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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/24779

Title: Gas compositions and helium isotopic ratios of fluid samples around Kueishantao, NE offshore Taiwan and it’s tectonic implications
Authors: Yang T.Y.;Lan T.F.;Lee H.F.;Fu C.C.;Chuang C.C.;Lo C.H.;Chen C.H.;Chen C.T.;Lee C.S.
Contributors: NTOU:Institute of Applied Geosciences
Keywords: 3He/4He ratios;Okinawa Trough;Kueishantao;hot springs;Taiwan
Date: 2005
Issue Date: 2011-10-20T08:17:39Z
Publisher: Geochemical Journal
Abstract: Kueishantao is a Holocene volcanic islet (<7,000 yrs) located at NE offshore Taiwan, and tectonically is part of west-ern extension of the Okinawa Trough. Magmatic activities are considered very active around this area on the basis of the fact that on-land fumaroles and submarine hydrothermal systems are prevailing currently. Representative bubble gas sam-ples from submarine hydrothermal vents were collected for gas composition and helium isotope analysis. The gases show similar compositions of low temperatre fumaroles in the world, i.e., with high CO2 and H2 S but low SO2 and HCl contents. They exhibit consistent high 3He/4He ratios (7.3-8.4 RA, where RA is the 3He/4He ratio of air), probably the highest 3He/4He values of gases ever reported in active hydrothermal areas of the western Pacific region. Meanwhile, seawater sam-ples around Kueishantao and other fluid samples from I-Lan Plain, the land area closest to the Kueishantao and also the southernmost part of the Okinawa Trough, show a significant excess of 3 He compositions as well. This indicates that the mantle component plays an important role for their gas sources, and implies that the mantle fluids may have invaded into I-Lan Plain. The westward opening of the Okinawa Trough may have caused thinning of the continental crust and pro-duced deep normal faults and hence, the primordial 3He is able to degas from mantle source region without significant crust contamination.
Relation: 39(5), pp.469-480
URI: http://ntour.ntou.edu.tw/handle/987654321/24779
Appears in Collections:[應用地球科學研究所] 期刊論文

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