A group of researchers affiliated with several institutions in China and Austria have confirmed that the circular mountain ridge in China's Heilongjiang Province is a crater formed from an asteroid strike.
In their paper published in the journal Meteoritics & Planetary Science, the research team describes their study of craters and what they learned about them. The crater is named Yilan, after the name of a nearby town.
Prior to 2020, the only other impact crater ever discovered was the crater in the Xiuyan area, Liaoning, China. Yilan Crater adds to the list of 190 craters known worldwide.
Quoted from Phys.org, Tuesday (8/3/2022) in 2019, the research team noticed what looked like a crater in the mountains of northeast China. Last year, researchers looked at more recent satellite images of the site and became increasingly convinced that it was a crater. They then made arrangements to study the crater up close. In addition to surveying the crater and the area around it, the team extracted drill cores from its center.
Core studies show that the bottom of the crater is made of lacustrine sediment from an ancient lake that later became a swamp. Beneath it is a 319 meter thick layer of granite breccia along with clastics and granite fragments. This is evidence of bedrock being crushed by a very strong impact.
They also found molten materials such as vesicular glass and water-drop-shaped glass. Both require high temperatures to form as they melt and then cool on the spot. They also found deformation features in other local quartz. Overall, the core features provide strong evidence of an asteroid impact.
The crater is known to be about 1.85 kilometers wide, although its southern rim has faded leaving the crater in the shape of a crescent moon. According to the researchers' records, radiocarbon dating of the area's charcoal and old lake sediments suggests the crater formed about 46,000 to 53,000 years ago.
The record for the crater formed by the impact of the largest celestial body on Earth was previously held by Meteor Crater in Arizona, which is less than 100,000 years old with a diameter of 1.2 km.
This time span suggests that the impact could have been witnessed by early modern humans or other relatives living in the area. The researchers were unable to determine the size of the asteroid that made the crater. Further study is needed to help form a precise estimate.