Fig. 5: Oxygen isotope results.
a Timeline of δ18O values obtained for glasses from the 2021 Fagradalsfjall eruption over the period 20th March to 26th August 2021. Analytical uncertainty is displayed as an inset. A total of 47 analyses are presented (repeat analyses were made on four samples; in these cases the mean value is plotted), which yielded an overall mean of 5.4 (±0.3‰ 2 SD). The mean δ18O value for each month is also shown in italics. The range of values from the previous Icelandic eruption at Holuhraun (Central Iceland) in 2014–1521 is provided for comparison. Note that the Fagradalsfjall data overlap Atlantic MORB22 and Reykjanes Ridge glasses19. b Frequency distribution plot (frequency = number of samples) comparing the new 2021 Fagradalsfjall eruption data to glasses from the 2014–15 Holuhraun eruption21, Grímsvötn-Gjálp17, the 1783–4 Laki eruption17, and the Reykjanes Ridge19. Equilibrium melt δ18O values were calculated from Reykjanes Peninsula olivine data in refs. 25,28 using fractionation factors calculated after ref. 61. Bin size is 0.1‰, equivalent to 1σ uncertainty on the data. c Δ′17O values obtained for three Fagradalsfjall samples compared to values obtained for the San Carlos olivine (SCO) standard at the University of Oregon (UO) and the mantle range37. Abbreviations: Apr April, Atl Atlantic, Aug August, Mar March, MORB Mid-Ocean Ridge Basalt, Reykjanes VB Reykjanes Volcanic Belt.
