Researchers in China have discovered a well-preserved impact crater in Guangdong Province, dating to the early-to-mid Holocene epoch around 11,700 years ago. The 900-meter-wide Jinlin crater is the largest verified from this period, surpassing Russia's Macha crater. It provides new insights into recent meteorite strikes on Earth.
A team of scientists from Shanghai and Guangzhou has identified the Jinlin crater, a bowl-shaped structure on a hillside in Zhaoqing, Guangdong Province. Protected by a thick layer of weathered granite, the crater measures 900 meters across and is one of only about 200 confirmed impact sites worldwide. Soil erosion measurements suggest it formed during the early-to-mid Holocene, the period beginning at the end of the last ice age roughly 11,700 years ago.
The discovery, detailed in the journal Matter and Radiation at Extremes published by AIP Publishing, reveals that the crater dwarfs other known Holocene impacts, including the 300-meter Macha crater in Russia. "This discovery shows that the scale of impacts of small extraterrestrial objects on the Earth in the Holocene is far greater than previously recorded," said lead author Ming Chen.
Analysis indicates the crater resulted from a meteorite strike, not a comet, which would have created a much larger feature of at least 10 kilometers. The meteorite's composition—whether stone or iron—remains unknown and requires further study. Despite the region's heavy rainfall, strong monsoons, and high humidity, which accelerate erosion, the crater is remarkably intact. Within its granite layers, researchers found quartz grains exhibiting planar deformation features, microscopic structures formed only by shockwaves from celestial impacts.
"On the Earth, the formation of planar deformation features in quartz is only from the intense shockwaves generated by celestial body impacts, and its formation pressure ranges from 10 to 35 gigapascals, which is a shock effect that cannot be produced by any geological process of the Earth itself," Chen explained. These features confirm pressures of 10 to 35 gigapascals during the event.
The Jinlin crater's preservation offers a rare glimpse into Earth's recent impact history. "The impact crater is a true record of Earth's impact history," Chen noted. "The discovery of the Earth impact crater can provide us with a more objective basis for understanding the distribution, geological evolution, and impact history and regulation of small extraterrestrial bodies." Variations in rock types, climate, and erosion across the planet often erase such evidence, making this find particularly significant.