Vertical migration of residual magma in the upper zone of the Bushveld Complex

摘要: Migration of residual liquid can potentially affect the textures and mineral compositions in layered intrusions, but is difficult to conclusively demonstrate. In Upper Zone Bushveld Complex a metabasaltic xenolith forms locally impermeable horizon, which acted as barrier vertically migrating residua. Increased Ab content plagioclase, K2O Zr whole-rock analyses anorthosite directly below xenolith, compared same horizon along strike demonstrate trapping and/or fluid beneath xenolith. Comparison Cu/Ni Cu/S ratios mineralised normal sequence suggests that these are primary magmatic sulphides crystallised within not derived by sinking dense interstitial sulphide originally associated with overlying magnetite layer or introduced hydrothermally.