Located in northeastern China the discovery of the largest impact crater on Earth

Part of the southern edge of Yilan Crater is missing, so the geological structure looks like a crescent from above.

When the Earth, Moon, or other planets are subjected to an "impact event" by meteorites, asteroids, or a large celestial body; This leads to the resulting craters, which are called "impact craters".

One of the most famous collision events is the asteroid impact that led to the "Chicxulub crater" near the town of Chicxulub in the Yucatan Peninsula, Mexico, which occurred about 66 million years ago in the prehistoric period, and led to the extinction of dinosaurs and other creatures on Earth.

But recently, according to a report published by Live Science, the largest impact crater on Earth was discovered, in the Lesser Xingan mountain range, northeastern China, which is in the form of a crescent, and was formed in the past 100,000 years. This crater is called "Yilan crater", after the village near it.

Yilan nozzle

According to the statement issued by the NASA Earth Observatory, the Yilan crater is the second to be discovered in China after the relatively small "Xiuyan crater" that was discovered in the coastal province of Liaoning before 2020. 190 craters are known around the world, according to a report by Forbes magazine.

The scientific team published a study in the journal Meteoritics and Planetary Science.

According to a NASA statement, the discovery of this crater dates back to 2019, and in July 2021, after studying the latest satellite images of the site; The team became more convinced that it was an impact crater.

Based on the analysis of satellite images, the scientists confirmed that a geological structure in the Lesser Xingan Mountains was formed as a result of the collision of a space rock or an asteroid with Earth. As a result of this collision, a crater with a diameter of about 1.85 km was formed.

It likely formed about 46,000 to 53,000 years ago, based on radiocarbon dating of coal deposits and organic lakes from the site.

To study the geological structure of this crater; The researchers collected sediment samples from the center of the crater in order to analyze them and reveal their characteristics.

Sediment samples analysis

According to the Live Science report, the hole filling consists of a successive series of sediments 100 meters thick, and beneath it a layer of broken granite 320 meters thick, which is a granite consisting of many rock fragments fastened together in a matrix. This rock bears scars indicating the impact of the meteorite that hit it.

For example, the rock fragments show signs of melting and recrystallization during the impact, as the granite rapidly heats to more than 1,200 degrees, then cools in situ, consistent with the impact.

Lithographic analyzes of the undissolved granite blocks show the presence of shock minerals such as quartz crystals with a distinctive pattern of parallel, planar cracks, as a result of shock waves that travel through the bedrock.

On the other hand, the results of the analysis showed teardrop-shaped glass fragments, and pieces of glass pierced with small holes resulting from gas bubbles, and these two features also indicate a high-intensity collision there.

Why does the crater look like a crescent?

According to the Global Times, part of the southern edge of the Yilan crater is missing, so the geological structure looks like a crescent from above .

Chen Ming, one of the article's authors and a research fellow from the Guangzhou Institute of Geochemistry, told the newspaper that such crescent-shaped craters are relatively rare on Earth.

The Live Science report adds that in October 2021, the "Landsat 8" satellite captured stunning shots of the northern edge of the crater, which showed the shape of the crescent.

According to a NASA statement, scientists are investigating how and when the southern edge lost its parts, which led to the appearance of this shape.