A crescent-shaped crater in northeastern China holds the record for the largest impact crater on Earth, formed in the past 100,000 years.
Before 2020, the only other impact crater discovered in China was found in Xiuyan County, coastal Liaoning Province, according to a statement from the NASA Earth Observatory.
Then, in July 2021, scientists confirmed that a geological structure in the Lesser Xingan mountain range was formed as a result of the collision of a space rock. a land. The team published a description of the newly discovered impact crater that month in the journal Meteorites and planetary sciences.
Yilan crater is about 1.15 miles (1.85 km) wide and likely formed about 46,000 to 53,000 years ago, based on radiocarbon of coal and organic lake sediments from the site, says a NASA statement.
The researchers collected these sediment samples by extracting a drill core from the center of the crater, Forbes reported.
Underneath more than 328 feet (100 meters) of layered lake and swamp sediments, the team found a slab about 1,000 feet (320 meters) thick of fractured granite, a granite composed of many rock fragments held together in an array. . This rock bears telltale scars that it was hit by a meteor.
For example, rock fragments show signs of melting and recrystallization during impact, as the granite rapidly heats up and then cools. Other fragments of the rock survived this melting process and instead contain “shocked” quartz that shattered in a distinct pattern when the space rock crashed, according to Forbes.
The team also discovered teardrop-shaped glass shards and pieces of glass punched with tiny holes created by gas bubbles. These two features also indicate that a high-intensity impact occurred there, according to a NASA statement.
Part of the southern edge of Yilan Crater is missing, so the geological structure looks like a crescent from the top, Global Times reported. Chen Ming, one of the article’s authors and a research fellow from the Guangzhou Institute of Geochemistry, told the Global Times that such crescent-shaped craters are relatively rare on Earth.
In October 2021, the Landsat 8 satellite captured a stunning snapshot of the crater’s northern edge, and scientists are now investigating how and when the southern rim disappeared, according to a NASA statement.
The so-called meteorite crater in Arizona held the record for the largest impact crater less than 100,000 years old; It is about 49,000 to 50,000 years old and has a diameter of 0.75 miles (1.2 km). By comparison, the Xiuyan crater is 1.1 miles (1.8 km) wide, but its age is unknown, Forbes reports.
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