Diffuse gas emissions at the Ukinrek Maars, Alaska: Implications for magmatic degassing and volcanic monitoring

Evans, W. C.; Bergfeld, D.; McGimsey, R. G.; Hunt, A. G.

Abstract:

Diffuse CO₂ efflux near the Ukinrek Maars, two small volcanic craters that formed in 1977 in a remote part of the Alaska Peninsula, was investigated using accumulation chamber measurements. High CO₂ efflux, in many places exceeding 1000 g m^-2 d^-1, was found in conspicuous zones of plant damage or kill that cover 30,000-50,000 m² in area. Total diffuse CO₂ emission was estimated at 21-44 t d^-1. Gas vents 3-km away at The Gas Rocks produce 0.5 t d^-1 of CO₂ that probably derives from the Ukinrek Maars basalt based on similar ??¹³C values (???-6???), ³He/⁴He ratios (5.9-7.2 R_A), and CO₂/³He ratios (1-2 ?? 10⁹) in the two areas. A lower ³He/⁴He ratio (2.7 R_A) and much higher CO₂/³He ratio (9 ?? 10¹⁰) in gas from the nearest arc-front volcanic center (Mount Peulik/Ugashik) provide a useful comparison. The large diffuse CO₂ emission at Ukinrek has important implications for magmatic degassing, subsurface gas transport, and local toxicity hazards. Gas-water-rock interactions play a major role in the location, magnitude and chemistry of the emissions.

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Article

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70035144

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Evans, W. C.; Bergfeld, D.; McGimsey, R. G.; Hunt, A. G.

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535

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English

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Applied Geochemistry

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Diffuse gas emissions at the Ukinrek Maars, Alaska: Implications for magmatic degassing and volcanic monitoring; 2009; Article; Journal; Applied Geochemistry; Evans, W. C.; Bergfeld, D.; McGimsey, R. G.; Hunt, A. G.