A comparison of the fenites at the Chilwa Island and Kangankunde carbonatite complexes, Malawi

Abstract

Carbonatites are igneous carbonate rocks. They are the main source of the rare earth elements (REE) that are essential in low carbon and high technology applications.Exploration targeting and mine planning would both benefit from a better understanding of the processes that create the almost ubiquitous alkaline and rare earth (RE)-bearing metasomatic aureoles in the surrounding country rocks.Using SEM-based analysis and whole rock geochemistry, we investigated the composition and mineralogy of the fenite aureoles developed around the RE-poor Chilwa Island carbonatite and the RE-rich Kangankunde carbonatite, which intrude similar country rocks in the Chilwa Alkaline Province of Southern Malawi. Although common characteristics and trends in their mineralogy and composition may be typical of fenites in general, there are significant differences in their petrography and petrogenesis. For instance, the mineralogically diverse breccia at Kangankunde contrasts with the intensely altered