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Mush system architecture and dynamics governing the Holocene eruptive history on the Ocean Island of El Hierro, Canary Islands

Claudia Prieto-Torrell 1,2,3, Helena Albert1,2, Meritxell Aulinas1,2, Eloi González-Esvertit3, Ilenia Arienzo4, Guillem Gisbert1,2, Valentin R. Troll5, Jose-Luis Fernandez-Turiel3, Alejandro Rodriguez-Gonzalez6, Francisco-Jose Perez-Torrado6

  • Affiliations: 1Department of Mineralogy, Petrology and Applied Geology, University of Barcelona, C/ Martí i Franquès s/n, 08028 Barcelona, Spain; 2Geomodels Research Institute, University of Barcelona, C/ Martí i Franquès s/n, 08028 Barcelona, Spain; 3Geosciences Barcelona (GEO3BCN-CSIC), C/ Lluís Solé i Sabarís s/n, 08028 Barcelona, Spain; 4Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Napoli Osservatorio Vesuviano, via Diocleziano 328, 80124 Naples, Italy; 5Department of Earth Sciences, Natural Resources & Sustainable Development (NRHU), Uppsala University, 75236 Uppsala, Sweden; 6Instituto de Estudios Ambientales y Recursos Naturales (i-UNAT), University of Las Palmas de Gran Canaria, 35017 Las Palmas de Gran Canaria, Spain

  • Presentation type: Poster

  • Presentation time: Thursday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 243

  • Programme No: 1.1.29

  • Theme 1 > Session 1

Abstract

Understanding the spatial and temporal distribution of mush-dominated systems feeding Ocean Islands (OI) is key to better constrain the magmatic processes ultimately leading to eruption. Here we present an integrated approach to unravel the dynamics of the magmatic plumbing system during the recent volcanic history at the OI of El Hierro (Canary Islands). Exhaustive sampling and detailed spatial, petrological, and geochemical characterisation were conducted on volcanic products, ranging from crystal-rich ankaramitic lavas to trachytic tephras, in 42 Holocene subaerial eruptions. Geochemical data, coupled with fractional crystallisation thermodynamic modelling and mass balance calculations, reveal that ankaramitic and porphyritic lavas with phenocryst modal abundances >10 vol% result from melt extraction and crystal accumulation. Aphyric to sub-aphyric products and porphyritic lavas with phenocryst modal abundances <10 vol% usually follow fractional crystallisation trajectories that start at ~10 wt% MgO. Minor trachytic eruptions are explained by periodic extraction of evolved melt from crystal mushes. We suggest that intricate interactions within a complex, vertically and horizontally heterogeneous, transcrustal mush-dominated system is the most likely scenario to explain the coexistence of endmember compositions, represented by ankaramites (>12 wt% MgO) and trachytes (~1 wt% MgO), which lie outside fractional crystallisation trajectories. The results allow us to put forward an updated conceptual model of the current plumbing architecture of El Hierro's volcanic system, highlighting the importance of understanding the processes that commonly govern magmatic, and especially mush-dominated plumbing systems worldwide.