First finding of impact cratering in the Korean Peninsula
Jaesoo Lim, Sei-Sun Hong, Min Han, Sangheon Yi, Sung Won Kim
Abstract
The 7 km-diameter Jeokjung–Chogye Basin in Hapcheon, southeastern Korean Peninsula, is well-known for its bowl-shaped geomorphology. Here we report the first direct evidence of impact cratering from this basin based our investigations on a 142 m-deep core. The lithological units could be divided into soil-channel sediments (0–6.2 m), lacustrine sediments with fine silt-clayey lamination (6.2–72 m), and impact breccia (72–142 m). We report for the first time, unique impact-driven metamorphic features, including shatter cones at 130 m and planar deformation features (PDFs) in quartz grains from the impact breccia. Based on the radiocarbon dates of charcoals in the lacustrine sediments, we estimate that the impact likely happened during the last glacial period, although further confirmation using other dating techniques is awaited. This relatively young crater provides a rare opportunity to reconstruct high-resolution paleoclimate changes recorded in laminated lacustrine sediments, and to investigate shock metamorphism in a location that experienced significant surficial weathering and erosion under a tropical–temperate climate.