Identifying potential porphyry Cu mineralization at the Kirazlı district in Biga Peninsula (NW Turkey): Insights from the mapping hydrothermal alteration by using shortwave infrared (SWIR) spectrometry

The Kirazlı mineral district is located at the center of the Biga peninsula metallogenic province, in a geological setting characterized by an extensional tectonic environment. The district hosts a high-sulfidation (HS) ore body with a total reserve of 33.86 Mt @ 0.69 g/t Au and 9.42 g/t Ag within a large-scale hydrothermal alteration. Although the ideal magmatic-hydrothermal models present the spatial and temporal association of HS-epithermal and porphyry Cu deposits, the porphyry Cu potential at the Kirazlı has not been evaluated, yet. Therefore, the mineral-based alteration mapping with the help of SWIR reflectance spectroscopy was carried out. Our study demonstrates that nine different mineral zone have been distinguished and mapped: (1) Silicification, (2) Alunite, (3) Kaolinite, (4) Dickite, (5) Illite, (6) Pyrophyllite, (7) Chlorite, (8) Sericite, and (9) Montmorillonite zones. Collectively, these alterations exhibit a zoned pattern, from central massive silicification to residual silica, NW-SE oriented alunite, and marginal montmorillonite-illite zones within widespread kaolinite – dickite dominated alteration in Kirazlı main zone. The occurrence of pyrophyllite and sericite dominates at the SE of the Kirazlı district, which refers to relative temperature increase. Subsequent drilling confirms the potential for deep prospecting of porphyry Cu mineralization in the region.