided relatively recently, but the granite it struck was formed much earlier, around 200 million years ago during the Early Jurassic period. Researchers from the Chinese Academy of Sciences and the University of Vienna in Austria reported that their 2021 drilling results of the crater's center, 438 m deep, revealed ancient lake sediments and fragmented granite hundreds of meters deep. They reported finding definitive evidence that this structure is indeed a meteorite impact crater. Shocked quartz, melted granite, quartz with bubbles, and teardrop-shaped glass fragments were discovered, all indicating that a powerful meteorite impact event occurred.
The research team is still investigating the cause of the disappearance of the southern edge of the crater. The presence of lake bottom sediments inside the crater suggests that the edges have been maintained for a long time. These sediments formed fertile organic soils. In reality, the southern portion of the crater is covered by agricultural land, while the remaining parts are wetlands and forest swamps.
Meteorite craters have been found in North America, South America, Europe, Africa, and Australia. However, they are very rarely found in East Asia. The first meteorite crater was discovered in Liaoning Province, China, in 2010, and the second crater was discovered in Hapcheon, Gyeongnam Province, in 2020. At that time, the research team revealed that the first meteorite crater on the Korean Peninsula, with a diameter of about 7 km, was created around 50,000 years ago through a 142 m deep drilling core investigation and radiocarbon dating results.
The series of meteorite impacts that occurred in the late Cretaceous period, along with the mass extinction of dinosaurs and the emergence of mammals, remain a mystery in the Korean Peninsula and Northeast Asia. Scientists believe that this study will provide evidence of the environmental impacts of meteorite impacts while also offering important data for detecting other craters.
References
Communications Earth & Environment (2025), DOI: https://doi.org/10.1038/s43247-025-02274-5
Meteoritics & Planetary Science (2021), DOI: https://doi.org/10.1111/maps.13711