Spatial distribution of isotopes and compositional mixing in the inner protoplanetary disk

Abstract

The mass-independent isotopic signatures of planetary bodies have been widely used to trace the mixing and transport processes in planet formation. The observed isotopic variations among meteorites have been further linked to the modeled mass-weighted mean initial semimajor axes, assuming a spatial isotopic gradient in the inner protoplanetary disk. However, nucleosynthetic isotopic anomalies of nonvolatile elements and mass-independent oxygen isotopic variation (${\Delta }^{17}$O) show different relationships with distance from the Sun. Therefore, it is crucial to know whether isotopes were distributed systematically with heliocentric distance. In this study, we performed N-body simulations on compositional mixing during the collisional accretion and migration of planetary bodies to investigate the spatial distributions of Cr and O isotopes in the inner protoplanetary disk. The modeled mass-weighted mean initial semimajor axes of the parent bodies of noncarbonaceous (NC) meteorites and terrestrial planets were used to calculate the isotopic compositions of these bodies. Our simulations successfully reproduced the observed nucleosynthetic Cr isotopic anomaly among Earth, Mars, and the NC meteorite parent bodies, consistent with a spatial gradient of isotopic anomalies in the inner disk. Asteroids originating from different regions in the inner disk were transported to the main belt in our simulations, resulting in the Cr isotopic anomaly variation of the NC meteorite parent bodies. However, the ${\Delta }^{17}$O distribution among the terrestrial planets and the NC meteorite parent bodies could not be reproduced assuming a ${\Delta }^{17}$O gradient. The absence of a ${\Delta }^{17}$O gradient reflects that the oxygen isotopic mass-independent fractionation might have altered the spatial distribution of the nucleosynthetic ${\Delta }^{17}$O variation before protoplanets formed.

References in corpus (26)

• Solar System evolution from compositional mapping of the asteroid belt
• Building the Terrestrial Planets: Constrained Accretion in the Inner Solar System
• Accretion and differentiation of the terrestrial planets with implications for the compositions of early-formed Solar System bodies and accretion of water
• Equilibration in the Aftermath of the Lunar-Forming Giant Impact
• Bifurcation of planetary building blocks during Solar System formation
• 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
• Mars' Growth Stunted by an Early Giant Planet Instability
• Particle Pile-ups and Planetesimal Formation
• Terrestrial planet formation from lost inner solar system material
• The GENGA Code: Gravitational Encounters in N-body simulations with GPU Acceleration
• Onset of giant planet migration before 4480 million years ago
• Chromium isotopic homogeneity between the Moon, the Earth, and enstatite chondrites
• A primordial origin for the composition similarity between the Earth and the Moon
• Impact splash chondrule formation during planetesimal recycling
• The Feeding Zones of Terrestrial Planets and Insights into Moon Formation
• Terrestrial Planet Formation in a protoplanetary disk with a local mass depletion: A successful scenario for the formation of Mars
• Fingerprints of the protosolar cloud collapse in the Solar System II: Nucleosynthetic anomalies in meteorites
• Growing Mars fast: High-resolution GPU simulations of embryo formation
• The terrestrial planet formation paradox inferred from high-resolution N-body simulations
• Stochasticity & Predictability in Terrestrial Planet Formation
• Isotopically distinct terrestrial planets via local accretion
• Effects of pebble accretion on the growth and composition of planetesimals in the inner Solar System
• Mars' formation can constrain the primordial orbits of the gas giants
• Accretion regions of meteorite parent bodies inferred from a two-endmember isotopic mixing model
• Evidence of a primordial isotopic gradient in the inner region of the solar protoplanetary disc

Cited by in corpus (1)

• Coupling dynamical accretion and chemical differentiation: A unified framework for the diversity of Earth and Mars