Platinum group elements mineralogy of late proterozoic podiform chromitites from the Eastern Desert of Egypt: A preliminary result

摘要

Platinum-group elements (PGE) mineralization has been recently reported in podiform chromitites from the late Proterozoic Pan-African ophiolite of the Eastern Desert of Egypt. The identified major platinum-group minerals (PGM) in decreasing abundance are as follows: sulphides, sulpharsenides, alloys and arsenides. PGM Sulphides are the most common minerals in the central Eastern Desert chromitites, while Os-Ir alloy is predominant in the southern Eastern Desert ones. The most abundant base metal sulphides (BMS) in the Eastern Desert chromitite of Egypt are millerite, heazlewoodite, pentlandite, chalcopyrite and pyrite. The combination of PGE mineralogy and Os-isotope data of the Os-rich PGM suggest that the mantle rocks of this ophiolite are possibly representative of lithosphere produced or modified in a subduction setting.