Petrography, and mineralogical and geochemical control on distribution of major, minor, and trace elements in bauxitic-lateritic deposit of the NE Malekan, East-Azarbaidjan Province, NW Iran

The bauxitic-lateritic deposit at northeast of Malekan (East-Azarbaidjan Province, NW Iran) occurred as interlayer horizon within the Ruteh carbonate formation (Middle-Upper Permian). Based on compositional values of major elements, this deposit is divided into four discrete lithologic facies including, (1) laterite, (2) ferruginous bauxite, (3) bauxitic clay, and (4) siliceous bauxite. Petrographically, the ores display pelitomorphic, micro-granular, nodular, pseudo-breccia, colloform, spongy, and collomorphic-fluidal textures which are indicative of an authigenic origin. According to field evidence and geochemical data, the basaltic rocks whose remnants still exist in places adjacent to the lower contact within the carbonate bedrocks are most likely to be the protolith of this deposit. Textural and geochemical studies indicate that besides volume reduction of the protolith and physico-chemical variations (e.g., pH and Eh) within depositional environment during weathering processes, factors such as the availability of the complexing ligands, heterogeneity of the protolith, adsorption, function of carbonate bedrock as geochemical barrier, contemporaneous deposition of elements, existing in the resistant mineral phases, indirect bauxitization, morphological and hydro-dynamical conditions, and finally formation in a passive and undisturbed aqueous environment played important roles in the formation of the bauxitic-lateritic ores in northeast of Malekan.  Correlation coefficients among the elements indicate that trace elements within the ores were fixed by boehmite, diaspore, rutile, anatase, zircon, muscovite, Mn-oxides, and xenotime.