Hydrothermal alteration, stable isotope geochemistry and 3D GIS modelling of maden village (Bayburt) Cu-Au (?) mineralization

Maden village (Bayburt) Cu-Au (?) alteration field which is located in southern zone of Eastern Pontide Tectonic Unit is related to trachy-andesites called as "Maden Andesite". The Upper Cretaceous trachy-andesites are mostly concentrated in the area of trachy-andesite and andesite in the chemical nomenclature diagram Nb / Y vs Zr / TiO2 x 0.0001, according to the AFM triangle diagram, the rocks have calc-alkali character, in SiO2- K2O and Th-Co comparison diagrams, it was determined that the samples mostly fall into the high potassium-shoshonitic calc-alkali series area. Alterations occurring in Upper Cretaceous trachy-andesites are as follows; sulfurization, limonitization, malachitization, azuritization, silicification and hematitization. Alteration types are shown on three-dimensional GIS modeling. As a result of the MINSQ calculations, as alteration minerals quartz K-feldspar, ± albite were determined in the ore zone; and Fe-chlorite, Mg-chlorite and epidote were determined in propylitic zone. According to the relative mass change calculations, MgO, TiO2, K2O, Na2O, MnO, Cu, Ag, Pb and Mo values showed a relative increase, while Fe2O3, SiO2, CaO, Al2O3, Zn, As, Cu and Au show relative decrease in the ore zone. When the relations between the elements causing the relative mass increase or decrease are examined, it is determined that there is a negative relationship between serizitization and mineralization; silicification, mineralization and hematitization take place together; and while the hematitization forming the plagioclase decomposition occurs. The values of MgO, K2O, CaO, Na2O, Ag, Cu, Pb and Mo showed net mass increase in ore zone due to net mass change calculations; whereas SiO2, Fe2O3, Al2O3, Zn, As and Au showed a decrease in net mass. The δ18O and δ2H isotope values of the sericite mineral ranges from ‰ 6.4-12.5; and ‰ -116 to -99, respectively. This change in isotope results indicates a mixture of magmatic and meteoric water at the origin of ore-forming solutions.