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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Coupled ~(182)W-~(142)Nd constraint for early Earth differentiation
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Coupled ~(182)W-~(142)Nd constraint for early Earth differentiation

机译：耦合〜（182）W-〜（142）Nd约束用于早期地球分化

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摘要

Recent high precision ~(142)Nd isotope measurements showed that global silicate differentiation may have occurred as early as 30-75 Myr after the Solar System formation [Bennett V, et al. (2007) Science 318:1907-1910]. This time scale is almost contemporaneous with Earth's core formation at ～30 Myr [Yin Q, et al. (2002) Nature 418:949-952]. The ~(182)Hf-~(182)W system provides a powerful complement to the ~(142)Nd results for early silicate differentiation, because both core formation and silicate differentiation fractionate Hf from W. Here we show that eleven terrestrial samples from diverse tectonic settings, including five early Archean samples from Isua, Greenland, of which three have been previously shown with~(142)Nd anomalies, all have a homogeneous W isotopic composition, which is ~2ε-unit more radiogenic than the chondritic value. By using a 3-stage model calculation that describes the isotopic evolution in chondritic reservoir and core segregation, as well as silicate differentiation, we show that the W isotopic composition of terrestrial samples provides the most stringent time constraint for early core formation (27.5-38 Myr) followed by early terrestrial silicate differentiation (38-75 Myr) that is consistent with the terrestrial~(142)Nd anomalies.
机译：最近的高精度〜（142）Nd同位素测量表明，太阳系形成后，早在30-75 Myr时就可能发生了全球硅酸盐的分化[Bennett V等。 （2007）Science 318：1907-1910]。这个时间尺度与〜30 Myr时地球核心的形成几乎是同时发生的[Yin Q等。 （2002）Nature 418：949-952]。 〜（182）Hf-〜（182）W系统为〜（142）Nd早期硅酸盐分化提供了强有力的补充，因为岩心形成和硅酸盐分化都分离了W中的Hf。不同的构造环境，包括五个来自格陵兰岛伊苏阿的太古宙早期样本，其中三个先前已显示〜（142）Nd异常，均具有均一的W同位素组成，其放射性比软骨质值高〜2ε-单位。通过使用描述软骨质储层和岩心离析以及硅酸盐分化的同位素演化的三阶段模型计算，我们表明陆地样品的W同位素组成为早期岩心形成提供了最严格的时间限制（27.5-38 Myr）之后是早期陆地硅酸盐分化（38-75 Myr），这与陆地〜（142）Nd异常一致。

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    Frederic Moynier; rnQing-Zhu Yin; Keita Irisawa; rnMaud Boyet; rnBenjamin Jacobsen; rnMinik T. Rosing;

  • 作者单位

    Department of Geology, University of California, One Shields Avenue, Davis, CA 95616 Department of Earth and Planetary Sciences and McDonnell Center for Space Sciences, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130;

    rnDepartment of Geology, University of California, One Shields Avenue, Davis, CA 95616;

    rnDepartment of Geology, University of California, One Shields Avenue, Davis, CA 95616 Department of Earth and Planetary Sciences,Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku, Tokyo, 152-8551, Japan;

    rnLaboratoire Magmas et Volcans, Unite Mixte de Recherche Centre National de la Recherche Scieritifique 6524, Universite Blaise Pascal, 5 rue Kessler, 63038 Clermont-Ferrand Cedex, France;

    rnDepartment of Geology, University of California, One Shields Avenue, Davis, CA 95616;

    rnNordic Center for Earth Evolution, University of Copenhagen, 0ster Voldgade 5-7, 1350 Copenhagen, Denmark;

  • 收录信息 美国《科学引文索引》(SCI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
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  • 关键词

    hafnium; tungsten; hidden reservoir; Hawaii; Iceland;

    机译：铪;钨隐藏的水库;夏威夷冰岛;

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