Reaction path models of magmatic gas scrubbing

Gas–water–rock reactions taking place within volcano-hosted hydrothermal systems scrub reactive, water-soluble species (sulfur, halogens) from the magmatic gas phase, and as such play a major control on the composition of surface gas manifestations. A number of quantitative models of magmatic gas sc...

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Bibliographic Details
Published in:Chemical geology 2016-01, Vol.420, p.251-269
Main Authors: Di Napoli, Rossella, Aiuppa, Alessandro, Bergsson, Baldur, Ilyinskaya, Evgenia, Pfeffer, Melissa Anne, Guðjónsdóttir, Sylvía Rakel, Valenza, Mariano
Format: Article
Language:English
Subjects:
Computer simulation
EQ3/6
Fluid flow
Fluids
Gas phases
Gas scrubbing
Gas-water-rock interaction
Hydrothermal systems
Iceland
Magmatic gas scrubbing
Mathematical models
Reservoirs
Volcanic activity
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Summary:Gas–water–rock reactions taking place within volcano-hosted hydrothermal systems scrub reactive, water-soluble species (sulfur, halogens) from the magmatic gas phase, and as such play a major control on the composition of surface gas manifestations. A number of quantitative models of magmatic gas scrubbing have been proposed in the past, but no systematic comparison of model results with observations from natural systems has been carried out, to date. Here, we present the results of novel numerical simulations, in which we initialized models of hydrothermal gas–water–rock at conditions relevant to Icelandic volcanism. We focus on Iceland as an example of a “wet” volcanic region where scrubbing is widespread. Our simulations were performed (using the EQ3/6 software package) at shallow (temperature100°C. We find that this range of model gas compositions reproduces well the (H2O-CO2-STOT) compositional range of reservoir waters and surface gas emissions in Iceland. From this validation of the model in an extreme end-member environment of high scrubbing, we conclude that EQ3/6-based reaction path simulations offer a realistic representation of gas–water–rock interaction processes occurring underneath active magmatic-hydrothermal systems. •EQ3/6 is used to simulate magmatic gas scrubbing•Model fluid compositions match well natural hydrothermal fluid compositions.•Magmatic gas scrubbing is a recurrent process in Icelandic hydrothermal systems.
ISSN:0009-2541
1872-6836
DOI:10.1016/j.chemgeo.2015.11.024