Early silica crust formation in planetesimals by metastable silica-rich liquid immiscibility or cristobalite crystallisation: the possible origin of silica-rich chondrules.

ABSTRACT: The formation and differentiation processes of planetesimals-small bodies in the solar system-remain actively debated. Planetesimal differentiation is known to have occurred early (<1.5 Myr after the formation of Ca-Al-rich inclusions), as attested by the ages of iron meteorites. Metal-silicate segregation implies global-scale melting, induced by heat released from short-lived radiogenic isotopes, and the consequent generation of a silicate magma ocean. Thermodynamic calculations show that silicate magma crystallisation would have induced silicate-silicate differentiation, leading to the formation of a thick olivine-dominated "mantle" and a thin basaltic "crust". However, thermodynamic modelling of magma ocean crystallisation does not produce any silica phases. Here I experimentally show t

SUBMITTER: Faure F 

PROVIDER: S-EPMC7075931 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature