...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Contributions to Mineralogy and Petrology >Geochemical diversity in submarine HIMU basalts from Austral Islands, French Polynesia
【24h】

Geochemical diversity in submarine HIMU basalts from Austral Islands, French Polynesia

机译：法属波利尼西亚南方群岛海底HIMU玄武岩的地球化学多样性

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

We present the first report of geochemical data for submarine basalts collected by a manned submersible from Rurutu, Tubuai, and Raivavae in the Austral Islands in the South Pacific, where subaerial basalts exhibit HIMU isotopic signatures with highly radiogenic Pb isotopic compositions. With the exception of one sample from Tubuai, the~(40)Ar/~(39)Ar ages of the submarine basalts show no significant age gaps between the submarine and sub-aerial basalts, and the major element compositions are indistinguishable at each island. However, the variations in Pb, Sr, Nd, and Hf isotopic compositions in the submarine basalts are much larger than those previously reported in subaerial basalts. The submarine basalts with less-radiogenic Pb and radiogenic Nd and Hf isotopic compositions show systematically lower concentrations in highly Communicated by T L. Grove.incompatible elements than the typical HIMU basalts. These geochemical variations are best explained by a two-component mixing process in which the depleted asthenospheric mantle was entrained by the mantle plume from the HIMU reservoir during its upwelling, and the melts from the HIMU reservoir and depleted asthenospheric mantle were then mixed in various proportions. The present and compiled data demonstrate that the HIMU reservoir has a uniquely low ~(176)Hf/~(177)Hf decoupled from ~(143)Nd/~(144)Nd, suggesting that it was derived from an ancient subducted slab. Moreover, the Nd/Hf ratios of the HIMU basalts and curvilinear Nd-Hf isotopic mixing trend require higher Nd/Hf ratios for the melt from the HIMU reservoir than that from the depleted mantle component. Such elevated Nd/Hf ratios could reflect source enrichment by a subducted slab during reservoir formation.
机译：我们提出了南太平洋南岛鲁鲁图，图布艾和拉瓦瓦的载人潜水器收集的海底玄武岩的地球化学数据的第一份报告，那里的玄武岩表现出具有高放射性Pb同位素组成的HIMU同位素特征。除了来自图布艾的一个样本外，海底玄武岩的〜（40）Ar /〜（39）Ar年龄显示海底玄武岩和海底玄武岩之间没有明显的年龄差距，并且每个岛屿的主要元素组成都无法区分。然而，海底玄武岩中Pb，Sr，Nd和Hf同位素组成的变化比先前报道的海底玄武岩中的变化大得多。具有较低放射性的Pb和具有放射性Nd和Hf同位素组成的海底玄武岩在T.Grove。不相容元素的高度通信中显示出比典型的HIMU玄武岩系统地更低的浓度。这些地球化学变化可以通过两组分混合过程得到最好的解释，在该过程中，流失的软流圈地幔在上升期间被HIMU储层的地幔柱带走，然后将HIMU储层的熔融物和软弱的软流层地幔按不同比例混合。目前和汇编的数据表明，HIMU储层具有与〜（143）Nd /〜（144）Nd解耦的唯一低~~（176）Hf /〜（177）Hf，这表明它是来自一个古老的俯冲板块。此外，HIMU玄武岩的Nd / Hf比和曲线Nd-Hf同位素混合趋势要求来自HIMU储层的熔体的Nd / Hf比要比来自耗尽地幔组分的熔体高。如此高的Nd / Hf比值可能反映了储层形成过程中俯冲板片对源的富集。

著录项

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