Before 2020, it was in Xiuyan county of the coastal province of Liaoning that the first impact crater never discovered in China. This information was confirmed in a statement from NASA’s Earth Observatory. Recently, a second impact craterwhich formed over the past 100,000 years, was spotted in the northeast china. He holds the record for largest impact crater on Earth.
This crescent-shaped crater known as Yilan is up to 1.15 miles (1.85 kilometers) in diameter. According to the NASA statement, the giant hole probably formed around 46,000 to 53,000 years ago. This study relied on the basis of dating at radiocarbon charcoal and organic lake sediments of the site.
To collect the sediment samples, the researchers had to extract a drill core at the center of the crater, Forbes reported. More than 100 meters deep below the lake and marsh sediments is a slab approximately 320 meters thick. This one is composed of granite including numerous rock fragments.
The rock bears scars revealing the impact of a meteorite
The traces found on the rock fragments show signs of melting and of recrystallization on impact. This suggests that the granite very quickly warmed up and then cooled down. On the other hand, other fragments were not affected by this merging process and contain “shocked” quartz. The rocky debris shattered showing a distinct pattern when the space rock crashed.
A southern part of the Yilan crater is missing
In addition, the researchers noticed glass shards identical to a drop of water. Note that pieces of glass containing tiny holes created by gas bubbles were also part of their discovery. Both characteristics reveal that a high intensity impact occurred at the location, according to the NASA statement.
The missing part located south of the Yilan crater seems to give it the crescent shape seen from above.
“Such crescent-shaped impact craters are relatively rare on Earth. »
Global Times Chen Ming, one of the authors of the article and a researcher at the Guangzhou Institute of Geochemistry