Chapter 5 Tectonic Setting of Proterozoic Layered Intrusions with Special Reference to the Bushveld Complex

Abstract

Publisher Summary Layered intrusions are a feature of several tectonic environments and are known from the oldest greenstone belts of the Yilgarn, Zimbabwe, and Kaapvaal Cratons to the tertiary layered intrusives associated with continental rifting, such as Skaergaard and Rhum. These intrusions are of great economic significance as they host virtually all the world's resources of the platinum-group elements and chromite as well as important deposits of vanadium, Cu, and Ni. Consequently, many of these intrusions have been studied in great detail. Most of these investigations, however, have focussed on magma chamber crystallization processes to explain igneous layering and associated mineralization. Recently, interest has shifted somewhat to questions concerning the tectonic setting of layered intrusions and the source regions of their parental magmas. In this chapter, the more important Proterozoic layered complexes are discussed in terms of their tectonic setting, postulated parental magmas, and internal stratigraphy to evaluate whether a correlation exists among tectonic setting, intrusion form, and the source of parental magma for the more important Proterozoic layered intrusions.