Magmatic architecture and evolution of the Mesoproterozoic nested layered mafic intrusions of the Tantalite Valley Complex, southern Namibia

Renewed interest in the Tantalite Valley Complex has uncovered PGE-enriched magmatic sulphides. Despite this, little is known about the internal stratigraphy of the complex. This study aims to rectify this paucity of research by investigating the internal stratigraphy and architecture of the TVC. These aims have been achieved through field mapping, petrographic, geochemical, and isotopic studies from an extensive and representative sample set. These techniques have shed light on the magmatic evolution of the study site, and the complex is interpreted to be a composite of three to four nested intrusions. The nested intrusions are overwhelmingly mafic and are layered in nature, in contrast to earlier interpretations in the literature. Additionally, these intrusions have undergone limited differentiation, where geochemical evidence reveals cryptic layering reversals interpreted to reflect open system magmatic recharge. Isotopic evidence supports these interpretations and underpins an interplay involving time, magma replenishments, tectonism, and the establishment of new magma chambers that ultimately formed the complicated stratigraphy of the Tantalite Valley Complex. This study highlights the convoluted evolution of this intrusion during the Namaqua orogeny, having regional implications for the evolution of several similar intrusions in the surrounding area and indeed across global orogenies where mafic-ultramafic bodies exist. The following highlights can be drawn from this research: • The Tantalite Valley Complex is a composite of three to four nested intrusions. • These intrusions are stratiform and layered. • Several magma replenishments are recorded.