Rare earth element mineralizations in the Palabora Carbonatite Complex

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Carbonatites represent the most important source for REE, which play a key role for many modern, especially green technologies. Therefore, the detailed understanding of where and how carbonatite-related REE deposits form is critical to mineral exploration and future development of these important resources. This project will systematically investigate the so-far barely documented REE mineralization of the Palabora Carbonatite Complex (PCC) in South Africa. The PCC is a perfectly suited research object to answer important questions concerning carbonatite-related REE mineralizations because of its mineralogicaly variable and multi-stage REE-mineral assemblages and the unique possibility to systematically investigate mineralogical changes with respect to REE-minerals over a vertical distance of about 1500 m. Detailed petrography, EMPA and LA-ICP-MS work will be performed to track spatial variations in the textural and compositional evolution of the various REE-mineral assemblages. Whole-rock analyses, including high quality REE data, will be carried out by XRF and ICP-MS, which will allow for identifying chemical variations through the complex. Characterization of fluid inclusions (microthermometry, Raman spectroscopy, gas chromatography-IRMS) will be combined with stable isotope data for rock-forming minerals, which will allow for deciphering the various fluid sources involved in the formation and remobilization of the various REE mineralizations. The results of this study will enhance our knowledge concerning the emplacement and the magmatic to hydrothermal evolution of carbonatitic systems and their associated REE mineralization with depth, including potential changes in physico-chemical parameters (e.g., P, T, pH, fO2, aH2O, aCO2, aHF, aHCl) and changing fluid sources, which may have direct consequences on the type of REE-mineral assemblage.