A New Chronology for the Moon and Mercury

Abstract

In this paper we present a new method for dating the surface of the Moon, obtained by modeling the incoming flux of impactors and converting it into a size distribution of resulting craters. We compare the results from this model with the standard chronology for the Moon showing their similarities and discrepancies. In particular, we find indications of a non-constant impactor flux in the last 500 Myr and also discuss the implications of our findings for the Late Heavy Bombardment hypothesis. We also show the potential of our model for accurate dating of other inner Solar System bodies, by applying it to Mercury.

Extent, age, and resurfacing history of the northern smooth plains on Mercury from MESSENGER observations

“…This age, $3.8-3.9 Ga for the buried crater population, reflects the oldest period of NSP emplacement. Similar results, albeit with different ages, are obtained with the model production functions of Marchi et al (2009) and Le Feuvre and Wieczorek (2011. When only the population of small buried craters (D = 4-30 km) is considered, N(10) = 47 ± 3 and N(20) = 10 ± 2, and the model age is 3.7 ± 0.01 Ga.…”

“…More recently, two alternative model production functions (MPFs) have been developed that incorporate additional parameters (e.g., modeled relative global impact fluxes, revised crater scaling, two impactor populations, target-specific properties) and newer data (Marchi et al, 2005(Marchi et al, , 2009(Marchi et al, , 2011Le Feuvre and Wieczorek, 2011). The MPF calculated by Marchi et al (2009Marchi et al ( , 2011) results in a model age for the NSP of 2.5 ± 0.3 Ga, and the v 2 test used to assess the MPF fit favors an anchor to intermediate crater sizes (S. Marchi, personal communication, 2012).…”

“…The MPF calculated by Marchi et al (2009Marchi et al ( , 2011) results in a model age for the NSP of 2.5 ± 0.3 Ga, and the v 2 test used to assess the MPF fit favors an anchor to intermediate crater sizes (S. Marchi, personal communication, 2012). The MPF of Le Feuvre and Wieczorek (2011) yields a model age of 3.30 ± 0.3 Ga for the Caloris interior plains, and on the basis of the close similarity of the NSP post-plains crater population to the Caloris interior plains crater population (Fig.…”

Population of Impactors and the Impact Cratering Rate in the Inner Solar System

“…In reality, the projectile created a clearly visible crater, hitting the ground with an impact speed larger than the terminal speed that per square kilometre per year on the Moon, which compares well with the estimate obtained from crater counting on lunar terrains with known ages ((3.3 ± 1.7) × 10 −14 km −2 yr −1 ; Grieve and Shoemaker, 1994). The size-frequency distribution of the lunar craters that is expected from the NEO models using scaling laws matches well the observed crater size frequency distribution for sizes up to 200 km, but is deficient for larger craters by a factor of approximately three to five (Marchi et al, 2009). The reason for this discrepancy is not clear.…”

“…It might be due to inappropriate scaling laws for very large impacts. It may also be due to the fact that most large craters were formed in the distant past, when the cratering rate was higher and the projectile size distribution was different (Strom et al, 2005;Marchi et al, 2009). We address this issue in Section 2.6.…”