Geophysical and geochemical characterization of apatite mineralization on Mlindi Ring Structure

Abstract

The geochemical and magnetic data of the Mlindi Ring Structure has been used to understand the full extent of the rare earth and base metal mineralization hosted in the apatite-rich meta-pyroxenite and other mafic to ultra-mafic rocks. Previous studies in Mlindi Ring Structure had only focused on understanding the agro-minerals economic potential from the apatite. However, this study’s combination of geochemical and geophysical analyses of the Mlindi Ring Structure has identified it as a possible multicommodity deposit. The Ring Structure contains considerable anomalous values for gold, zinc, nickel copper and rare earth elements. The mineralization of gold and base metals is found in almost all the lithologies but much higher in apatite-bearing meta-pyroxenite. On the other hand, rare earth elements are mostly associated with dark rocks i.e. meta-gabbro and meta-pyroxenite and less in silica-rich rocks like quartzofeldspathic gneisses. The soil thickness in Mlindi Ring Structure makes it difficult to understand the full mineralization in the rocks underneath it as very few outcrops are present. We combined the geochemical results with the aeromagnetic data analyses to estimate the full extent of the magnetic minerals which make the core of the Ring Structure using its susceptibility and depth estimates. Pyroxenite, meta-gabbro and biotite-rich mafic rocks show some apatite mineralization with a larger percentage in the meta-pyroxenite rather than the other mafic rocks.