Investigation of immobile elements geochemistry of Permo -Triassic bauxitic horizon at west of Miandoab

Category Environmetal Geology
Group GSI.IR
Location 23th symposium on geosciences
Holding Date 05 May 2008

      Bauxitic horizon of west of Miandoab is located in south of West-Azarbaidjan province. This stratiform horizon lies along the boundary of Permian carbonates and Triassic shales and limestones. The upper Permian uplift exposed the pre-Permian rocks to moderate to strong weathering and lateritization. Based upon field evidence and petrographic studies, five bauxitic facies are recognized within this horizon. Chemical data and correlation coefficient show that Al, Ti, Zr, and Nb acted as immobile elements during bauxitization processes. Mass change calculations of elements in the bauxitic units indicate that bauxitization resulted in progressive desilication, hydration, and distinct vertical separation of Al and Fe in the residual weathered horizon and in leaching out of alkali and earth alkali metals from the system. Based upon ratios of immobile elements, the diabasic rocks in the area are the principal source for bauxitic horizon of west of Miandoab and 17 to 42 meters of it was consumed during weathering and bauxitization processes. Combination of obtained data from geochemistry of immobile elements and mineralogy of diabasic parent rock indicate that buaxitization in the west of Miandoab resulted from oxidation of pyrite and break-down of minerals such as olivine, augite, feldspar, ilmenite and apatite.