Earth and Mars -- distinct inner Solar System products
arXiv:2006.11051 · doi:10.1016/j.chemer.2021.125746
Abstract
Composition of terrestrial planets records planetary accretion, core-mantle and crust-mantle differentiation, and surface processes. Here we compare the compositional models of Earth and Mars to reveal their characteristics and formation processes. Earth and Mars are equally enriched in refractory elements (1.9 CI), although Earth is more volatile-depleted and less oxidized than Mars. Their chemical compositions were established by nebular fractionation, with negligible contributions from post-accretionary losses of moderately volatile elements. The degree of planetary volatile element depletion might correlate with the abundances of chondrules in the accreted materials, planetary size, and their accretion timescale, which provides insights into composition and origin of Mercury, Venus, the Moon-forming giant impactor, and the proto-Earth. During its formation before and after the nebular disk's lifetime, the Earth likely accreted more chondrules and less matrix-like materials than Mars and chondritic asteroids, establishing its marked volatile depletion. A giant impact of an oxidized, differentiated Mars-like (i.e., composition and mass) body into a volatile-depleted, reduced proto-Earth produced a Moon-forming debris ring with mostly a proto-Earth's mantle composition. Chalcophile and some siderophile elements in the silicate Earth added by the Mars-like impactor were extracted into the core by a sulfide melt. In contrast, the composition of Mars indicates its rapid accretion of lesser amounts of chondrules under nearly uniform oxidizing conditions. Mars' rapid cooling and early loss of its dynamo likely led to the absence of plate tectonics and surface water, and the present-day low surface heat flux. These similarities and differences between the Earth and Mars made the former habitable and the other inhospitable to uninhabitable.
arXiv comment90 pages, 26 figures, 3 tables
References in corpus (27)
- A low mass for Mars from Jupiter's early gas-driven migration
- The origins and concentrations of water, carbon, nitrogen and noble gases on Earth
- Building Terrestrial Planets
- Accretion and differentiation of the terrestrial planets with implications for the compositions of early-formed Solar System bodies and accretion of water
- High-resolution simulations of the final assembly of Earth-like planets 1: terrestrial accretion and dynamics
- The origin of the Moon within a terrestrial synestia
- Oxygen isotopic evidence for vigorous mixing during the Moon-forming Giant Impact
- The Effect of Jupiter's Formation on the Distribution of Refractory Elements and Inclusions in Meteorites
- C2D Spitzer-IRS spectra of disks around T Tauri stars: I. Silicate emission and grain growth
- The composition of Mars
- The formation and evolution of planetary systems: Grain growth and chemical processing of dust in T Tauri systems
- Growing the terrestrial planets from the gradual accumulation of sub-meter sized objects
- Planetary and meteoritic Mg/Si and d30Si variations inherited from solar nebula chemistry
- Highly siderophile elements were stripped from Earth's mantle by iron sulfide segregation
- Near-equilibrium isotope fractionation during planetesimal evaporation
- Polluted White Dwarfs: Constraints on the Origin and Geology of Exoplanetary Material
- Gallium isotopic evidence for extensive volatile loss from the Moon during its formation
- Silica in Protoplanetary Disks
- Chondrule Formation in Bow Shocks around Eccentric Planetary Embryos
- Thulium anomalies and rare earth element patterns in meteorites and Earth: Nebular fractionation and the nugget effect
- Testing the chondrule-rich accretion model for planetary embryos using calcium isotopes
- Earth's chondritic Th/U: negligible fractionation during accretion, core formation, and crust - mantle differentiation
- Subsolar Al/Si and Mg/Si ratios of non-carbonaceous chondrites reveal planetesimal formation during early condensation in the protoplanetary disk
- Constraints on the pre-impact orbits of Solar System giant impactors
- Evidence for post-nebula volatilisation in an exo-planetary body
- Reference Models for Lithospheric Geoneutrino Signal
- Nebular history of an ultrarefractory phase bearing CAI from a reduced type CV chondrite