Martian surface dating model refinement based on Chang'E-5 updated lunar chronology function

Abstract

Planetary surface ages are extremely important to geologic evolution studies. For extraterrestrial bodies, the crater size-frequency distribution dating method, including a crater production function and a chronology function, was established based on the radiometric ages of Apollo and Luna samples from the Moon. Recently, the radiometric age of a sample from Chang'e-5 mission added a data point where there was previously a gap in sample ages, and an updated lunar chronology function was proposed. This research aims to recalculate the Martian surface dating model from the newly updated lunar chronology function. The calculation takes account of the differences in impact rates, impact velocities, surface gravities, the threshold diameters of craters' transition from the strength to gravity regime and from simple to complex crater structures on the Moon and Mars. We use the Neukum production function, although other production functions could also be implemented with our method. A series of Martian isochrons is derived, and an approximated analytical form production function is provided for convenient applications in future studies. The Martian chronology function is finally obtained through fitting crater frequencies larger than 1.0 km in diameter with the corresponding ages of the isochrons. The resultant Martian PF and CF in this research are largely comparable with previous results. Based on the refined lunar chronology function, our model will enhance the reliability of the estimating Martian surface ages and we suggest it be used in future studies.