We present the first global review on the Sm-Nd and Lu-Hf isotope systematics of the mantle; it includes all published data on peridotites and pyroxenites from all tectonic settings (>1100 combined Hf-Nd analyses), as well as previous compilations for oceanic basalts and material such as oceanic and continental sediments. We first provide a comprehensive overview of the main reservoirs and mechanisms accounting for the contrasting variability of radiogenic isotope systematics in the sub-oceanic mantle and the relative homogeneity of its volcanic products, highlighting the paradigm change promoted by the use of Hf isotopes. Secondly, we summarize the different models invoked to explain the decoupling/(re-)coupling of Hf and Nd isotopes. Decoupling above the mantle array is often related to melt-peridotite interaction involving ancient protoliths, whereas coupled Hf-Nd or decoupling below the array are shown to be insufficient criteria to exclude the involvement of such protoliths. The Hf-Nd isotope variability of the SCLM is then addressed using a tectono-thermal classification based on the Global Lithospheric Architecture Mapping (GLAM) project. The extreme variability that characterizes the cratonic SCLM reflects the long-term preservation of depleted signatures overprinted by ancient and recent metasomatic episodes. Refertilized SCLM domains fingerprinted by variably decoupled Hf-Nd isotope systematics record subduction-related processes, which also appears to be instrumental in the recycling of continental material into the convective mantle. We show that there is a critical “chicken-and-egg” question underpinning debates on the spatio-temporal evolution of the SCLM: whether ancient signatures are pre-existing in the lithosphere (e.g. “lithospheric memory” during refertilization) or introduced into the convective mantle (i.e. recycling). Importantly, our compilation shows that fertile lithologies such as pyroxenites can also carry extremely depleted isotopic signatures. In particular, delamination of gravitationally unstable, pyroxenite-rich arc roots represents a volumetrically significant flux of material characterized by ancient radiogenic Hf and basalt-like Nd-isotope compositions that can, once recycled, account for the Hf variability observed between MORB suites. In this context, the characteristic HIMU-like or coupled Hf-Nd signatures observed in garnet-pyroxenite layers from orogenic peridotite massifs probably reflects long-term processing (re-coupling) of recycled lithospheric material in the convective mantle. In contrast, continental dispersal during rifting (± plume-related processes) appears to be mostly limited to buoyant SCLM remnants in the oceanic lithosphere, and these are unlikely to be recycled unless previously refertilized. This work brings a new geodynamic perspective to the ancient signatures identified as chemical and isotopic heterogeneities in the oceanic lithosphere and convective mantle. These conclusions imply that (1) subduction is the main driver of mass transfer between lithosphere and asthenosphere and (2) the long-term evolution of the Earth's mantle and crust are directly linked to convergent plate-tectonic processes, at least since the Archean.

我们提出了关于地幔 Sm-Nd 和 Lu-Hf 同位素系统学的第一个全球综述；它包括来自所有构造环境的所有已发表的橄榄岩和辉石岩数据（>1100 次 Hf-Nd 组合分析），以及以前对海洋玄武岩和海洋和大陆沉积物等材料的汇编。我们首先全面概述了主要储层和机制，这些储层和机制解释了亚洋地幔中放射性同位素系统学的对比变异性及其火山产物的相对均匀性，强调了使用 Hf 同位素促进的范式变化。其次，我们总结了用于解释 Hf 和 Nd 同位素的去耦/（重新）耦合的不同模型。地幔阵列上方的解耦通常与涉及古代原石的熔体-橄榄岩相互作用有关，而阵列下方的耦合 Hf-Nd 或去耦合显示不足以排除此类原石的参与。然后使用基于全球岩石圈结构映射 (GLAM) 项目的构造热分类来解决 SCLM 的 Hf-Nd 同位素变异性。克拉通 SCLM 的极端可变性反映了古代和近期交代事件叠印的耗尽特征的长期保存。由可变解耦的 Hf-Nd 同位素系统学指纹识别的再肥化 SCLM 域记录了与俯冲相关的过程，这似乎也有助于大陆物质循环进入对流地幔。我们表明，有一个关键的“鸡与蛋”问题支撑着关于 SCLM 时空演变的辩论：例如再受精期间的“岩石圈记忆”）或引入对流地幔（即回收）。重要的是，我们的汇编表明，辉石岩等肥沃的岩性也可以携带极度贫化的同位素特征。特别是，重力不稳定、富含辉石岩的弧根的分层代表了一种体积上显着的材料通量，其特征在于古代放射性 Hf 和玄武岩类 Nd 同位素组成，一旦回收，就可以解释 MORB 套件之间观察到的 Hf 变异性。在这种情况下，在造山带橄榄岩地块的石榴石-辉石岩层中观察到的特征性 HIMU 样或耦合 Hf-Nd 特征可能反映了对流地幔中循环岩石圈材料的长期加工（重新耦合）。相比之下，裂谷过程中的大陆扩散（±羽流相关过程）似乎主要限于海洋岩石圈中的浮力 SCLM 残余物，除非先前重新施肥，否则这些残余物不太可能被回收。这项工作为海洋岩石圈和对流地幔中被确定为化学和同位素异质性的古代特征带来了新的地球动力学视角。这些结论意味着（1）俯冲是岩石圈和软流圈之间质量转移的主要驱动力，（2）地幔和地壳的长期演化与会聚板块构造过程直接相关，至少自太古宙以来是这样。这项工作为海洋岩石圈和对流地幔中被确定为化学和同位素异质性的古代特征带来了新的地球动力学视角。这些结论意味着（1）俯冲是岩石圈和软流圈之间质量转移的主要驱动力，（2）地幔和地壳的长期演化与会聚板块构造过程直接相关，至少自太古宙以来是这样。这项工作为海洋岩石圈和对流地幔中被确定为化学和同位素异质性的古代特征带来了新的地球动力学视角。这些结论意味着（1）俯冲是岩石圈和软流圈之间质量转移的主要驱动力，（2）地幔和地壳的长期演化与会聚板块构造过程直接相关，至少自太古宙以来是这样。