Constraining the Origin of Mars via Simulations of Multi-Stage Core Formation

Abstract

It remains an elusive goal to simultaneously model the astrophysics of Solar System accretion while reproducing the mantle chemistry of more than one inner terrestrial planet. Here, we used a multistage core-mantle differentiation model based on Rubie et al. (2011,2015) to track the formation and composition of Earth and Mars in various Grand Tack formation simulations. Prior studies showed that in order to recreate Earth's mantle composition, it must grow first from reduced (Fe-metal rich and O-poor) building blocks and then from increasingly oxidized (FeO rich) material. This accretion chemistry occurs when an oxidation gradient exists across the disk so that the innermost solids are reduced and increasingly oxidized material is found at greater heliocentric distances. For a suite of Grand Tack simulations, we investigated whether Earth and Mars can be simultaneously produced by the same oxidation gradient. Our model did not find an oxidation gradient that simultaneously reproduces the mantle composition of Earth and Mars. Due to its small mass and rapid formation, the formation history of Mars-like planets is very stochastic which decreases the likelihood of compatibility with an Earth-producing oxidation gradient in any given realization. To reconcile the accretion history and ideal chemistry of the Mars-like planet with the oxidation gradient of an Earth-producing disk, we determined where in the Earth-producing disk Mars must have formed. We find that the FeO-rich composition of the Martian mantle requires that Mars' building blocks must originate exterior to 1.0 astronomical units (AU).

20 pages, 7 figures, Accepted for publication at ICARUS 04/2023

References in corpus (9)

• Highly Siderophile Elements in the Earth's Mantle as a Clock for the Moon-forming Impact
• Highly siderophile elements were stripped from Earth's mantle by iron sulfide segregation
• Lunar and Terrestrial Planet Formation in the Grand Tack Scenario
• Growing Mars fast: High-resolution GPU simulations of embryo formation
• A colossal impact enriched Mars' mantle with noble metals
• Metal-silicate partitioning of W and Mo and the role of carbon in controlling their abundances in the Bulk Silicate Earth
• The terrestrial planet formation paradox inferred from high-resolution N-body simulations
• The Effect of Inefficient Accretion on Planetary Differentiation
• Isotopically distinct terrestrial planets via local accretion

Cited by in corpus (2)

• Magnitude of stable iron isotope fractionation limited by multiple stages of terrestrial core formation
• Coupling dynamical accretion and chemical differentiation: A unified framework for the diversity of Earth and Mars