## 5 Discussion  
### Conditions of Formation of the Porphry Cu-Au Deposit at Gerakario  
The porphyry Cu-Au deposit and the epithermal quartz-stibnite veins at Gerakario are related to the emplacement of a syenite intrusion in two-mica gneiss of the Vertiskos unit during the Miocene (22 \(\pm\) 0.8 Ma; U-Pb zircon ages [42]), in an extensional structural  
Figure 8: Histogram showing the homogenization temperatures of the fluid inclusions from the porphyry (Types 1, 2, and 3) and the epidermal system (Type 1) at Gerakario. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Mineralization Style**} & \multirow{2}{*}{**FI Type**} & \multirow{2}{*}{**Th (\({}^{\circ}\)C)**} & \multirow{2}{*}{**Tm (Ice) (\({}^{\circ}\)C)**} & \multicolumn{1}{c}{**Salinity**} \\  & & & & **(wt.\% NaCl equiv.)** \\ \hline \multirow{2}{*}{\
\begin{tabular}{c} Porphry style quartz \\ veins (A-type) \\ \end{tabular} } & 1 L + V \(\rightarrow\) L & 382 to 496 (\(n\) = 34) & \(-\)19.4 to \(-\)10.8 (\(n\) = 6) & 14.8 to 22.0 \\  & 2 L + V + S \(\rightarrow\) L & 381 to 458 (\(n\) = 27) & 271 to 386 (\(n\) = 27) & 35.7 to 45.6 \\  & 3 L + V \(\rightarrow\) V & 382 to 504 (\(n\) = 33) & \(-\)16.5 to \(-\)11.9 (\(n\) = 6) & 14.4 to 19.8 \\ \hline \multirow{2}{*}{
\begin{tabular}{c} Epithermal style \\ quartz-stibnite veins \\ \end{tabular} } & 1 L + V \(\rightarrow\) L & 256 to 326 (\(n\) = 75) & \(-\)6.9 to \(-\)5.0 (\(n\) = 12) & 7.9 to 10.4 \\ \hline \hline \end{tabular} Abbreviations: FI = Fluid inclusions; L = liquid aqueous phase; V = vapor phase; S = solid phase (halite, sylivite); Th = homogenization temperature; Tm (ice) = final ice melting temperature; \(n\) = number of microthermometric analyses.  
\end{table} 
Table 3: Microthermometric data from the different types of fluid inclusions in the porphyry and epithermal systems at Gerakario. regime. The mineralization shares many similarities in its geotectonic setting, structural control, magma evolution, hydrothermal alteration, and physicochemical parameters of the hydrothermal fluids with the adjacent Vathi porphyry-epithelial system, which is genetically related to a quartz monzonite [32; 33]. At Gerakario, the fast ascension of the syenite magma and its crystallization at shallow depths caused exsolution of hydrous fluids and silicate melts that resulted in hydraulic fracturing, increasing the permeability of the host rocks. This mechanism favored the formation of the potassic hydrothermal alteration and the deposition of the Cu-Au mineralization in the A-type veins, along fractures, under boiling conditions. Phase separation was favored by a rapid drop in temperature and pressure in the veins, resulting in a saline brine (36-46 wt.% NaCl equiv.) and a co-existing lower salinity (14-22 wt.% NaCl equiv.) low-density vapor-rich fluid that homogenize over the same temperature range, between 380\({}^{\circ}\) and 460 \({}^{\circ}\)C (Figure 9). According to [PERSON] et al. [58], aqueous fluid inclusions with moderate salinity (up to 20 wt.% NaCl equiv.) represent a fluid extracted from the magma. In this case, the fluid is cooled to conditions between plastic and brittle deformation, creating inclusions enriched in the liquid (Type 1) and vapor phases (Type 3) at Gerakario, with moderate salinity, without forming liquid inclusions with halite [58]. The densities of the hydrothermal fluids at the Gerakario porphyry deposit are \(>\)0.90 g.cm\({}^{-3}\) for the fluids with high salinity (type 2 fluid inclusions) and \(<\)0.78 g.cm\({}^{-3}\) for the moderate salinity fluids (type 1 and 3 fluid inclusions). The trapping pressures of the fluid inclusions can be estimated considering that the fluids were trapped under boiling conditions in the system NaCl-KCl-CaCl\({}_{2}\)-H\({}_{2}\)O. Based on homogenization temperatures and the equation of Archer [59], the minimum trapping pressures for type 2 inclusions in A-type quartz veins range from 100 to 350 bar, and for type 3 inclusions from 240 to 580 bar.