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

January 1, 2009

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 δ13C values (∼−6‰), 3He/4He ratios (5.9–7.2 RA), and CO2/3He ratios (1–2 × 109) in the two areas. A lower 3He/4He ratio (2.7 RA) 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.

Publication Year 2009
Title Diffuse gas emissions at the Ukinrek Maars, Alaska: Implications for magmatic degassing and volcanic monitoring
DOI 10.1016/j.apgeochem.2008.12.007
Authors William C. Evans, D. Bergfeld, R. G. McGimsey, A.G. Hunt
Publication Type Article
Publication Subtype Journal Article
Series Title Applied Geochemistry
Index ID 70035144
Record Source USGS Publications Warehouse
USGS Organization Volcano Hazards Program