The Earth’s mantle is divided by the circum-Pacific subduction girdle into the African and Pacific domains, each featuring a large low-shear-wave-velocity province (LLSVP) in the lower mantle. However, how this hemispherical-scale mantle structure links to Earth’s plate tectonic evolution remains unclear. Previous geochemical work has suggested the presence of a north–south hemispheric subdivision, with large-scale mantle heterogeneities in the Southern Hemisphere, termed the DUPAL (Dupré and Allegre) anomaly. Here we compile elemental and isotopic data of both shallow-mantle-derived oceanic igneous rocks from mid-ocean ridges and deeper-mantle plume-related samples (ocean islands and oceanic plateaus) and analyse these using supervised machine learning classification methods. Data from both shallow- and deeper-mantle-sourced samples illustrate a consistent chemical dichotomy. Our results indicate that heterogeneities in the present-day shallow and deep mantle are not exclusively controlled by the north–south hemispheric DUPAL anomaly. Instead, they are consistent with a chemical dichotomy between the African and Pacific mantle domains and their associated LLSVPs. These observations can best be explained by tectonic supercycles over the past one billion years involving two supercontinents and two superoceans.

地幔被环太平洋俯冲带分为非洲和太平洋区域，每个区域在下地幔中都有一个大型的低剪切波速省 （LLSVP）。然而，这种半球尺度的地幔结构如何与地球板块构造演化联系起来仍不清楚。以前的地球化学工作表明，南北半球存在一个南北半球的细分，在南半球具有大规模的地幔异质性，称为 DUPAL（Dupré 和 Allegre）异常。在这里，我们汇编了来自洋中脊的浅地幔衍生的海洋火成岩和更深的地幔羽流相关样品（海洋岛屿和海洋高原）的元素和同位素数据，并使用监督机器学习分类方法对其进行分析。来自浅层和深层地幔来源的样品的数据说明了一致的化学二分法。我们的结果表明，当今浅层和深层地幔的异质性并不完全受南北半球 DUPAL 异常的控制。相反，它们与非洲和太平洋地幔结构域及其相关的 LLSVP 之间的化学二分法一致。这些观察结果可以用过去 10 亿年的构造超级周期来最好地解释，这些现象涉及两个超级大陆和两个超级海洋。