Trace-element characteristics of east–west mantle geochemical hemispheres

IF 2 4区地球科学 Q3 GEOSCIENCES, MULTIDISCIPLINARY Comptes Rendus Geoscience Pub Date : 2019-02-01 DOI:10.1016/j.crte.2018.09.007

Hikaru Iwamori , Hitomi Nakamura , Masaki Yoshida , Takashi Nakagawa , Kenta Ueki , Atsushi Nakao , Tatsuji Nishizawa , Satoru Haraguchi

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引用次数: 1

Abstract

Recent statistical analyses on the isotopic compositions of oceanic, arc, and continental basalts have revealed that the Earth's mantle is broadly divided into eastern and western hemispheres. The present study aimed to characterize the isotopically defined east–west geochemical hemispheres using trace-element concentrations. Basalt data with Rb, Sr, Nd, Sm, Pb, Th, and U in addition to the isotopic ratios ⁸⁷Sr/⁸⁶Sr, ¹⁴³Nd/¹⁴⁴Nd, ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb, and ²⁰⁸Pb/²⁰⁴Pb were selected mostly from the GEOROC and PetDB databases. A total of 4787 samples were used to investigate the global geochemical variations. The results show that the wide trace-element variations are broadly explained by the melting of melt-metasomatized and fluid-metasomatized mantle sources. The larger amount of the fluid component derived from subducted plates in the eastern hemisphere than that in the western hemisphere is inferred from the basalts. These characteristics support the hypothesis that focused subduction towards the supercontinent created the mantle geochemical hemispheres.

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东西地幔地球化学半球微量元素特征

最近对海洋玄武岩、弧玄武岩和大陆玄武岩同位素组成的统计分析表明，地幔大致分为东西半球。本研究旨在利用微量元素浓度来表征同位素确定的东西地球化学半球。玄武岩中Rb、Sr、Nd、Sm、Pb、Th、U以及同位素比值87Sr/86Sr、143Nd/144Nd、206Pb/204Pb、207Pb/204Pb和208Pb/204Pb等玄武岩数据主要来自于GEOROC和PetDB数据库。利用4787份样品对全球地球化学变化进行了研究。结果表明，大范围的微量元素变化可以用熔融交代和流体交代地幔源的熔融作用来解释。来自东半球俯冲板块的流体成分比来自西半球的流体成分多，这是由玄武岩推断出来的。这些特征支持了向超大陆集中俯冲形成地幔地球化学半球的假设。

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来源期刊

Comptes Rendus Geoscience 地学-地球科学综合

CiteScore

2.80

自引率

14.30%

发文量

审稿时长

5.9 weeks

期刊介绍： Created in 1835 by physicist François Arago, then Permanent Secretary, the journal Comptes Rendus de l''Académie des sciences allows researchers to quickly make their work known to the international scientific community. It is divided into seven titles covering the range of scientific research fields: Mathematics, Mechanics, Chemistry, Biology, Geoscience, Physics and Palevol. Each series is led by an editor-in-chief assisted by an editorial committee. Submitted articles are reviewed by two scientists with recognized competence in the field concerned. They can be notes, announcing significant new results, as well as review articles, allowing for a fine-tuning, or even proceedings of symposia and other thematic issues, under the direction of invited editors, French or foreign.