Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Planetary and Space Science art. 104755 [11 p.] Impact craters Mars Impact rate Layered ejecta craters 2020 fdi:010077879 ENG Planetary and Space Science 0032-0633 ISI:000510110900002 10.1016/j.pss.2019.104755 https://www.documentation.ird.fr/hor/fdi:010077879 https://www.documentation.ird.fr/intranet/publi/2020/02/010077879.pdf 180 Horizon (IRD) Ages of geological units of planetary bodies are determined from impact crater counts on their surface. These ages are model-dependent, and several models largely used in the community assume a constant production function and a constant cratering rate over the last 3 Ga. We have mapped the population of small impact craters (>200 m in diameter) formed over a population of large impact craters (>5 km in diameter) with layered ejecta on Acidalia Planitia, Mars. We have deduced the age of each large impact crater under the assumption of a constant impact rate and constant production function. The impact rate inferred from this set of ages is, however, not constant and show a significant increasing during the last similar to 1 Ga compared to chronology models commonly used. We interpret this inconsistency as an evidence for temporal variations in the size-frequency distribution (SFD) of impactors in the main belt, consistent with recent studies argued for a late increasing of the large impactor flux on Earth and the Moon. 060 ; 020 UR234