Molybdenum isotope systematics of lavas from the East Pacific Rise: Constraints on the source of enriched mid-ocean ridge basalt
Molybdenum isotope systematics of lavas from the East Pacific Rise: Constraints on the source of enriched mid-ocean ridge basalt
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东太平洋海隆熔岩钼同位素系统学：对富集洋中脊玄武岩来源的限制
DOI：
10.1016/j.epsl.2021.117283
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发表时间：
2021-11
影响因子：
5.3
通讯作者：
Remco C.Hin
中科院分区：
文献类型：
--
作者：
Shuo Chen;Pu Sun;Yaoling Niu;Pengyuan Guo;Tim Elliott;Remco C.Hin
洋中脊玄武岩（MORB）揭示了大的地幔成分的不均匀性，其起源仍然存在争议。在这里，我们提出了一个系统的钼同位素研究的特点MORB玻璃样品从东太平洋海隆（EPR）和近EPR海山。我们的分析显示了显著的Mo同位素变化，δ 98/95 Mo（相对于NIST SRM 3134）范围为− 0.23‰至− 0.06‰。我们认为，这些钼同位素的变化不是由MORB熔体的生成和演化过程，但反映地幔同位素的不均匀性。结合文献资料，我们发现MORB的Mo同位素组成与指示地幔富集的地球化学参数有系统的变化。这些观察结果最好用不相容元素耗尽端元之间的双组分混合来解释（如La/Sm、Nb/La、Nb/Zr和Th/Yb低，Sm/Nd和143 Nd/144 Nd高），δ 98/95 Mo低（ε-0.21 ‰）和不相容元素富集端元（例如，高La/Sm、Nb/La、Nb/Zr和Th/Yb，低Sm/Nd和143 Nd/144 Nd），高δ 98/95 Mo（δ-0.05 ‰）。较重的钼同位素组成与地球化学更丰富的MORB的协会是不一致的，与循环洋壳或没有沉积物富集的端元。相反，这是一致的富集端元岩浆起源，最有可能的岩性低度熔融交代起源分散在更耗尽的橄榄岩基质中的MORB地幔。因此，与MORB钼同位素系统学，我们证实，再循环的海洋地幔岩石圈交代的低度熔融起着关键作用的E-MORB源岩性的形成。我们的研究还强调了钼同位素作为研究上地幔过程的有效工具。
Mid-ocean ridge basalts (MORB) reveal large mantle compositional heterogeneity, whose origin remains debated. Here we present a systematic study of molybdenum isotopes on well-characterized MORB glass samples from the East Pacific Rise (EPR) and near-EPR seamounts. Our analyses show significant Mo isotope variations with δ 98/95 Mo (relative to NIST SRM3134) ranging from− 0.23‰ to− 0.06‰. We argue that these Mo isotope variations are not caused by processes of MORB melt generation and evolution but reflect mantle isotopic heterogeneity. Taking together with the literature data, we show that MORB Mo isotope compositions vary systematically with geochemical parameters indicating mantle enrichment. These observations are best explained by two-component mixing between an incompatible element depleted endmember (eg, low La/Sm, Nb/La, Nb/Zr and Th/Yb, and high Sm/Nd and 143 Nd/144 Nd) with low δ 98/95 Mo (∼− 0.21‰) and an incompatible element enriched endmember (eg, high La/Sm, Nb/La, Nb/Zr and Th/Yb, and low Sm/Nd and 143 Nd/144 Nd) with high δ 98/95 Mo (∼− 0.05‰). The association of heavier Mo isotope compositions with the geochemically more enriched MORB is inconsistent with recycled ocean crust with or without sediment being the enriched endmember. Instead, this is consistent with the enriched endmember being of magmatic origin, most likely lithologies of low-degree melt metasomatic origin dispersed in the more depleted peridotite matrix in the MORB mantle. Thus, with MORB Mo isotope systematics, we confirm that recycled oceanic mantle lithosphere metasomatized by low degree melt plays a key role in the formation of E-MORB source lithologies. Our study also highlights Mo isotopes as an effective tool for studying upper mantle processes.
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影响因子：
3.9
作者：
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通讯作者：
Vadim Kamenetsky;S. Eggins
影响因子：
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作者：
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作者：
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影响因子：
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作者：
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通讯作者：
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