Fig. 6: Hydrogen isotope results.
a δD-H2O variation in glasses from the 2021 Fagradalsfjall eruption compared to the MORB UOB (University of Oregon Basalt) glass standard30. The δD range for fresh MORB is drawn after ref. 29. The mild decrease in δD observed in some of the Fagradalsfjall samples is likely due to near-surface degassing (Batch and Rayleigh degassing curves shown from a starting composition similar to UOB). Reference data for Reykjanes Ridge basalts are plotted after ref. 62. Analytical uncertainty decreases with increasing water content; error bars are displayed for low water samples and are otherwise smaller than symbol size. b Frequency distribution plot of H2O contents in Fagradalsfjall glasses, including samples with low water contents (0.00–0.03 wt.% H2O) that have no accompanying δD values. There is no evidence for magma interaction with seawater or meteoric water that would hydrate the glass and cause an increase and decrease in H2O contents and δD values, respectively. Additional H2O data for Reykjanes Ridge and Reykjanes Peninsula basalts are plotted after ref. 41. Abbreviations as before.
