Insights into the nature of plume-ridge interaction and outflux of H2O from the Galápagos Spreading Centre

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Authors

Matthew Lloyd Morgan Gleeson , Sally Gibson 

Abstract

The flow of high-temperature and compositionally-enriched material between mantle plumes and nearby spreading centres influences up to 30% of the global mid-ocean ridge system and represents a significant, but currently unconstrained, flux of volatiles out of the mantle. Here we present new analyses of H2O, F, Cl and S in basaltic glass chips from an archetypal region of plume-ridge interaction, the Galápagos Spreading Centre (GSC). Our dataset includes samples from the eastern GSC, on ridge segments most strongly influenced by the adjacent Galápagos mantle plume, and complements published analyses of volatiles from the western GSC. We use new two-component (peridotite-pyroxenite) forward models of mantle melting to investigate the mechanism of plume-ridge interaction along approx. 1000 km of the GSC. Our results indicate that the observed geochemical and geophysical variations cannot be recreated by models which only involve solid-state transfer of material between the Galápagos mantle plume and the GSC. Instead, we show that the geochemical and geophysical data from the GSC are well-matched by models that incorporate volatile-rich melts formed at high-pressures (>3-4 GPa) in the Galápagos plume stem and transported via channelised flow to the GSC. In addition, our new models demonstrate that channelised flow of enriched, plume-derived melt can account for up to 50% of the H2O outgassed from regions of the GSC which are most strongly influenced by the Galápagos mantle plume.

DOI

https://doi.org/10.31223/X57P5C

Subjects

Earth Sciences, Geochemistry, Other Earth Sciences, Physical Sciences and Mathematics, Volcanology

Keywords

Galapagos, Plume-ridge interaction, Channelised flow

Dates

Published: 2021-02-18 04:24

License

CC BY Attribution 4.0 International

Additional Metadata

Data Availability (Reason not available):
Data collected in this study, and the code used to analyse the data, can be found through the Cardiff University institutional repository (ORCA; http://orca.cf.ac.uk/id/eprint/138532). Code and data are also made available via 10.5281/zenodo.4545901.

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