Temporal Variations Of Gas Compositions Of Fumaroles In The Tatun Volcano Group, Northern Taiwan

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Journal Article: Temporal Variations Of Gas Compositions Of Fumaroles In The Tatun Volcano Group, Northern Taiwan

Abstract
Hydrothermal activity is common in the Tatun Volcano Group of northern Taiwan. Helium isotopic compositions of fumarolic samples show that mantle component occupies more than 60% in the previous study. Along with recent seismic results, a magma reservoir is inferred to have existed beneath the area of Da-you-keng, where fumarolic venting is the most active in Tatun Volcano Group. Progressive increases of HCl concentrations and SO2/H2S ratio in fumaroles from Da-you-keng have been observed since August 2004. The HCl concentration changed from almost the detection limit to thousands of ppm, even up to 30,000 ppm. SO2/H2S ratios varied from almost 0 to 3; hence SO2 became the dominated S species in this area. These variations were accompanied by rising temperature of fumaroles in the Tatun Volcano Group, especially in the area of Da-you-keng (from boiling point to 131°C). Meanwhile, 3He/4He ratios showed a decreasing trend but returned to normal values shortly thereafter. We propose two possible processes, 1) new magma supply and 2) recent opening of fractures in local area, to explain these observations. Based on the change of 3He/4He ratio and lack of ground deformation, we consider the latter might be more plausible.

Authors 
Hsiao-Fen Lee, Tsanyao Frank Yang, Tefang Faith Lan, Cheng-Hong Chen, Sheng-Rong Song and Shuhjong Tsao








Published Journal 
Journal of Volcanology and Geothermal Research, 2008





DOI 
Not Provided
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Citation

Hsiao-Fen Lee,Tsanyao Frank Yang,Tefang Faith Lan,Cheng-Hong Chen,Sheng-Rong Song,Shuhjong Tsao. 2008. Temporal Variations Of Gas Compositions Of Fumaroles In The Tatun Volcano Group, Northern Taiwan. Journal of Volcanology and Geothermal Research. (!) .