Mineralogical and geochemical features of karst bauxites from Poci (western Henan, China), implications for parental affinity and bauxitization

The Poci bauxite deposits in western Henan, China, are hosted in the lower member of Upper Carboniferous Benxi Formation, unconformably overlying upon the paleokarst surface of the Ordovician Majiagou Formation. The orebodies comprise a high-grade bauxite horizon (characterized by the association of diaspore-illite-anatase) and a basal iron-rich horizon (diaspore-goethite-hematite-illite-anatase), sandwiched between the overlying clayey layer...