The Chinese scientific research team has, through high-precision chronological studies of Chang'e-6 lunar soil samples, for the first time precisely determined that the Apollo Basin on the Moon formed 4.16 billion years ago. This discovery accurately defines the formation time of the basin and pushes the beginning of the lunar "impact storm" back by at least 100 million years, helping to promote a new understanding of the evolution of the Earth-Moon system. The results were published in the international academic journal Nature Astronomy on the 20th.
According to CCTV News, in this research project, the team led by Academician Xu Yigang from the Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, discovered three special rock fragments ranging from 150 to 350 micrometers in size within 3.5 grams of lunar soil. These fragments are impact melt rocks produced during the formation of the Apollo Basin, making them the ideal "rock clocks" to record the impact event. The team precisely determined the ages of the fragments, and by integrating multisource information such as remote sensing images and geochemical data, ultimately confirmed that the 4.16-billion-year age recorded by the fragments is the formation age of the Apollo Basin.
The surface of the Moon is covered with giant impact basins, most of which are relics of impacts by small celestial bodies in the solar system around 3.8 billion years ago. The scientific community has long debated whether this solar system "impact storm" gradually decreased in intensity or saw a sharp increase between about 4.0 and 3.8 billion years ago.
This decades-long debate has stemmed from a lack of precise age data for key impact basins on the Moon. The Chang'e-6 sampling site is located within the Apollo Basin, itself within the South Pole–Aitken Basin, and is the largest secondary impact structure in the region. Its formation age could signify the onset time of the Moon's late heavy bombardment events.
In summary, this study by the Chinese scientific research team has pushed the starting time of the Moon's "impact storm" back by at least 100 million years; and through analysis, revealed that the intensity of the Moon's "impact storm" declined gradually rather than suddenly surging. This research will help promote a new understanding of the evolution of the Earth-Moon system.