Since the 1970s, ferromagnetic minerals were believed to be absent in the Earth’s mantle and, even if present, the temperatures were considered too high for such phases to carry magnetic remanence. However, new experimental data, measurements on mantle xenoliths and an improved understanding of long-wavelength features in aeromagnetic data require that the magnetization of the mantle be revisited. In this Review, we examine mantle magnetism through the xenolith record, evaluate the latest experimental advances, assess detection methods of deep-seated mantle sources and identify salient, unsolved questions about magnetic sources in the Earth’s mantle. Critically, magnetic data on a worldwide collection of mantle xenoliths have revealed that pure magnetite is common in the uppermost mantle (<150 km), particularly in subduction zones and cratons. Furthermore, experiments on haematite and its polymorphs suggest that they could carry a magnetic remanence down to ~600 km, for example, in cold, subducted slabs. Finally, modern spectral analysis of aeromagnetic data confirms that a magnetized layer is present below the crust–mantle boundary in multiple tectonic settings. Future work needs to explore the magnetic minerals in the deepest available mantle xenoliths (150–660 km), in conjunction with experiments on mantle materials at pressures corresponding to these depths.

自1970年代以来，据信地球地幔中不存在铁磁性矿物，即使存在，人们也认为温度太高，以至于这些相无法携带剩磁。但是，新的实验数据，对地幔异岩的测量以及对航空磁数据中长波特征的更好理解要求重新考虑地幔的磁化强度。在本综述中，我们将通过异种岩记录检查地幔磁性，评估最新的实验进展，评估深层地幔源的检测方法，并确定有关地球地幔中磁源的突出但尚未解决的问题。至关重要的是，有关全球范围内地幔异岩的磁性数据表明，纯磁铁矿在最上层地幔（<150 km）中很常见，特别是在俯冲带和克拉通中。此外，对赤铁矿及其多晶型物的实验表明，它们可以在例如冷的俯冲板中携带低至600 km的剩磁。最后，对航空数据的现代频谱分析证实，在多个构造环境中，地壳-地幔边界以下存在磁化层。未来的工作需要探索可用的最深地幔异种岩（150-660 km）中的磁性矿物，并在与这些深度相对应的压力下对地幔物质进行实验。