Textural and genetic investigations of gold mineralization in fault-controlled quartzcarbonate veins in Bayburt-Zarani area (Eastern Pontides-NE Turkey)

Authors: NECATİ TÜYSÜZ, GÜLTEN YAYLALI ABANUZ, OĞUZHAN GÜMRÜK, BAHRİCAN AR

Abstract: The Eastern Pontides Orogenic Belt (EPOB), geographically corresponding to the northeastern part of Turkey hosts several different types of mineralizations that are closely related to Late Mesozoic-Early Cenozoic arc magmatism. Of these, Zarani gold mineralization, which is located in the southern part of the EPOB occurs as quartz-carbonate veins/veinlets within the Pulur metamorphic massif of Paleozoic age. Mineral textures indicate low-temperature vein-type mineralization. Gold mainly occurs in quartz and pyrite. The presence of calcite, dolomite, and sericite in the mineralization indicates near neutral pH conditions of ore-forming fluid. Geochemical analyses of chlorites in the quartz-carbonate veins reveal a temperature of ore formation at 140-297 °C, which is compatible with those obtained from fluid inclusions in the mineralized quartz (i.e. 132-226 °C). The average salinity value obtained from fluid inclusions is 4.32% NaCl equiv. O and H isotope values range from -6.03 °C to +1.47 °C and from -60 °C to -119 °C, respectively, indicating a mixture of magmatic and meteoric fluids. Mixing is also evidenced by the XFe analytical data of hydrothermal chlorites associated with ore-forming gangue minerals. Gold precipitation in Zarani mineralization is caused by boiling. The occurrence of mineralization within quartz-carbonate vein/veinlets in metamorphic host rocks, the mineral paragenesis with near-neutral pH conditions of the ore-forming low salinity fluids and the H-O isotopic data imply that the Zarani gold mineralization is an orogenic type epithermal mineralization that may be related to deeply buried Early Cenozoic felsic intrusions, produced by subduction-induced processes in the southern part of the EPOB.

Keywords: Eastern Pontides Orogenic Belt, epithermal gold, vein-type, stable isotope, fluid inclusion

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