## 7 Discussion
### Source of Metals  
Phase separation promotes Au deposition in porphyry systems, which follows the deposition of Cu at high temperatures [76; 77]. In addition, Au precipitation in phreatic breccias is favored by the permeable textures created by the periodic catastrophic release of the build-up of volatiles [56]. This could also be the case for the Au enrichment during the formation of the Vathi breccia (724 ppb Au). At Vathi, gold is also related to the oxidized D-type veins, which occur in the sericitic alteration (6996 ppb Au). A similar relationship between high Au contents and D-type mineralized veins was reported by [PERSON] et al. [78], where gold is found as inclusions in pyrite in the Pagoni Rachi Cu-Mo-Re-Au deposit in northern Greece.  
Molybdenum at Vathi was precipitated near and below a depth of 166 m after Cu was precipitated, while Fe, Pb, Zn, and As are enriched in the upper, outer, and adjacent areas of the quartz monzonite and was related to the epithermal stage. [PERSON] [16], based on Pb isotope compositions, has shown that the enrichment of Cu, Pb, and Zn at Vathi is associated with crustal rocks assimilation from magma.  
The quartz-monzonite and latite at Vathi are enriched in Sr (Vath 41: 1269.1 ppm, Vath 42: 1173.2 ppm), Rb (Vath 41: 165.3 ppm, Vath 42: 120.1 ppm), and Ba (Vath 41: 1513.8 ppm, Vath 42: 867.8 ppm) (Table 2). These elements are lithophile and incompatible in the mantle, and the enrichment of these elements could be related to differentiation of the parental magma and the subsequent interaction with crustal rocks, as well as to the onset of significant plagioclase fractionation [79; 80]. In this regard, Sr values are considered more enriched, with respect to reported values from intermediate to evolved magmas (<100 ppm) [80]. Moreover, the enrichment in high field strength elements (HFSE; Zr, Hf, Nb, and Ta) is likely the result of limited assimilation of crustal rocks as the magma differentiated [79].  
A significant enrichment is also observed in the REE: La (up to 613.1 ppm), Ce (up to 894 ppm), Pr (up to 79.1 ppm), Nd (up to 211.1 ppm), and Gd (up to 12.7 ppm), as well as in Ti (up to 7040 ppm) and P (up to 1340 ppm) (Table 2). These geochemical anomalies could suggest that the Vathi deposit shares several characteristics in common with alkaline igneous rock-related porphyry deposits [81].  
Uranium exhibits moderately to highly enriched concentrations in the magmatic rocks in the Vathi area (14 to 106 ppm). In the phreatic breccia and along the mineralized tectonic structures, the high U content (up to 328 ppm) is manifested by the presence of autunite-group minerals, torbernite and meta-torbernite. Uranium enrichment is rather an uncommon characteristic of porphyry systems associated with calc-alkaline igneous rocks [82]. On the contrary, U tends to be enriched in porphyry deposits related to alkaline intrusions [82; 83].  
At the Vathi area, the enrichment in U was likely associated with the final stages of crystallization of the mildly alkaline magma combined with movement along deep-seated faults. Rupturing of the intrusive cupola was likely associated with fluid exsolution and the accumulation of a magmatic fluid enriched in U. Fluid exsolution was favored by deep-seated faults, while a network of fractures enhanced rock permeability resulting in the formation of secondary torbernite. [PERSON] et al. [83] described a similar mechanism that resulted in the enrichment of U in the alkaline igneous rock-related porphyry molybdenum system at Central City, Colorado.