my country has discovered a rare crescent-shaped crater system caused by the largest collision in nearly 100,000 years
Recently, Chinese scientists discovered a peculiar crater in Yilan County, Harbin City, Heilongjiang Province-Yilan Crater, which is a crescent-shaped crater. This is the second confirmed crater in my country after the Xiuyan crater.
“The planetary impact event that led to the formation of the crater occurred about 49,000 years ago. Based on the analysis of existing crater data, the Yilan planetary collision event is the largest impact event that has occurred on Earth in the past 100,000 years.”8 On the 10th, Chen Ming, a researcher at the Guangzhou Institute of Geochemistry, Chinese Academy of Sciences (hereinafter referred to as the Institute of Geochemistry), revealed in an interview with a reporter from Science and Technology Daily that the cover article of the international journal Meteorite and Planetary Science recently published a paper on the discovery of the Yilan Crater. . The paper was co-written by scientists from the Institute of Geochemistry and the University of Vienna, Austria, with Chen Ming as the first author.
Explore the evolution of the planet from the crater
The discoveries of the first and second meteor craters in my country were all made by Chen Ming.
A crater is an annular crater formed by a small celestial body such as asteroids, comets, and meteoroids hitting the surface of a solid planet. “Collision between planets is the most common natural phenomenon. It has not been interrupted in the past, and it may happen again in the future.” Chen Ming said that by studying craters and exploring the collisions between planets, it can be used to study the formation and formation of planets in the solar system. The evolution process provides valuable information.
In fact, the potential risk of an asteroid hitting the Earth is not non-existent. In February 2013, a meteorite exploded over Chelyabinsk, Russia. The shock wave shattered countless glass and injured thousands of people. After that, the United Nations approved the asteroid defense plan proposed by several astronauts. Other countries have also taken action in this regard. In April of this year, at the opening ceremony of China Space Day 2021, China National Space Administration Director Zhang Kejian revealed that China’s aerospace will demonstrate the construction of a near-Earth asteroid defense system in the future.
“The disasters caused by large-scale planetary impacts are too great. If we can fully understand the major environmental changes and catastrophes caused by such impacts in the past, as well as the impacts of human activities, from the traces left by the impacts-craters. The impact can provide relevant scientific basis for the asteroid defense system.” Chen Ming said.
The formation of the Yilan Crater discovered this time is related to the super-high-velocity impact of an asteroid about 100 meters in diameter.
The planetary impact event was 49,000 years ago
The morphological characteristics of Yilan Crater are very rare, showing as a crescent-shaped crater. This bowl-shaped impact crater is located on a granite body, with a diameter of 1,850 meters, and the rim of the crater is 150 meters above the surface. Most of the crater rim is well preserved, but the southern crater, which accounts for about one-third of the total length, is missing.
“The study revealed that the true depth of the crater reached 579 meters. The bottom of the crater was filled with thick layers of granite fragments, and the upper part of the bottom of the crater was covered with thick layers of lacustrine sediments. The planetary impact event that led to the formation of the crater occurred at a distance from This is 49,000 years ago.” Chen Ming introduced that this was an extremely high-intensity impact event. This asteroid with a diameter of about 100 meters hit the surface at a super high speed, and the energy released by the collision of the planet exceeded the explosive equivalent of 10 million tons of TNT explosives, triggering a powerful explosion.
Studies have shown that the impact shock wave instantly tore a granite body with a volume of more than 400 million cubic meters below the surface into pieces and excavated a huge bowl-shaped crater. The ratio of the true depth to the diameter of the formed crater reached the same type of meteorite on the earth. The most pit. The granite fragments that are hundreds of meters thick at the bottom of the crater are mostly composed of millimeter-level debris. The high degree of rock fragmentation is extremely rare in earth craters.
“Based on the analysis of existing crater data, the Yilan planet collision event is the largest impact event that has occurred on the earth in the past 100,000 years.” Chen Ming said that this collision event occurred in the mid-late Paleolithic period. During the period, the central and southern regions of Heilongjiang were lush grasslands, densely forested, and prosperous animals. There were traces of human activities in the area at that time, and the mammoth-hairy rhino group was also a very active mammal group at that time. “The huge explosion caused by this planetary impact obviously caused the crater and the surrounding area of tens of kilometers. Disaster within the ecological environment”.
After the formation of Yilan Crater, this huge bowl-shaped crater once developed into a lake. During the last glacial maximum, the southern edge of the crater was strongly eroded by glaciers and the lake disappeared.
Provide a “laboratory” for planetary science research
The collision between planets in the universe is a universal natural phenomenon. Many solid planets in the solar system have geological relics left by planetary impacts, that is, craters. At present, many meteorite craters have been discovered on the earth, but such geological relics are very rare in our country.
“my country’s crater research began in the early 1980s. Previously, China has always been a blank on the international crater distribution map.” For many years, Chen Ming has been actively promoting the development of my country’s crater science. In 2009, the discovery of the Xiuyan crater filled the gap in such unique geological structures on Chinese territory. Today, the discovery of Yilan crater has undoubtedly taken China another big step forward in this field, providing a precious “natural crater laboratory” for my country’s planetary science and geological research. (Reporter Ye Qing)
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