Complex REE systematics of carbonatites and weathering products from uniquely rich Mount Weld REE deposit, Western Australia

Carbonatite intrusive complexes are important hosts for Rare Earth Elements (REE) deposits and commonly affected by surficial weathering processes. Mount Weld REE deposit of Western Australia is one the world’s richest here we present whole-rock mineral geochemical data on compositions primary weathered carbonatites. The concentrations in magmatic carbonatites at vary two orders magnitude, suggesting a significant role processes enrichment carbonatite complex. Th-Pb age 2056±67 (2?) Ma monazite-(Ce) from obtained situ LA-ICP-MS analyses confirm Paleoproterozoic mineralization. regolith samples preserve detailed record evolution to products intensive weathering. silica-cemented (silcrete) contains apatite chemically identical their carbonatite-hosted equivalents. high-REE containing 51.8 wt% ?REE2O3 has some highest found date, negative Ce anomaly lithogenic monazite within matrix florencite-(Ce) rhabdophane-(Nd) tubes resembling casts plant material. pronounced anomalies ferruginous cap rock (ferricrete) indicate weathering, where Ce4+ was preferential removed relative REE3+. presence paleo-plants implicates bio-assisted involved extreme fractionation. diverse processes, which occurred supergene environment Weld, have implications understanding genesis worldwide.