Abstract Accurate knowledge of the composition of Earth’s major chemical reservoirs is fundamental for constraining all modern geochemical cycles. Basaltic rocks provide a direct way of sampling the composition of Earth’s inaccessible interior. Here, we present the first comprehensive neodymium (Nd) stable isotope analyses for a global compilation of mid-ocean ridge, ocean island, continental intraplate and island arc basalts using a double-spike technique. In these primitive magma compositions magmatic differentiation has no resolvable effect on δ146/144Nd. Mid-ocean ridge basalts possess an extremely homogenous δ146/144Nd with an average composition of δ146/144Nd = −0.025 ± 0.013 ‰ (± 2 s.d.; n = 33). Ocean island and continental intraplate magmas possess more variable compositions (δ146/144Nd = 62 ppm) that are related to the variable incorporation of recycled components in their source regions. Island arc basalts from New Britain (δ146/144Nd = 61 ppm) reflect the complex interplay between source composition, degree of melting and slab-fluid inputs. Variations are uncorrelated with indicators of magmatic differentiation or slab-fluid addition, rather increasing δ146/144Nd with slab depth is attributed to a higher proportion of metasomatized sub-arc mantle in the melting region. A partial melting model for Nd stable isotopes has been constructed using Nd−O force constants calculated using the Born-Lande approximation. Melting of typical mantle peridotite will induce no resolvable fractionations of Nd stable isotopes (Δ146/144Ndmelt-mantle

中文翻译：

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从大洋中脊、洋岛和弧形玄武岩推断地球球粒状钕稳定同位素组成

摘要 准确了解地球主要化学储层的组成是限制所有现代地球化学循环的基础。玄武岩提供了一种对地球难以接近的内部成分进行采样的直接方法。在这里，我们使用双尖峰技术对大洋中脊、海洋岛屿、大陆板内和岛弧玄武岩的全球汇编进行了首次全面的钕 (Nd) 稳定同位素分析。在这些原始岩浆成分中，岩浆分异对 δ146/144Nd 没有可分辨的影响。大洋中脊玄武岩具有极其均匀的 δ146/144Nd，平均成分为 δ146/144Nd = -0.025 ± 0.013 ‰ (± 2 sd; n = 33)。海岛和大陆板块内岩浆具有更多的可变成分（δ146/144Nd = 62 ppm），这与其源区中回收成分的可变结合有关。来自新不列颠的岛弧玄武岩 (δ146/144Nd = 61 ppm) 反映了源成分、熔融程度和板片流体输入之间复杂的相互作用。变化与岩浆分异或板块流体添加指标无关，δ146/144Nd随着板块深度的增加而增加，归因于熔融区交代亚弧地幔的比例较高。已经使用使用 Born-Lande 近似计算的 Nd-O 力常数构建了 Nd 稳定同位素的部分熔化模型。典型地幔橄榄岩的熔化不会导致 Nd 稳定同位素 (Δ146/144Ndmelt-mantle 来自新不列颠的岛弧玄武岩 (δ146/144Nd = 61 ppm) 反映了源成分、熔融程度和板片流体输入之间复杂的相互作用。变化与岩浆分异或板片流体添加的指标无关，而δ146/144Nd随板片深度的增加归因于熔融区交代亚弧地幔的比例较高。已经使用使用 Born-Lande 近似计算的 Nd-O 力常数构建了 Nd 稳定同位素的部分熔化模型。典型地幔橄榄岩的熔化不会导致 Nd 稳定同位素 (Δ146/144Ndmelt-mantle 来自新不列颠的岛弧玄武岩 (δ146/144Nd = 61 ppm) 反映了源成分、熔融程度和板片流体输入之间复杂的相互作用。变化与岩浆分异或板片流体添加的指标无关，而δ146/144Nd随板片深度的增加归因于熔融区交代亚弧地幔的比例较高。已经使用使用 Born-Lande 近似计算的 Nd-O 力常数构建了 Nd 稳定同位素的部分熔化模型。典型地幔橄榄岩的熔化不会导致 Nd 稳定同位素 (Δ146/144Ndmelt-mantle 变化与岩浆分异或板片流体添加的指标无关，而δ146/144Nd随板片深度的增加归因于熔融区交代亚弧地幔的比例较高。已经使用使用 Born-Lande 近似计算的 Nd-O 力常数构建了 Nd 稳定同位素的部分熔化模型。典型地幔橄榄岩的熔化不会导致 Nd 稳定同位素 (Δ146/144Ndmelt-mantle 变化与岩浆分异或板片流体添加的指标无关，而δ146/144Nd随板片深度的增加归因于熔融区交代亚弧地幔的比例较高。已经使用使用 Born-Lande 近似计算的 Nd-O 力常数构建了 Nd 稳定同位素的部分熔化模型。典型地幔橄榄岩的熔化不会导致 Nd 稳定同位素 (Δ146/144Ndmelt-mantle