• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Nature >~(142)Nd evidence for an enriched Hadean reservoir in cratonic roots
【24h】

~(142)Nd evidence for an enriched Hadean reservoir in cratonic roots

机译：〜（142）Nd证据表明克拉通根系富含哈德滩储层

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The isotope ~(146)Sm undergoes a-decay to ~(142)Nd, with a half-life of 103 million years. Measurable variations in the ~(142)Nd/~(144)Nd values of rocks resulting from Sm-Nd fractionation could therefore only have been produced within about 400 million years of the Solar System's formation (that is, when ~(146)Sm was extant). The ~(142)Nd/~(144)Nd compositions of terrestrial rocks are accordingly a sensitive monitor of the main silicate differentiation events that took place in the early Earth. High ~(142)Nd/~(144)Nd values measured in some Archaean rocks from Greenland hint at the existence of an early incompatible-element-depleted mantle. Here we present measurements of low ~(142)Nd/~(144)Nd values in 1.48-gigayear-(Gyr)-old lithospheric mantle-derived alkaline rocks from the Khariar nepheline syenite complex in southeastern India. These data suggest that a reservoir that was relatively enriched in incompatible elements formed at least 4.2 Gyr ago and traces of its iso-topic signature persisted within the lithospheric root of the Bastar craton until at least 1.48 Gyr ago. These low ~(142)Nd/~(144)Nd compositions may represent a diluted signature of a Hadean (4 to 4.57 Gyr ago) enriched reservoir that is characterized by even lower values. That no evidence of the early depleted mantle has been observed in rocks younger than 3.6 Gyr (refs 3,4,7) implies that such domains had effectively mixed back into the converting mantle by then. In contrast, some early enriched components apparently escaped this fate. Thus, the mantle sampled by magmatism since 3.6 Gyr ago may be biased towards a depleted composition that would be balanced by relatively more enriched reservoirs that are 'hidden' in Hadean crust, the D" layer of the lowermost mantle or, as we propose here, also within the roots of old cratons.
机译：同位素〜（146）Sm经历〜（142）Nd的衰变，半衰期为1.03亿年。因此，由Sm-Nd分馏产生的岩石的〜（142）Nd /〜（144）Nd值的可测量变化只能在太阳系形成后约4亿年内产生（即，当〜（146）Sm是现存的）。因此，地球岩石的〜（142）Nd /〜（144）Nd组成是敏感的监测器，用于监测地球早期发生的主要硅酸盐分化事件。在格陵兰一些古生岩石中测得的高〜（142）Nd /〜（144）Nd值暗示着早已存在不相容元素耗尽的地幔。在这里，我们介绍了印度东南部Khariar霞石正长岩复杂的1.48千兆年（Gyr）年代的岩石圈地幔衍生碱性岩中低〜（142）Nd /〜（144）Nd值的测量结果。这些数据表明，至少在4.2 Gyr之前形成了相对富含不相容元素的储层，其同位素特征的痕迹一直存在于Bastar克拉通的岩石圈根中，直到至少1.48 Gyr为止。这些低〜（142）Nd /〜（144）Nd组成可能代表了哈德族（4至4.57 Gyr以前）富集储层的稀释特征，其特征在于甚至更低的值。在小于3.6 Gyr的岩石中没有观察到早期耗尽地幔的证据（参考文献3、4、7），暗示着这些区域到那时已有效地混入转换地幔中。相反，一些早期丰富的成分显然摆脱了这种命运。因此，自3.6年前以来由岩浆作用取样的地幔可能偏向贫化的成分，该成分将被相对更富集的储层所平衡，这些储层被“隐藏”在Hadean地壳，最低地幔的D”层或我们这里提出的，也属于旧克拉通的根基。

著录项

  • 来源
    《Nature》 |2009年第25期|1118-1121|共4页
  • 作者

    Dewashish Upadhyay; Erik E. Scherer; Klaus Mezger;

  • 作者单位

    Zentrallabor fur Geochronologie, Institut fur Mineralogie, Universitat Munster, Corrensstrasse 24, 48149 Miinster, Germany.;

    Zentrallabor fur Geochronologie, Institut fur Mineralogie, Universitat Munster, Corrensstrasse 24, 48149 Miinster, Germany.;

    Zentrallabor fur Geochronologie, Institut fur Mineralogie, Universitat Munster, Corrensstrasse 24, 48149 Miinster, Germany.;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);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
  • 中图分类
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号