Compositional layering in Io driven by magmatic segregation and volcanism

TL;DR

This paper presents a coupled crust-mantle model for Io that explains high-temperature eruptions as originating from lower mantle regions, highlighting how magmatic segregation influences planetary differentiation.

Contribution

It introduces a new model linking magmatic segregation and volcanism to compositional differentiation in Io's interior, explaining high-temperature eruptions.

Findings

High-temperature eruptions originate from lower mantle regions.

Magmatic segregation influences mantle differentiation.

Eruptions limit compositional differentiation.

Abstract

Magmatic segregation and volcanic eruptions transport tidal heat from Io's interior to its surface. Several observed eruptions appear to be extremely high temperature ($\geq$ 1600 K), suggesting either very high degrees of melting, refractory source regions, or large amounts of viscous heating on ascent. To address this ambiguity, we develop a model that couples crust and mantle dynamics to a simple compositional system. We analyse the model to investigate chemical structure and evolution. We demonstrate that magmatic segregation and volcanic eruptions lead to differentiation of the mantle, the extent of which depends on how easily high temperature melts from the more refractory lower mantle can migrate upwards. We propose that Io's highest temperature eruptions originate from this lower mantle region, and that such eruptions act to limit the degree of compositional differentiation.