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Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/3723

Authors: Burton, M. R.*
Mader, H. M.*
Polacci, M.*
Title: The role of gas percolation in quiescent degassing of persistetly active basaltic volcanoes
Title of journal: Earth and Planetary Research Letters
Series/Report no.: /264 (2007)
Publisher: Elsevier
Issue Date: 8-Sep-2007
DOI: 10.1016/j.epsl.2007.08.028
URL: http://www.sciencedirect.com/science/journal/0012821X
Keywords: Stromboli
gas
Abstract: Using constraints from literature data on the petrology and texture of erupted material from Stromboli and geochemical measurements of gas emissions together with a model of gas solubility we construct a conceptual model of quiescent degassing for this volcano. We find that within a pressure range between 100 MPa and 50 MPa (∼3.6 km and ∼1.8 km depth respectively) vesiculating magma ascending within the conduit becomes permeable to gas flow and a transition from closed- to open-system degassing takes place. Above the transition, gas, rich in the most insoluble gases, flows up through degassing magma, and thereby becomes enriched in more soluble gases during ascent to the surface. The final gas emission is therefore a superposition of gases released from magma above the percolation transition and gas that has evolved in closed-system below the transition. Steady-state gas release from Stromboli can only be sustained via magma circulation, driven by the density variation between ascending vesiculating magma and descending degassed magma. By balancing the buoyant force of ascending vesiculating magma against the viscous resistance produced by travelling through descending, degassed magma in a simple flow model we determine that a cylindrical conduit diameter of 2.5–2.9 m produces the magma mass flow rate of 575 kg s−1, required to account for the observed quiescent SO2 gas flux on Stromboli of ∼2.3 kg s−1 (200 td−1).
Appears in Collections:04.08.01. Gases
Papers Published / Papers in press

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