Noble gas elemental and isotopic abundances in deep-sea trenches in the western Pacific
Noble gas elemental and isotopic abundances in deep-sea trenches in the western Pacific
复制标题
西太平洋深海海沟稀有气体元素和同位素丰度
DOI：
10.1016/0012-821x(87)90190-7
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发表时间：
1987
影响因子：
5.3
通讯作者：
J. Boulègue
中科院分区：
文献类型：
--
作者：
G. Igarashi;Masako Kodera;M. Ozima;Y. Sano;H. Wakita;J. Boulègue
测定了南开海槽、日本海沟和千岛海沟5个不同采样点的7个深海水样的稀有气体元素丰度和同位素丰度。样品是由“鹦鹉螺”号载人潜水器获取的。大多数采样点都与文蛤菌落和/或液体喷口有关。在天龙峡谷入海口3830米深的文蛤群附近几公里处采集的海水样本中，观察到了超标的3He/4He和He浓度。相对于1°C空气饱和海水中的稀有气体(Ne、Ar、Kr和Xe)的浓度，该样品中的稀有气体(Ne、Ar、Kr和Xe)的浓度呈现从Ne到Xe的递减，这可归因于热水(≳15°C)和冷水(⋍1°C)的混合。样品中Ne、Ar、Kr和Xe的同位素组成为大气。这些观察结果可能反映了天龙峡谷周围热孔隙水的喷发。所有其他样品显示，相对于1℃空气饱和海水，所有惰性气体的浓度都显着超标，同位素组成为大气。这种惰性气体浓度的超标可能是样品中的空气污染。然而，对Kaiko样本的碳氢化合物分析结果表明，如此大规模的空气污染是不可能的。深海沉积物中天然气水合物的分解是观测到的惰性气体浓度过高的更可能的解释。
Noble gas elemental and isotopic abundances were measured in seven deep-sea water samples from five different sampling sites in the Nankai Trough, the Japan Trench and the Kuril Trench. The samples were obtained by the manned submersible “Nautile”. Most of the sampling sites are associated with clam colonies and/or fluid venting. Excesses both in3He/4He ratio and He concentration are observed in a seawater sample collected a few kilometers off the clam colonies which were found at a depth of 3830 m at the mouth of the Tenryu Canyon. Concentrations of noble gases (Ne, Ar, Kr and Xe) in this sample show progressive depletion from Ne to Xe relative to those in 1°C air-saturated seawater, which can be attributed to mixing of hot water (≳ 15°C) with cold ambient water (⋍ 1°C). Isotopic compositions of Ne, Ar, Kr and Xe in this sample are atmospheric. These observations may reflect venting of hot pore water around the Tenryu Canyon. All the other samples show a significant excess in concentration of all noble gases relative to 1°C air-saturated seawater and the isotopic compositions are atmospheric. This excess of noble gas concentrations may appear to be air contamination in the samples. However, results of hydrocarbon analyses of the Kaiko samples imply that such large amount of air contamination is improbable. Decomposition of gas hydrate in deep-sea sediments is a more likely explanation for the observed excess of noble gas concentration.