Carl Spandler, Andrew Merdith, Amber Griffin
Continental intraplate magmatism through time has played a crucial role in ancient mass extinctions, landscape evolution, global climate, and volcanism. These magmatic systems are also crucial sources of critical metals, including the rare earth elements (REEs). Nonetheless, the origins of alkaline intraplate magmas, such as carbonatites, remain enigmatic. Here, we use kinematic plate modeling to show that ~35% of the present-day subcontinental lithospheric mantle has experienced substantial subduction-related fertilization in the past 2 billion years. These fertilized mantle domains underlie ~67% of post-1.8-billion-year-old carbonatites and ~72% of magma-related REE ore deposits (and ~92% of Precambrian REE deposits), substantiating a genetic link between the ancient, enriched mantle lithosphere and alkaline intraplate magmatism and associated ore deposits. We find no correlation between the timing of mantle source fertilization and carbonatite formation, indicating that the evolution of these magmas is multistage, including an initial metasomatic "primer" of the mantle lithosphere and a subsequent and disconnected melting "trigger" event responsible for magma generation.