| Kr and Xe isotopic compositions of Fe-Mn crusts from the western and central Pacific Ocean and implications for their genesis |
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| 作者姓名： | BU Wenrui SHI Xuef LI Li ZHANG Mingjie G. P. Glasby LIU Jihua |
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| 作者单位： | Key Laboratory of Marine Sedimentology & Environmental Geology, First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China;Key Laboratory of Marine Sedimentology & Environmental Geology, First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China;Key Laboratory of Marine Sedimentology & Environmental Geology, First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China;School of Resources and Environment, Lanzhou University, Lanzhou 730000, China;Department of Geochemistry, Geowissenschafliches Zentrum der Universitat Göttingen (GZG), Göttingen 37077, Germany;Key Laboratory of Marine Sedimentology & Environmental Geology, First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China |
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| 基金项目： | The National Natural Science Foundation of China under contract No. 40706028. |
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| 摘 要： | Kr and Xe nuclide abundance and isotopic ratios of the uppermost layer of Fe-Mn Crusts from the western and central Pacific Ocean have been determined. The results indicate that the Kr and Xe isotopic composi-tions, like that of He, Ne and Ar, can be classified into two types： low3He/4He type and high3He/4He type. The low3He/4He type crusts have low84Kr and132Xe abundance, while the high3He/4He type crusts have high84Kr and132Xe abundance. The82Kr/84Kr ratios of the low3He/4He type crusts are lower than that of the air, while the83Kr/84Kr and86Kr/84Kr ratios are higher than those of the air. The Kr isotopic ratios of the high-er3He/4He type crusts are quite similar to those of the air. The128Xe/132Xe,130Xe/132Xe and131Xe/132Xe ratios of the low3He/4He type sample are distinctly lower than those of the air, whereas the129Xe/132Xe,134Xe/132Xe and136Xe/132Xe ratios are higher than those of the air. The low3He/4He type samples have the diagnostic characteristics of the MORB, with excess129, 131, 132, 134, 136Xe relative to130Xe compared with the solar wind. The128Xe/132Xe,130Xe/132Xe and131Xe/132Xe ratios of the high3He/4He type samples are slightly higher than those of the air, and the129Xe/132Xe,134Xe/132Xe and136Xe/132Xe ratios are qiute similar to those of the air. The noble gases in the Fe-Mn crusts are derived from the lower mantle, and they are a mixture of lower mantle primitive component, radiogenic component and subduction recycled component. The helium isotopic ra-tios of the low mantle reservoir are predominantly controlled by primitive He （3He） and U and Th radiogenic decayed He （4He）, but the isotopic ratios of the heavier noble gases, such as Ar, Kr and Xe, are controlled to different extent by recycling of subduction components. The difference of the noble isotopic compositions of the two type crusts is the result of the difference of the noble isotopic composition of the mantle source reservoir underneath the seamounts the crusts occurred, the noble gases of the high3He/4He type crusts are
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| 关 键 词： | 同位素组成 氪同位素 铁锰结壳 太平洋 西部 氙 起源 稀有气体 |
| 收稿时间： | 2012/6/18 0:00:00 |
| 修稿时间： | 8/7/2013 12:00:00 AM |
Kr and Xe isotopic compositions of Fe-Mn crusts from the western and central Pacific Ocean and implications for their genesis |
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| BU Wenrui,SHI Xuef,LI Li,ZHANG Mingjie,G. P. Glasby,LIU Jihua.Kr and Xe isotopic compositions of Fe-Mn crusts from the western and central Pacific Ocean and implications for their genesis[J].Acta Oceanologica Sinica,2014,33(8):26-33. |
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| Authors: | BU Wenrui SHI Xuef LI Li ZHANG Mingjie G P Glasby and LIU Jihua |
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| Institution: | 1.Key Laboratory of Marine Sedimentology & Environmental Geology, First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China2.School of Resources and Environment, Lanzhou University, Lanzhou 730000, China3.Department of Geochemistry, Geowissenschafliches Zentrum der Universitat Göttingen (GZG), Göttingen 37077, Germany |
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| Abstract: | Kr and Xe nuclide abundance and isotopic ratios of the uppermost layer of Fe-Mn Crusts from the western and central Pacific Ocean have been determined. The results indicate that the Kr and Xe isotopic compositions, like that of He, Ne and Ar, can be classified into two types: low 3He/4He type and high 3He/4He type. The low 3He/4He type crusts have low 84Kr and 132Xe abundance, while the high 3He/4He type crusts have high 84Kr and 132Xe abundance. The 82Kr/84Kr ratios of the low 3He/4He type crusts are lower than that of the air, while the 83Kr/84Kr and 86Kr/84Kr ratios are higher than those of the air. The Kr isotopic ratios of the higher 3He/4He type crusts are quite similar to those of the air. The 128Xe/132Xe, 130Xe/132Xe and 131Xe/132Xe ratios of the low 3He/4He type sample are distinctly lower than those of the air, whereas the 129Xe/132Xe, 134Xe/132Xe and 136Xe/132Xe ratios are higher than those of the air. The low 3He/4He type samples have the diagnostic characteristics of the MORB, with excess 129,131,132,134,136Xe relative to 130Xe compared with the solar wind. The 128Xe/132Xe, 130Xe/132Xe and 131Xe/132Xe ratios of the high 3He/4He type samples are slightly higher than those of the air, and the 129Xe/132Xe, 134Xe/132Xe and 136Xe/132Xe ratios are qiute similar to those of the air. The noble gases in the Fe-Mn crusts are derived from the lower mantle, and they are a mixture of lower mantle primitive component, radiogenic component and subduction recycled component. The helium isotopic ratios of the low mantle reservoir are predominantly controlled by primitive He (3He) and U and Th radiogenic decayed He (4He), but the isotopic ratios of the heavier noble gases, such as Ar, Kr and Xe, are controlled to different extent by recycling of subduction components. The difference of the noble isotopic compositions of the two type crusts is the result of the difference of the noble isotopic composition of the mantle source reservoir underneath the seamounts the crusts occurred, the noble gases of the high 3He/4He type crusts are derived mainly from EM-type lower mantle reservoir, and the noble gases in the low 3He/4He type crusts are derived mainly from HIMU-type lower mantle reservoir. |
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| Keywords: | Fe-Mn crusts Kr and Xe isotopes mantle reservoir Pacific Ocean subduction recycling |
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