Lithospheric loading model for large impact basin where mantle plug presents

TL;DR

This paper develops a lithospheric loading model that incorporates mantle uplift structures to better understand the physical properties of planetary lithospheres in impact basin regions, especially on Mars.

Contribution

It introduces a novel mantle uplift structure into the lithospheric loading model, improving analysis of gravity and topography data in impact basin regions.

Findings

Inferred elastic thickness of the Martian lithosphere at impact basins.

Demonstrated the importance of mantle uplift in modeling gravity anomalies.

Applied the model to Argyre and Isidis basins using InSight data.

Abstract

Lithosphere is an outer rigid part of the terrestrial body, usually consisting of the crust and part of the mantle. Characterizing the physical properties of the lithosphere is critical in investigating its evolution. By modeling mass-related loads within the lithosphere, physical parameters such as the elastic thickness of the lithosphere can be inferred from gravity and topography data. In the impact basin region, however, the low topography-gravity correlation and the sharp change in admittance from negative to positive within a narrow spheric harmonic degree make this model inapplicable. In this work, we incorporated mantle uplift structures commonly formed in impact basin regions into the lithospheric loading model. The crustal-mantle boundary of this mantle uplift structure is inferred from the global crustal thickness model. The gravity anomaly of the deflected lithosphere is calculated at the surface and crustal-mantle boundary, then the theoretical gravity admittance and correlation can be compared with the observed data. We sampled parameters using this mantle loading model at Argyre and Isidis basin on Mars with a novel crustal thickness model from the InSight mission. Our work suggests that proper modelling of the impact-induced load is critical to understanding the physical properties of the planetary lithosphere in the basin region.