Mercury's geochronology revised by applying Model Production Functions to Mariner 10 data: geological implications

TL;DR

This study applies Model Production Function (MPF) chronology to Mariner 10 crater data on Mercury, providing revised geological ages that suggest recent volcanic activity and a variable impactor flux over time.

Contribution

It introduces a novel application of MPF models to Mercury's surface, refining age estimates and implications for planetary geological history.

Findings

Caloris interior plains may be as young as 3.59 Ga

Younger ages for Mercury's highlands and basins compared to previous models

Impactor flux varied over time, aligning with MBAs and NEOs

Abstract

Model Production Function chronology uses dynamic models of the Main Belt Asteroids (MBAs) and Near Earth Objects (NEOs) to derive the impactor flux to a target body. This is converted into the crater size-frequency-distribution for a specific planetary surface, and calibrated using the radiometric ages of different regions of the Moon's surface. This new approach has been applied to the crater counts on Mariner 10 images of the highlands and of several large impact basins on Mercury. MPF estimates for the plains show younger ages than those of previous chronologies. Assuming a variable uppermost layering of the Hermean crust, the age of the Caloris interior plains may be as young as 3.59 Ga, in agreement with MESSENGER results that imply that long-term volcanism overcame contractional tectonics. The MPF chronology also suggests a variable projectile flux through time, coherent with the MBAs for ancient periods and then gradually comparable also to the NEOs.