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Geological Yeon, Hapcheon Hit-Confirmation of rock deformation by impact of a meteorite 200 m in diameter 50,000 years ago
The Jeokjung-chogye Basin in Hapcheon-gun, Gyeongsangnam-do, surrounded by 600m-class mountains, has long been controversial about the origins of its origins, but direct evidence emerged from handshaking meteor collisions . Getty Image Bank
Paleolithic people, who spent the last ice age in Hapcheon-gun, Gyeongsangnam-do 50,000 years ago, may have seen a column of fire rising into the sky with a tremendous impact that they will never forget. Direct evidence appeared through drilling that Hapcheon-gun’s Jeokjung-Gugye Basin was formed by a massive meteorite impact with an estimated diameter of 200 m. The oval-shaped basin, 8 km from east to west and 5 km from north to south, forms a clean crater with the coastal basin (also known as punch ball) in Yanggu-gun, Gangwon-do, and the possibility has been raised meteor collision. In the coastal basin, discriminatory erosion due to differences in rock hardening was accepted as the norm, but the origin of the Hapcheon basin formation was controversial about the origin of the Hapcheon basin formation, such as differential erosion, weathering along the tectonic line and meteorite impact.
Hit a topographic map of the basin on patrol. The asterisk is where the drill core is collected. Provided by the Korean Institute of Geosciences and Mineral Resources
The research team from the Korean Institute of Geosciences and Mineral Resources analyzed the rock columns (drill cores) obtained by drilling 142m deep in the center of this basin in January this year. . In an article published in the recent issue of the scientific journal Gondwana Research, the researchers said: “For the first time on the Korean Peninsula, we present direct evidence of a meteorite impact.” Crater-shaped impact holes created by meteorite impacts have been reported in more than 200 locations around the world. However, in East Asia, this is the second time after the Shuyan crash zone, which is 1.5 km in diameter in Liaoning province, China, announced in 2010, but is much larger.
The appearance of the drilling core. The left is the depth (m). From 142 to 72 m, broken rock fragments were piled up by an explosion, and from 72 to 6.2 m, the sediment layer was finely accumulated in a deep lake, and the upper part was exposed to the outside of the water and then deposited. Provided by the Geological Resources Research Institute
The Geological Resources Research Institute said: “Assuming that the diameter of a meteorite impact hole in the Jeokjung-Guye basin is 4 km (half the size of the basin), it can be seen that a meteor with a diameter of about 200 m has fallen “. “The energy generated at this time is 1400 megatons (It is 100 times the size of the Hiroshima atomic bomb),” he said in a press release. However, the impact of the impact and the aftermath of the impact on the lives of the Paleolithic peoples on the Korean Peninsula and surrounding ecosystems, and how they left traces in the long sediments of lakes on the Korean Peninsula and Japan remained as follow-up research projects. There are two direct evidences of meteorite impacts presented by the One is a conical rock structure formed by shock waves in a 130 m deep shale layer, which is considered representative macroscopic evidence of a meteorite impact.
Conical rock structure, one of the direct evidence of a meteorite impact. It is deformed by high temperature and high pressure at the bottom of the shock hole. Provided by the Institute of Geosciences and Mineral Resources.
The other is a deformed planar structure formed in the process of fusion and re-hardening of quartz mineral particles by a shock wave, and was found at a depth of 142 m, corresponding to the bottom of the impact. These transformations occur at high pressures of 150,000 to 350,000 atmospheres and high temperatures above 2,000 degrees, the researchers said. After the meteorite impact, the Hapcheon Basin was a large lake, revealed in this research. Looking at the drill core, just after the meteor collided and the impact hole formed, a chunk of broken rock was filled to a depth of 70 m, half the depth. Above it, layers of pearls and sand reaching 66 m deep were laid to form a typical lake sediment. The lake, which had been in operation for tens of thousands of years, suddenly disappeared with the opening of the basin. The researchers wrote in the paper: “As a result of carbon dating, the lake’s sedimentary layers accumulated between 30,000 and 63,000 years ago, indicating that the collision was before that time.” Lead author Dr Jaesoo Lim said: “With this study, the Jeonjung-Guage Basin, which remains a mystery in the geological world, has been identified as the first meteorite impact hole on the Korean Peninsula. Articles cited: Gondwana Research, DOI: 10.1016 / j.gr.2020.12.004 By Cho Hong-seop, Staff Reporter [email protected]
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