Geophysical Research Letters
Geophysical Research Letters
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Magnetism as a Proxy for Sedimentary Rare Earth Element Enrichment in the Eastern Pacific Ocean and Its Potential Use for Identifying Deep Ocean Rare Earth Element
Abstract Rare earth elements and yttrium are critical for advanced technological and environmental applications. Rare earth element-enriched deep-sea sediments have attracted attention as significant potential rare earth element resources. However, efficient identification of these deposits in the open oceans is a persistent challenge. From integrated chemical leaching experiments and geochemical and rock magnetic analyses of two Eastern Pacific Ocean sediment cores, we find a coupled evolution between magnetic signatures and rare earth element concentrations in sediment profiles. Apatite and iron-manganese oxyhydroxides are the primary rare earth element carriers, while biogenic magnetite dominates the magnetic mineral assemblage. We elucidate here mechanistic linkages between mineral magnetic signals and rare earth element enrichment, demonstrating their shared dependence on deep-sea productivity cycles and redox dynamics. We propose that systematic magnetic property analyses could serve as a novel geophysical proxy for identifying rare earth element-rich sediment in marine environments.
Plain Language Summary Rare earth elements and yttrium are essential for modern technology, from smartphones to renewable energy systems. These valuable elements can be found in deep-sea sediments, but efficient identification of these deposits in the open oceans remains challenging. In this study, we examined sediment samples from the Eastern Pacific Ocean and discovered that magnetite produced by bacteria dominates the magnetic mineral assemblage in rare earth element-enriched sediments, where apatite and iron-manganese oxyhydroxides are the primary rare earth element carriers. Our data suggest that productivity governs formation of both apatite and magnetofossils and drives rare earth element enrichment via liberation of phosphorus, iron, and rare earth elements during organic matter remineralization. Coupling of biogenic magnetite and apatite in sediment profiles implies that magnetic properties could be used to identify oceanic rare earth element-rich sediments.