Compositional Layering in Io Driven by Magmatic Segregation and Volcanism

Dan C Spencer,David A May,Laszlo P Keszthelyi,Ian J Hewitt,Richard F Katz

doi:10.1029/2020je006604

Abstract

AbstractThe compositional evolution of volcanic bodies like Io is not well understood. Magmatic segregation and volcanic eruptions transport tidal heat from Io's interior to its surface. Several observed eruptions appear to be extremely high temperature (≥1600 K), suggesting either very high degrees of melting, refractory source regions, or intensive viscous heating on ascent. To address this ambiguity, we develop a model that couples crust and mantle dynamics to a simple compositional system. We analyze the model to investigate chemical structure and evolution. We demonstrate that magmatic segregation and volcanic eruptions lead to stratification 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 stratification.

Highlights

Jupiter's moon Io is the most volcanically active body in the solar system
We demonstrate that magmatic segregation and volcanic eruptions lead to stratification of the mantle, the extent of which depends on how high temperature melts from the more refractory lower mantle can migrate upwards
This division is on the basis of the transport of refractory melts that form in the lower mantle, which is controlled by the value of the mantle emplacement constant hM

Summary

Introduction

Its volcanism is a result of tidal heating from its mean motion resonance with Europa and Ganymede, which causes widespread melting in its interior (O'Reilly & Davies, 1981; Peale et al, 1979). The export of this tidal heat through the crust by a volcanic system is a process commonly referred to as “heat-piping” (O'Reilly & Davies, 1981). To keep pace with recent improvements in observational techniques (e.g., Davies et al, 2016, 2017; de Kleer, de Pater, et al, 2019; de Kleer, Nimmo & Kite, 2019), interior evolution models that are predictive of eruption temperatures and compositions are increasingly required

Results

Discussion

Conclusion