Japan Geoscience Union Meeting 2021

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[J] Oral

S (Solid Earth Sciences ) » S-GL Geology

[S-GL22] Geochronology and Isotope Geology

Fri. Jun 4, 2021 1:45 PM - 3:15 PM Ch.23 (Zoom Room 23)

convener:Takahiro Tagami(Graduate School of Science, Kyoto University), Yuji Sano(Division of Ocean and Earth Systems, Atmosphere and Ocean Research Institute, University of Tokyo), Chairperson:Takahiro Tagami(Graduate School of Science, Kyoto University), Yuji Sano(Center for Advanced Marine Core Research, Kochi University)

2:30 PM - 2:45 PM

[SGL22-03] Asteroid shower on the Earth-Moon system 0.8 billion years ago

*Kentaro Terada1, Tomokatsu Morota2, Mami Kato3 (1.Department of Earth and Space Science, Graduate School of Science, Osaka University, 2.Graduate School of Science, The University of Tokyo, 3.MEISEI ELECTRIC CO., LTD)

Keywords:Crater Chronology, impact flux, Earth and Moon system, Lunar Orbiter KAGUYA

We investigate the formation ages of 59 lunar craters with fresh morphologies and diameters greater than approximately 20 km and first find that 8-17 of 59 craters were formed simultaneously. Considering the radiometric ages of ejecta from Copernicus crater and impact glass spherules from various Apollo landing sites, we conclude that sporadic meteoroid bombardment occurred across the whole Moon at approximately 0.8 Ga. Based on crater scaling laws and collision probabilities with the Earth and Moon, we suggest that at least (4–5) × 10^16 kg of meteoroids, approximately 30–60 times more than the Chicxulub impact, must have plunged into the Earth.