Oxygen Isotope Exchange Between Molten Silicate Spherules and Ambient Water Vapor with Nonzero Relative Velocity: Implication for Chondrule Formation Environment

TL;DR

This paper develops a theoretical model for oxygen isotope exchange between molten silicate spherules and water vapor with relative motion, revealing mass-dependent fractionation and implications for chondrule formation environments.

Contribution

It introduces a novel model accounting for nonzero relative velocity in isotope exchange, explaining isotope fractionation during chondrule formation.

Findings

Mass-dependent isotope fractionation occurs with moving vapor.

Relative velocity during chondrule crystallization is likely below several 100 m/s.

Model helps interpret oxygen isotope compositions in chondrules.

Abstract

Oxygen isotope compositions of chondrules reflect the environment of chondrule formation and its spatial and temporal variations. Here, we present a theoretical model of oxygen isotope exchange reaction between molten silicate spherules and ambient water vapor with finite relative velocity. We found a new phenomenon, that is, mass-dependent fractionation caused by isotope exchange with ambient vapor moving with nonzero relative velocity. We also discussed the plausible condition for chondrule formation from the point of view of oxygen isotope compositions. Our findings indicate that the relative velocity between chondrules and ambient vapor would be lower than several 100 m/s when chondrules crystallized.