A dynamic mid-crustal magma domain revealed by the 2023 to 2024 Sundhnúksgígar eruptions, Iceland
Matthews S.W., Caracciolo A., Bali E., Halldórsson S., Sigmarsson O., Guðfinnsson G., Pedersen G.B.M., Gunnarsson Robin J., Marshall E.W., Aden A.A., Ýr Gísladóttir B., Bosq C., Auclair D., Merrill H., Levillayer N., Löw N., Hlín Rúnarsdóttir R., Johnson S.M., Steinþórsson Sveinbjörn, Drouin V.
Abstract
Mid-crustal magma domains are the source of many basaltic eruptions. Lavas from individual eruptions are often chemically homogeneous, suggesting they derive from single well-mixed magma reservoirs. The 2023 to 2024 eruptions at Sundhnúksgígar in the Svartsengi volcanic system, Iceland, provide an opportunity to observe the behavior of a mid-crustal magma domain at high spatial and temporal resolution by detailed sampling and geochemical characterization. We observed substantial mantle-derived geochemical variability in the products erupted in the first hours of the December 2023, January, February, and March-May 2024 eruptions, indicating the eruptions derived from multiple magma reservoirs, which mineral-melt equilibration pressures place in the mid-crust. The unusual presence of geochemical heterogeneity in the mid-crustal magma domain provides an insight into how dynamic and complex mid-crustal magma domains can be.