Origin of the martian dichotomy and Tharsis from a giant impact causing massive magmatism

The origin of the ancient martian crustal dichotomy and the massive magmatic province of Tharsis remains an open problem. Here, we explore numerically a hypothesis for the origin of these two features involving both exogenic and endogenic processes. We propose a giant impact event during the late stage of planetary formation as the source of the southern highland crust. In a second stage, the extraction of excess heat by vigorous mantle convection on the impacted hemisphere leads to massive magmatism, forming a distinct Tharsis-like volcanic region. By coupling short-term and long-term numerical simulations, we are able to investigate both the early formation as well as the 4.5 Gyr evolution of the martian crust. We demonstrate numerically that this exogenic–endogenic hypothesis is in agreement with observational data from Mars.

► Dichotomous crust forms from early hemispherical magma ocean.
► Tharsis-like magmatic province is formed.
► Volcanism is sustained by low degree convection.