| 地幔中水的存在形式和含水量 |
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| 引用本文： | 谢鸿森,侯渭,周文戈.地幔中水的存在形式和含水量[J].地学前缘,2005,12(1):55-60. |
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| 作者姓名： | 谢鸿森 侯渭 周文戈 |
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| 作者单位： | 中国科学院,地球化学研究所,贵州,贵阳,550002;中国科学院,地球化学研究所,贵州,贵阳,550002;中国科学院,地球化学研究所,贵州,贵阳,550002 |
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| 基金项目： | 教育部科学技术研究项目;中国科学院知识创新工程项目 |
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| 摘 要： | 水以含水变质矿物、无水硅酸盐矿物(橄榄石、辉石等)及其高压结构相(β橄榄石、γ橄榄石、钙钛矿相、方镁铁矿等)、高密度含水镁硅酸盐和熔体的形式存在于地幔各层圈中。根据各类玄武岩水含量推断出的上地幔源区的水含量,和由地幔岩主要矿物———橄榄石的水含量估算出的上地幔水含量(质量分数)很接近,在0.02%左右。以橄榄石和辉石高压相的水含量为依据,进行了过渡带和下地幔水含量的估算,其结果是:过渡带和下地幔上部的水含量(质量分数)为1.48%,下地幔下部水含量(质量分数)为0.21%。据此,计算出的地幔各层圈的总水量表明,地幔水的74%以上存在于过渡带和下地幔上部。将地幔总水量和现代海洋总水量之和作为地球总水量,计算出现代海洋总水量约占全球总水量(质量分数)的6.6%,这个结果与笔者根据地球的球粒陨石成分模型计算出的总水量(6%)十分接近。
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| 关 键 词： | 地幔 水 地幔含水相 |
| 文章编号： | 1005-2321(2005)01-0055-06 |
| 修稿时间： | 2004年11月15 |
Water content in the Earth's mantle |
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| XIE Hong-sen,HOU Wei,ZHOU Wen-ge.Water content in the Earth's mantle[J].Earth Science Frontiers,2005,12(1):55-60. |
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| Authors: | XIE Hong-sen HOU Wei ZHOU Wen-ge |
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| Abstract: | Water in the Earths mantle exists in hydrated metamorphic minerals, in anhydrous silicate minerals (olivine, pyroxene etc.) and their high-pressure structure phases \β-olivine(wadsleyite), γ-olivine(ringwoodite), majorite, ilmenite phase(akimotoite), perovskite phase, magnesio-wuestite, etc.\], in dense hydrous magnesium silicate (DHMS). The water content of the upper mantle as inferred from the water content of basalt is 0.02%. This is consistent with the value estimated from olivine in mantle's xenoliths. According to the water contents in high-pressure phases of olivine and pyroxene, the water contents of transition zone and lower mantle are estimated. The water content of the transition zone and the upper part of lower mantle( (410～1 000 km) is) 1.48%, and the water content of other part of lower mantle (1 000～2 900 km) is 0.21%. From this, the quantity of water in each layer of mantle can be estimated. Results show that more than 74% of water in mantle, exists in the transition zone and the upper part of the lower mantle. If the quantity of water in the Earth is equal to the summation of water in the mantle and water in the sea, then the amount of water in sea is 6.6% of the total water in the Earth. This result is consistent with that inferred from the chondrite's compositions. |
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| Keywords: | mantle water hydrous phases of mantle |
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