Geochemical investigation of the hydrothermal system on Akutan Island, Alaska, July 2012

D. Bergfeld; Jennifer L. Lewicki; William C. Evans; Andrew G. Hunt; Kinga Revesz; Mark Huebner

doi:10.3133/sir20135231

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Geochemical investigation of the hydrothermal system on Akutan Island, Alaska, July 2012

D. Bergfeld·Jennifer L. Lewicki·William C. Evans·Andrew G. Hunt·Kinga Revesz·Mark Huebner

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Abstract

We have studied the geochemistry of the hot springs on Akutan Island in detail for the first time since the early 1980s. Springs in four discrete groups (A-D) along Hot Springs Creek showed generally higher temperatures and substantially higher Na, Ca, and Cl concentrations than previously reported, and total hot-spring discharge has also increased markedly. The springs now account for a heat output of ~29 MW, about an order of magnitude more than in 1981. Gas samples from the hot springs and from a fumarolic area on the flank of Akutan Volcano show high 3 He/ 4 He ratios (>6.4 RA) after correction for air contamination and reveal a common magmatic heat source. Hot-spring gases are unusually rich in N 2 , Ar, and CH 4 , suggesting that the water has boiled and lost CO 2 during upflow beneath the flank fumarole field. Gas geothermometry calculations applied to the flank fumarole field implies temperatures of 200–240 °C for the reservoir, and Na-K-Ca geothermometry implies temperatures near 180 °C for the outflow waters that feed the hot springs. The results of our study confirm the existence of a substantial geothermal resource on the island.

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Source-reported bounding extent: 54.099921° to 54.168981° latitude; -166.0067° to -165.760835° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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D. Bergfeld, Jennifer L. Lewicki, William C. Evans, Andrew G. Hunt, Kinga Revesz, Mark Huebner. 2014. Geochemical investigation of the hydrothermal system on Akutan Island, Alaska, July 2012. https://doi.org/10.3133/sir20135231

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