The influence of deep impact cratering on Martian intraplate faults

Abstract

Martian tectonic structures such as wrinkle ridges and lobate scarps exhibit differences in fault morphology and spacing across the Martian crustal dichotomy. On Earth, inherited structures from ancient tectonic activity may act as primary control in intraplate deformation. This hypothesis is yet to be explored for intraplate settings on other terrestrial planets, such as Mars. Large impact events during the Late Heavy Bombardment may have deeply fractured the Martian crust and mantle-lithosphere creating weakened inherited structures. Here, we hypothesize that Martian fault morphology may be controlled by subsurface deep impact cratering, and test using lithospheric-scale numerical models. In this study, we use the open-source geodynamic code ASPECT (Advanced Solver for Planetary Evolution, Convection, and Tectonics) to investigate the role of impact-related inherited structures on intraplate fault morphology in different lithospheric settings. We present a suite of 2-D numerical lithospheric models under horizontal shortening comparable to that of global contraction. Model parameters are constrained by past Martian modelling efforts and seismic data from the recent InSight mission. However, given the uncertainty in thermal and rheological model parameters for the Martian lithosphere, we extensively test appropriate ranges to analyze their potential role and focus on the lithospheric thickness across the Martian dichotomy. Our modelling results show appropriate faulting at the surface that may be related to Martian wrinkle ridge and lobate scarp morphology and also offer potential subsurface scenarios of deep lithosphere fault networks on Mars. Similar to Earth tectonics, we indicate that deep lithospheric inheritance may provide control over surface fault morphology and spacing, providing new insight into the growth of intraplate faults across the Martian crustal dichotomy.