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Can halogen contents of olivine-hosted melt inclusions track time-dependent sampling of mantle heterogeneities during single eruptions?

Roxane Buso1 , Bridie V. Davies1, María Asensio-Ramos2, Enikö Bali3, Ray Burgess1, Mike Burton1, Katy Chamberlain4, Sæmundur Halldórsson3, David A. Neave1, Matt Pankhurst5, Margherita Polacci1 and Margaret E. Hartley1

  • Affiliations: 1Department of Earth and Environmental Sciences, The University of Manchester, Manchester, UK; 2Instituto Volcanológico de Canarias (INVOLCAN), Puerto de la Cruz, Spain; 3Nordic Volcanological Centre, Institute of Earth Sciences, University of Iceland, Reykjavík, Iceland; 4Department of Earth, Ocean & Ecological Sciences, University of Liverpool, Liverpool, UK; 5Gaiaxiom Pty Ltd, Denmark 

  • Presentation type: Talk

  • Presentation time: Thursday 09:15 - 09:30, Room S150

  • Programme No: 1.1.4

  • Theme 1 > Session 1

Abstract

Volatile heterogeneity in the Earth's mantle has been created by volatile input and output over time. Basaltic eruptions at oceanic islands can sample these mantle heterogeneities and capture their diverse geochemical signatures in crystal-hosted melt inclusions. However, the extent to which melting and mobilisation of mantle heterogeneities influence magma volatile budgets during a single eruption remains poorly understood, because the time-dependencies of those processes are not well constrained by measurements. To address this, we plan to measure Cl, Br and I in melt inclusions from Iceland and the Canary Islands. Halogens are sensitive tracers of recycled material, making them ideal for tracking time-dependent sampling of different mantle reservoirs. We will use neutron-irradiated noble gas mass spectrometry to measure halogens, following two different approaches: bulk analyses of single olivine grains containing melt inclusions, and in situ analyses of individual melt inclusions. Our first objective is to constrain the halogen signatures of three mantle types by analyzing melt inclusions from three compositionally distinct localities: Borgarhraun (depleted) and Stapafell (enriched) (Iceland), and El Hierro (recycled) (Canary Islands). Secondly, we will use the obtained halogen signatures to construct high-resolution time series of halogen content in melts and their mantle sources for two recent eruptions showing time-dependent geochemical variability: 2021--2022 Fagradalsfjall and 2021 Cumbre Vieja (La Palma, Canary Islands). Finally, by linking temporal variations in magma halogen content with in situ gas flux measurements and observed changes in eruptive style, we aim to evaluate whether time-dependent differential sampling of heterogeneous mantle reservoirs influences eruption dynamics.