Scientists uncover the largest crater on Earth under 100,000 years old

The largest impact crater on Earth produced in the last 100,000 years is a crescent-shaped crater in Northeast China.

Prior to 2020, the only other impact crater ever identified in China was discovered in Xiuyan county in the coastal province of Liaoning, according to a NASA Earth Observatory release. Then, in July 2021, scientists determined that a geological structure had evolved in the Lesser Xing’an mountain range as a result of a space rock striking Earth. That month, the researchers described the newly discovered impact crater in the journal Meteoritics and Planetary Science.

According to the NASA statement, the Yilan crater is roughly 1.15 miles (1.85 kilometers) broad and formed between 46,000 and 53,000 years ago, based on radiocarbon dating of charcoal and organic lake sediments from the site. According to Forbes, researchers gathered these sediment samples by extracting a drillcore from the crater’s center.

The researchers discovered a roughly 1,000-foot-thick (320 m) slab of brecciated granite beneath more than 328 feet (100 meters) of layered lake and swamp sediments. Brecciated granite is granite made up of many rocky fragments fused together in a matrix. This rock bears telltale scars of having been struck by a meteorite.

Fragments of the rock, for example, show traces of having melted and recrystallized during the impact, when the granite rapidly heated and then cooled. According to Forbes, other portions of the rock escaped this melting process and instead include “shocked” quartz that shattered in a particular manner as the space rock crashed down.

According to NASA, the crew also found teardrop-shaped glass fragments and glass pieces pierced with tiny holes caused by gas bubbles; both of these traits indicate that a high-intensity impact occurred there.

A portion of the Yilan crater’s southern rim is missing, so the geological structure looks crescent-shaped from above, the Global Times reported. Such crescent-shaped impact craters are relatively unusual on Earth, according to Chen Ming, one of the article’s authors and a research fellow at the Guangzhou Institute of Geochemistry.

According to NASA, the Landsat-8 satellite obtained a stunning image of the crater’s northern rim in October 2021, and scientists are now examining how and when the southern rim vanished.

The Meteor Crater in Arizona formerly held the record for the largest impact crater less than 100,000 years old; it is estimated to be 49,000 to 50,000 years old and is 0.75 miles (1.2 km) in diameter. The Xiuyan crater, by comparison, is 1.1 miles (1.8 kilometers) large, but its age is unclear, Forbes reported.

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