Quartz textures, mineral chemistry and fluid inclusion features of Tuztaşı low-sulphidation Au mineralization: Implication to it's formation

The Tuztaşı gold mineralization, within the Main Quartz Vein (MQV), is located within the amphibolite schist of the Sütüven Formation along a structural zone trending K50D. The vein is inclined approximately 40° to the northeast, exhibits a thickness ranging from 3 to 8 m with 2 km lenght. Gangue minerals within the vein primarily consist of quartz, chalcedony, and opal. In MQV, crustiform, feathery, colloform textures indicating boiling and massive chalcedony, comb, textures in restricted zones, as well as replacement textures and brecciation in later stages have been identified.

In the amphibolite, the host rock around the MQV, while weak argillic alteration developed represented by quartz, montmorillonite, kaolinite mineral associations, this alteration is surrounded by propylitic alteration represented by quartz, albite, orthoclase, chlorite, calcite, and ankerite mineral associations.

LA-ICP-MS studies on quartz of the MQV revealed the gold values up to 4.02 ppm and silver values reaching 100 ppm, predominantly enriched in secondary voids (vugs) and iron-rich fracture zones. SEM-EDX analyses of gold-bearing quartz have identified chromite, chalcopyrite, native platinum, and Ni-Fe-Cr alloy, suggesting interactions with ore-forming fluids potentially originating from the mafic-ultramafic levels of the Sütüven Formation and Çetmi Melange.

Fluid inclusion studies show that liquid-rich inclusions dominate in MQV, but vapour-rich inclusions also occur together in genetically. According to microthermometric data, Th values of quartz vary between 186 and 330 °C, but the majority of the data (89 %) fall within the 180–260 °C range (aver. 213 °C, n = 104). The salinity of the fluids ranges from 0.18 % to 2.74 %, with an average of 0.63 % wt. NaCl equivalent. The dominant temperature range (180–260 °C) corresponds to a salinity of 0.35 wt% NaCl equivalent. An average Th (221 °C) and salinity (0.63 % wt. NaCl equivalent) values are resemble typical of low-sulphidation gold deposits.

Oxygen isotope (δ¹⁸O) data of quartz from the MQV, ranging between 6.6 ‰ and 8.6 ‰, indicating a meteoric origin for the fluids. This is indicated by the δ¹⁸O_SMOW values of waters in equilibrium with quartz, falling between δ¹⁸O_water − 6.8 ‰ and 0.7 ‰.

Collevtively, fluid inclusions, oxygen isotope data, quartz textures in MQV and alteration features are evaluated together, the Tuztaşı Au mineralization exhibits the characteristics of a low-sulphidation type Au deposit rather than an orogenic type Au deposit.