Cosmic-Ray Exposure Age and Preatmospheric Size of three Recent Falls (L6)

Smith T. M., Li S., Ranjith P. M., Su F., Gattacceca J., ASTER Team, He H.

82nd Annual Meeting of The Meteoritical Society 2019

PDF abstract

“Over the past months, three L6 chondrites falls have been observed; Mangui from China, Ozerki in Russia, and Viñales in Cuba. The Mangui meteorite fell in the Yunnan Province, China at 9:43 pm on June 1st, 2018 [1]. Based on recent calculations, the meteorite entered Earth’s atmosphere with an angle of 55.3±2.5°, from southeast to northwest, resulting in a strewn field of ~12 km long [2]. Up to now, more than 1000 individuals or fragments have been identified, with masses ranging from 0.04 g to ~1280 g, the total mass being ~50 kg. Mangui has been classified as a L6 ordinary chondrite, with a shock stage S4-S5 [1,2]. The Ozerki meteorite (L6, shock stage S4-S5) fell in Russia on June 21, 2018, 20 days after Mangui. Based on models, the total number of specimens has been estimated to be ~100 individuals, for a total mass of ~7 kg. Search campaigns are still ongoing, and more masses are expected to be found. Finally, the Viñales meteorite (L6, schock stage S3) fell in Cuba on February 1st, 2019. In the following days, several hundred of individuals have been collected by locals. Here we study the cosmic-ray exposure (CRE) history of two individual samples of Mangui, Ozerki, and Viñales by measuring cosmogenic radionuclides and noble gases, produced in space by galactic cosmic rays (GCRs). We are especially interested in the CRE age and the preatmospheric size of the meteoroid, the latter could help to better understand the disruption mechanisms during the atmospheric entry. Based on the short time interval between the different observed falls, similar petrographic types, and the similar shock characteristics, we expect these three meteorites to have a similar exposure history and therefore to be paired. “