Elevated gas flux and trace metal degassing from the 2014–2015 fissure eruption at the Bárðarbunga volcanic system, Iceland

• Published in: Journal of geophysical research. Solid earth Vol. 121; no. 3; pp. 1610 - 1630
• Main Authors: Gauthier, Pierre‐Jean, Sigmarsson, Olgeir, Gouhier, Mathieu, Haddadi, Baptiste, Moune, Séverine
• Format: Journal Article
• Language: English
• Published: Washington Blackwell Publishing Ltd 01-03-2016; American Geophysical Union
• Subjects: 210Pb‐210Bi‐210Po disequilibria; Carbon dioxide; Chlorine; Degassing; degassing pattern at hot spot volcanoes; Earth Sciences; Fluctuations; Geochemistry; Geophysics; high‐resolution time series satellite data; Lava; Magma; melt inclusions; Petrology; Polonium; Radon; Rifting; Sciences of the Universe; SO2 volcanic flux; Sulfur; Sulfur dioxide; Trace elements; trace metal volatility; Trace metals; Volcanic eruptions; Volcanoes; Volcanology
• ISSN: 2169-9313; 2169-9356
• DOI: 10.1002/2015JB012111

The 2014 Bárðarbunga rifting event in Iceland resulted in a 6‐month long eruption at Holuhraun. This eruption was characterized by high lava discharge rate and significant gas emission. The SO2 flux for the first 3 months was measured with satellite sensors and the petrologic method. High‐resolution time series of the satellite data give 1200 kg/s that concurs with 1050 kg/s obtained from melt inclusion minus degassed lava sulfur contents scaled to the mass of magma produced. A high‐purity gas sample, with elevated S/Cl due to limited chlorine degassing, reveals a similar degassing pattern of trace metals as observed at Kīlauea (Hawai'i) and Erta Ale (Ethiopia). This suggests a common degassing mechanism at mantle plume‐related volcanoes. The trace metal fluxes, calculated from trace element to sulfur ratios in the gas sample and scaled to the sulfur dioxide flux, are 1–2 orders of magnitude stronger at Holuhraun than Kīlauea and Erta Ale. In contrast, volcanoes at convergent margins (Etna and Stromboli, Italy) have 1–2 orders of magnitude higher trace element fluxes, most likely caused by abundant chlorine degassing. This emphasizes the importance of metal degassing as chlorine species. Short‐lived disequilibria between radon daughters, 210Pb‐210Bi‐210Po measured in the gas, suggest degassing of a continuously replenished magma batch beneath the eruption site. Earlier and deep degassing phase of carbon dioxide and polonium is inferred from low (210Po/210Pb) in the gas, consistent with magma transfer rate of 0.75 m/s.
Key Points
Satellite data and the petrologic method yield coherent SO2 flux of ~1130 kg/s
Trace element volatility is moderate as at other hot spot volcanoes
Radioactive disequilibria suggest fast magma transfer to the eruption site