The geological investigates of the manganese depositions within the Koçali melange (Adiyaman-Çelikhan)

The deposits (Çağalalı and Bezardağı) in the study area, outcropped in the Koçali Melange, was trusted over Arabian platform in the Southeast Anatolian Orogenic Belt during Upper Cretaceous, are located to the North of Koçali village in Adıyaman. In the study area, the basement consists of radiolarian cherts (Konak formation) and spilitic pillow lavas (Tarasa formation) which belong to allochtonous Koçali Melange, settled as a result of tensile sliding. In the upper part of the succession the Germav Formation has moderate thickness and the Gercüş Formation discordatly lies on to the Koçali Formation. The Midyat Formation consisting Nummilitic limestones was formed on all these units.Mineralizations are oriented along E-W/30N direction and appear as irregular lenses. They are alternately bedded and are concordant with the wall-rocks. The ore paragenesis is; pyrolusite, psilomelane, manganite. The grain sizes of the ore minerals are variable; they are mainly massive and formed as crack fillings.Whole rock geochemistry of the the mineralizations (MnO: 8.98%-73.64%, SiO2: 3.26%-86.19%) are akin to the ocean floor hydrotermal deposits. The Fe/Mn ratio of the represantative samples, varying between 0.001 and 0.019 are too low. The Fe/Mn ratios are similar to the deposits formed at the ocean floor centers with a rapid precipitation velocity. The 18O isotop analyzes on the ore samples yield higher values than SMOW, indicating enrichment by hydrothermal liquids accompanying volcanism. Ore minerals are populated at the hydrotermal areas in the diagrams made for major and trace elements.