The 2023 Litli-Hrútur eruption of the Fagradalsfjall Fires, SW-Iceland : Insights from trace element compositions of olivine

• This study provides data on the trace element composition of olivine from olivine tholeiitic basalts sampled during the July-August 2023 Litli-Hrutur eruption of the Fagradalsfjall Fires in the Reykjanes Volcanic Belt. Chemistry of the Litli-Hrutur olivine is characteristic for volcanic olivine crystals that represent products of magmatic crystallisation. The investigated olivine megacrysts show forsterite (Fo) content in the range of 81 (rims) to 85 (cores) mole percent [defined as Fo = Mg/(Mg + Fe)]. Olivine Ni concentrations (1540-1840 ppm) correlate positively with the Fo contents. In addition, Ca contents show a range from 1890 to 2460 ppm at relatively low Ti concentrations. Olivine from the Litli-Hrutur samples shows an equilibrium with peridotitic mantle melts, yet the data show that the 2023 Litli-Hrutur and the 2022 Meradalir olivine populations crystallised from compositionally more evolved magma batches than olivine crystals from the 2021 Geldingadalir eruption of the Fagradalsfjall Fires. These results imply that magmatic differentiation has taken place between the initial 2021 events and the subsequent 2022 and 2023 eruptions as a result of crystal-liquid fractionation, shifting the overall magma chemistry towards more evolved compositions with time. This implies that fractional crystallisation in sub -alkaline magma reservoirs operates on the scale of years, which is a fundamental advance in our understanding of these common magmatic systems.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Geokemi (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Geochemistry (hsv//eng)

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Geofysik (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Geophysics (hsv//eng)

Nyckelord

olivine

Reykjanes Peninsula

Litli - Hrútur lava

peridotitic mantle

LA - ICP - MS

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)