^1,2,3,4Sky P. Beard,^2,3Timothy D. Swindle,⁵Thomas J. Lapen,^2,3David A. Kring
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13927]
¹State Key Laboratory in Lunar and Planetary Science, Macau University of Science and Technology, Avenida Wai Long, Macau, Taipa, 999078 P.R. China
²NASA Solar System Exploration Research Virtual Institute, Moffett Field, California, 94035 USA
³Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona, 85721 USA
⁴CNSA Macau Center for Space Exploration and Science, Macau, P.R. China
⁵University of Houston, Houston, Texas, 77004 USA
Published by arrangement with John Wiley & Sons

The LL5 chondrite Chelyabinsk has had numerous isotopic studies since its fall in 2013. These data have been used to suggest ~8 impact events recorded from multiple isotopic systems (e.g., Ar-Ar, U–Pb, Sm-Nd, Rb-Sr, among others). We report details of Ar-Ar and U-Pb results and re-evaluate the geochronology of Chelyabinsk. Argon has the youngest Ar-Ar age recorded in meteorites, 25 ± 11 Ma, and an older resetting event at ~2550 Ma. The U-Pb analysis has an upper concordia age of 4456 ± 23 Ma and a lower concordia age of 184 ± 200 Ma. The lower concordia intercept represents a later thermal event (e.g., an impact), the most recent time that lead loss occurred, and could represent resetting by the youngest event recorded by Ar-Ar. Combining our data with literature results, we find strong evidence of at least four impact events (~4450, 2550, 1700, 25 Ma), with some evidence for two additional impacts (~3700, 1000 Ma).