<b>Lithospheric relamination and disruption of mantle carbon during supercontinent cycle</b><b>s</b>

<b>Carbon exchange between Earth’s surface and its deep interior surely occurs but evidence is scant and the processes are poorly understood. Although isotopes and mineral inclusions from eclogitic diamonds suggest deep recycling of crustal material, the fate of subducted carbon, specifically whether it can </b><b>survive deep subduction</b><b> to relaminate with the continental lithosphere and therefore be accessible to later cratonic magmatism, remains unclear. </b><b>Here we demonstrate</b><b> a coupled relationship between the C and Nd isotopes of mantle-derived carbonate-rich magmas, carbonatites and kimberlites, where both isotopes for both rock types consistently fluctuate between more or less mantle-derived carbon and magmatism. T</b><b>ime series analysis of these datasets further reveals</b><b> statistically significant cycles</b><b> </b><b>of ~</b><b>500 and ~250 million years, corresponding to supercontinent and Wilson cycles, respectively</b><b>. Exploring a possible mechanism, we perform geodynamic modelling that demonstrates that carbonate sediment may subduct beyond sub-arc depth and ascend to the overlying cratonic lithosphere, providing a carbon source for kimberlite and carbonatite magmatism. The</b><b> periodic</b><b>ity of </b><b>kimberlites and carbonatites, revealed by their C and Nd isotopes,</b><b> stems from, as supported by our modelling, the subduction of carbonate sediment and its relamination onto cratonic keels during supercontinent assembly, then its disruption and incorporation in kimberlite and carbonatite magmatism during supercontinent breakup.</b>地球表层与深部内部之间的碳交换无疑真实存在，但相关证据匮乏，且对相关过程的认知程度极低。尽管来自榴辉岩型金刚石的同位素与矿物包裹体证据表明地壳物质发生了深部循环，但俯冲碳的最终归宿——尤其是其能否在深俯冲过程中留存，进而与大陆岩石圈再堆叠并为后续克拉通岩浆作用所利用——仍不明晰。本研究揭示了幔源富碳酸盐岩浆、碳酸岩与金伯利岩的碳（C）与钕（Nd）同位素之间的耦合关系：两类岩石的两种同位素均在近似幔源碳与岩浆成因的端元间持续波动。对该数据集的时间序列分析进一步揭示了两组具有统计学显著性的周期：分别约为5亿年与2.5亿年，对应超大陆旋回与威尔逊旋回。为探究潜在机制，本研究开展了地球动力学模拟，结果表明碳酸盐沉积物可俯冲至弧下深度以下，并上涌至其上覆的克拉通岩石圈，从而为金伯利岩与碳酸岩岩浆作用提供碳源。通过碳与钕同位素揭示的金伯利岩与碳酸岩的周期性，源于本研究模拟所佐证的过程：超大陆聚合阶段，碳酸盐沉积物发生俯冲并再堆叠至克拉通根；超大陆裂解阶段，这些碳被改造并融入金伯利岩与碳酸岩的岩浆作用中。