Moon, Mars, Mercury: Basin formation ages and implications for the maximum surface age and the migration of gaseous planets

摘要

Basin formation ages for Moon, Mars and Mercury are determined by cratering statistics, compared and evaluated with respect to their maximum surface ages and available isotope ages, and two possible Solar System evolution models. Both Mars and Mercury appear to have undergone significant resurfacing, so that at least the first 200-400 million years are not recorded on their surfaces. Basin frequency and crater frequencies below 150 km indicate that the Moon has the oldest surface, Mercury has an intermediate age, and Mars has the youngest preserved terrain. An offset between the basin size-frequency distribution, the smaller crater size-frequency distribution and the main belt asteroid size-frequency distribution is observed in all three cases, suggesting an age difference of about 150 Ma between basin and smaller crater distribution-based ages. I interpreted this in terms of lack of understanding of the basin formation process, and suggest that one possible explanation for the apparently under-representative basin frequency could be a different (lower) average impact velocity compatible with the 'Nice' flux model. The basin formation pattern derived with the standard monotonically decaying or the sawtooth-like Nice-model flux does not reveal a coherent picture according to the late heavy bombardment idea. This is here attributed to an incomplete understanding of the cratering rate ratios between the planetary bodies considered here. Because of the Moon's unique formation history, I also suggest that it is questionable whether the Moon is a suitable analogue for the formation, evolution and cratering record of the other terrestrial bodies. (C) 2014 Elsevier B.V. All rights reserved.