Investigating novel metasomatic processes at the Ilimaussaq Complex, South Greenland

The kakortokites of the Ilimaussaq Complex in South Greenland demonstrate world-class layering in agpaitic nepheline syenites. Each rhythmic layer is sub-horizontal in aspect and considered undeformed since their formation ~1160 Ma ago. They host eudialyte group minerals which contain elements of high economic value (e.g., Zr, Ta, Nb, and rare earth elements). The origin of the layering and mineral enrichment is widely debated. This is further complicated by widespread metasomatic alteration and hydrothermal overprint. The fundamental aim of this PhD project is to constrain whether the macroscale layering can be attributed to magmatic or metasomatic/hydrothermal processes and to what extent this had on the mineral enrichment. The thesis comprises three chapters, respectively focusing on: (1) the petrology and geochemistry of the magmatic, late-stage metasomatic, and hydrothermal phases from within the kakortokites; (2) the geochemical effects of the metasomatic alteration on the mineralogy; and (3) the source of the metasomatic fluids responsible for the alteration using stable isotope geochemistry. This work will further improve our understanding on the formation of layered intrusions and their economically important metal ore deposits.