Chromite compositions in nickel sulphide mineralized intrusions of the Kabanga-Musongati-Kapalagulu Alignment, East Africa: Petrologic and exploration significance

摘要: Abstract Chromite is a ubiquitous accessory mineral in the olivine-pyroxene cumulate bodies that host massive and disseminated nickel sulphide mineralization intrusions of Kabanga-Musongati-Kapalagulu Alignment East Africa. Its composition related to conditions emplacement petrologic evolution its magma spectrum ranging from classical lopolithic layered groups smaller, discrete sill-like chonoliths. The Kapalagulu intrusion, emplaced into polymetamorphosed Archaean-Palaeoproterozoic crust, contains abundant chromite with relatively oxidized compositions, whereas chromites highly-mineralized Kabanga chonolith intrusions, graphitic sulphidic schists, are strongly reduced terms their Fe 3+ /Fe total ratio. Ni correlates olivine: both depleted more sulphide-mineralized intrusions. Musongati also through but much larger less-well mineralized sulphides than Kabanga, has intermediate character. compositions can be used determine history may prove useful exploration tool such belts.