Two extraterrestrial dust horizons found in the Dome Fuji ice core,East Antarctica |
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| Authors: | Keiji Misawa Mika Kohno Takayuki Tomiyama Takaaki Noguchi Tomoki Nakamura Keisuke Nagao Takashi Mikouchi Kunihiko Nishiizumi |
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| Institution: | 1. Antarctic Meteorite Research Center, National Institute of Polar Research, Tokyo 190-8518, Japan;2. Department of Polar Science, The Graduate University for Advanced Studies, Tokyo 190-8518, Japan;3. Polar Meteorology and Glaciology Group, National Institute of Polar Research, Tokyo 190-8518, Japan;4. College of Science, Ibaraki University, Mito 310-8512, Japan;5. Department of Earth and Planetary Sciences, Kyushu University, Fukuoka 812-8581, Japan;6. Laboratory for Earthquake Chemistry, University of Tokyo, Tokyo 113-0033, Japan;7. Department of Earth and Planetary Science, University of Tokyo, Tokyo 113-0033, Japan;8. Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450, USA;1. Silesian University of Technology, Institute of Physics—Center for Science and Education, Konarskiego 22B, 44-100 Gliwice, Poland;2. Department of Climatology, Faculty of Earth Sciences, University of Silesia, B?dzińska 60, 41-200 Sosnowiec, Poland;3. Department of Forest Protection, Entomology and Forest Climatology, University of Agriculture in Krakow, Al. 20 Listopada 46, 31-425 Kraków, Poland;1. Institute of Desert Meteorology, China Meteorological Administration, Key Laboratory of Tree-ring Physical and Chemical Research of China Meteorological Administration, Key Laboratory of Tree-ring Ecology of Xinjiang Uygur Autonomous Region, Urumqi 830002, China;2. Key Laboratory of Western China''s Environmental Systems (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, China;1. Center for Genomic Medicine, Kyoto University Graduate School of Medicine, Shogoinkawaramachi, Sakyo-ku, Kyoto 606-8507, Japan;2. Department of Respiratory Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan;3. Department of Health Informatics, Kyoto University School of Public Health, Kyoto, Japan;4. Department of Medical Ethics and Medical Genetics, Kyoto University School of Public Health, Kyoto, Japan;5. EBM Research Center, Kyoto University Graduate School of Medicine, Kyoto, Japan |
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| Abstract: | Two silicate-rich dust layers were found in the Dome Fuji ice core in East Antarctica, at Marine Isotope Stages 12 and 13. Morphologies, textures, and chemical compositions of constituent particles reveal that they are high-temperature melting products and are of extraterrestrial origin. Because similar layers were found ～ 2000 km east of Dome Fuji, at EPICA (European Project for Ice Coring in Antarctica)-Dome C, particles must have rained down over a wide area 434 and 481 ka. The strewn fields occurred over an area of at least 3 × 106 km2. Chemical compositions of constituent phases and oxygen isotopic composition of olivines suggest that the upper dust layer was produced by a high-temperature interaction between silicate-rich melt and water vapor due to an impact explosion or an aerial burst of a chondritic meteoroid on the inland East Antarctic ice sheet. An estimated total mass of the impactor, on the basis of particle flux and distribution area, is at least 3 × 109 kg. A possible parent material of the lower dust layer is a fragment of friable primitive asteroid or comet. A hypervelocity impact of asteroidal/cometary material on the upper atmosphere and an explosion might have produced aggregates of sub-μm to μm-sized spherules. Total mass of the parent material of the lower layer must exceed 1 × 109 kg. The two extraterrestrial horizons, each a few millimeters in thickness, represent regional or global meteoritic events not identified previously in the Southern Hemisphere. |
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