Abstract:

Subaerial eruptions release vast amounts of carbon, sulfur and halogens to the atmosphere during short time-intervals, with impacts ranging in scale from the local environment to the global climate. By contrast, passive volatile degassing at the surface originating from magmatic intrusions is characterized by much lower flux, yet may outsize eruptive volatile release over long timescales. Thus, quantitative constraints on intrusive and eruptive volatile budgets are important both in order to balance global volatile cycles, and for assessing volcanic hazards.

In the first part of this talk, I will discuss intrusive volatile fluxes in Iceland based on magma degassing modelling and geochemical data from hydrothermal fluids from the Kverkfjöll and Askja volcanoes. The results suggest that the bulk of the mantle CO2 and S fluxes to the atmosphere in Iceland is supplied by intrusive, not eruptive magmatism, and is largely vented via hydrothermal areas. In the second part, I will review the pre-eruptive volatile systematics of Icelandic volcanoes using a new compilation of Icelandic melt inclusion data. Specifically, I focus on the geochemical and regional controls on magmatic sulfur contents and present petrological sulfur release estimates for >50 Icelandic eruptions.