Deciphering the Holocene magmatic plumbing system dynamics beneath El Hierro (Canary Islands)

Ocean Island Basalts (OIBs) provide a unique window into the deep Earth dynamics that govern the formation of volcanic islands. A comprehensive understanding of OIB systems often requires multidisciplinary approaches, providing insights into which processes operate from source to surface along complex pathways of magma transport and storage. Investigating these processes during the Holocene allows for the characterisation of magmatic architectures and eruptive dynamics over a period suf¿¿ciently prolonged and yet close to the present day, making it representative of the current and future behaviour of volcanic areas. The Canary Archipelago (NW African coast) represents an exceptional natural laboratory for these purposes. Here, we provide an integrated approach to the dynamics of the magmatic plumbing system beneath El Hierro, which is the westernmost and youngest island of the Canaries. Through the investigation of 59 Holocene subaerial eruptions, we provide a detailed petrological and geochemical characterisation of volcanic products ranging from felsic pyroclasts to ankaramitic lavas with crystal contents up to 51%. Results are integrated within fractional crystallisation modelling and mass balance calculations, revealing different degrees of crystal accumulation and melt extraction on magmas with MgO contents above 10 wt%. These results are combined with recently updated geological mapping, as well as with new geochronological data supported by stratigraphic and geomorphological constraints. This holistic approach allows us to illustrate the spatial and temporal distributions of the subaerial volcanism at El Hierro, as well as their implications for magmatic evolution and plumbing architecture. Our ¿¿ndings shed light on the complex magmatic processes that have governed the evolution of El Hierro¿s volcanic system during the Holocene, with broader implications for the study of OIB magmatism in similar settings worldwide.