The Petrology and Geochemistry of the 2021 Fagradalsfjall Eruption, Iceland
Résumé
The 2021 Fagradalsfjall eruption is the first on Iceland's Reykjanes Peninsula in ∼800 years and likely is the harbinger of a renewed period of volcanism on the peninsula, as evidenced by subsequent eruptions at Fagradalsfjall and Svartsengi. For evaluating the potential hazard of the new eruptive period, we must understand how these new volcanic systems work. Here, we investigate the chemical and mineralogical properties of the 2021 Fagradalsfjall lava in order to identify the structure, igneous processes, and origins of the magmas feeding the new eruptions. We find that the 2021 eruption lavas have highly unusual compositions compared to most Icelandic basaltic eruptions and are sourced deeper, from magma bodies at the bottom of the crust. In contrast to the rather homogeneous chemical compositions of most basaltic eruptions, the compositions of the 2021 Fagradalsfjall lavas are extremely variable. This is explained by the lava being fed from multiple independent magma bodies close to the crust-mantle boundary. The 2021 Fagradalsfjall eruption is the first that allows direct investigation of a "living" magma system hosted near the crust-mantle boundary. The Fagradalsfjall deep magma system is characterized by many, compositionally diverse, magma bodies that exchange magma with one another on days-to-weeks timescales and occasionally intrude into the overlying crust.
Domaines
Planète et Univers [physics]| Origine | Fichiers éditeurs autorisés sur une archive ouverte |
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