The Konya volcanic belt is located S-SW of the city of Konya (Fig. 2b). It is composed of volcanic domes and ignimbrites of mid-Miocene to Pliocene age (Keller et al., 1977; Temel, 2001). The basement includes Permian metamorphic rocks, Triassic limestone and shales, Jurassic ophiolites, radiolarites, and limestones, and Cretaceous sandstones and quartzites (Temel et al., 1998). The erupted products are andesites to dacites with high-K calc-alkaline affinity. According to K/Ar ages obtained by Keller et al. (1997), a southwestern migration of magmatism is observed with time, starting with the oldest unit, the Sille volcanics (11.45–11.9 Ma), located in the northeastern part of the Konya volcanic and ending with the Fasillar and Gevrekli domes in the SW of the volcanic belt, which show Pliocene ages (3.75 and 3.35 Ma, respectively).

The Konya volcanic belt hosts the Miocene Au epithermal high-sulfidation deposit of Inlice (1.68 t at 2.36 g t Au-1; https://mining-atlas.com, last access: 5 October 2010) and the Miocene–Pliocene Doğanbey Cu porphyry deposit (drilling of 273.90 m at 0.13 g t Au-1; Stratex International Plc, 2018), both shown in Fig. 2b. Two other prospects (Karacaören and the Oğlakçı) have been discovered by Stratex International in the Konya volcanic belt. For details on the mentioned economic deposits, please see Zürcher et al. (2015) for Inlice and Redwood (2006) and Hall et al. (2007) for Doğanbey.

The Usak–Güre basin, situated 300 km west of the Konya volcanic belt, is composed of (i) the Menders Massif, including a metamorphic core composed of metagranites and gneiss (Proterozoic) overlain by Paleozoic schists and Mesozoic marbles, and of (ii) the Upper Cretaceous Ophiolitic mélange of the Izmir–Ankara zone, including unmetamorphosed ultramafic rocks, radiolarites, and altered silicic rocks (Ercan et al., 1978; Çemen et al., 2006). Syn-extensional sedimentation and volcanism associated with the metamorphic complex of the Menders Massif are recorded in detail within the basin. From the early to mid-Miocene, the basin contains three sequences: the Hacibekir Group, the Inay Group, and the Asartepe formation, represented by volcanic and metamorphic rocks (Çemen et al., 2006; Karaoğlu et al., 2010). The Cenozoic volcanism in the Usak–Güre basin occurs in three NE–SW-trending belts wherein the volcanic edifices are aligned. According to the ages obtained by Karaoğlu et al. (2010) and Seyitoglu (1997) it appears that the volcanism migrated from north to south with time: (i) Elmadag (17.29 Ma), (ii) Itecektepe (15.04 Ma), and (iii) Beydagi (12.15 Ma) (see Fig. 2c). Volcanic products include shoshonites, latites, and rhyolitic lavas, followed by dacitic and andesitic pyroclastic deposits. All three volcanoes are composed of dacitic ignimbrites formed by the collapse of their caldera and overlying lava flows.

Among all the volcanic complexes situated in the Usak–Güre basin only the Beydagi complex is mineralised, hosting the Kişladağ Au porphyry (255 t at 0.61 g t Au-1 and 119 t at 0.4 g t Au-1 of total indicated and inferred resources, respectively (Baker et al., 2016), with cut-off grade 0.3 g t-1 and up to 327 ppm of Mo (Sillitoe, 2002); https://www.eldoradogold.com, last access: 30 September 2018).

The Kula volcanic field is situated west of the Usak province (Fig. 2c), and its volcanic products are late Pliocene to late Quaternary in age (Ercan and Oztunali, 1982; Ercan et al., 1983; Richardson-Bunbury, 1996; Innocenti et al., 2005; Aldanmaz, 2002; Westaway et al., 2004). The rocks include lava flows and tephra deposits of varying mafic alkaline composition (basanite, phonolitic tephrite and trachybasalt). Kula represents an intraplate ocean-island-basalt-like (OIB-like) alkali–basaltic volcanic centre with an asthenospheric mantle signature and no subduction-related inputs (e.g. Agostini et al., 2007; Alici et al., 2002; Tokçaer et al., 2005).

The volcanic rocks of the studied areas display a wide range of SiO2 and alkali element concentrations ranging from basalts to andesites–dacites with high-K calc-alkaline to shoshonitic affinity (Fig. 3a, b). The Konya volcanic belt is characterised by volcanic products ranging from andesitic to dacitic in composition with a high-K calc-alkaline affinity. In the Usak basin, the Elmadag volcanic complex is composed mostly of shoshonitic trachyandesites, the Itecektepe volcanic unit is characterised by high-K calc-alkaline rocks, mostly andesitic in composition, and the Beydagi volcanic edifice contains rocks ranging from andesites to trachyandesites with high-K calc-alkaline to shoshonitic affinity. Finally, the Kula Quaternary volcano presents the most alkaline and mafic compositions, ranging from tephrites–basanites to phonotephrites. All rocks present a negative correlation of TiO2 and Fe2O3 with SiO2, with Kula being more enriched in TiO2 and Fe2O3 than the rest.

In terms of trace element concentrations all rocks show a decrease in Cu and Ni with an increase in SiO2 (Fig. 3e–f), indicating a compatible behaviour of these elements during magmatic evolution. In addition, all rocks show an enrichment of light relative to heavy rare-earth elements with decreasing Nb, Ta, and Ni passing from intraplate volcanism (Kula) to post-subduction (Elmadag, Itecektepe, Beydagi, Konya).

All studied samples are volcanic rocks with porphyritic textures. Phenocrysts are usually plagioclase, amphibole, pyroxene (mostly clinopyroxene), and, depending on the volcanic centre, olivine, biotite, and to a lesser extent Fe–Ti oxides (mostly Ti–magnetite). The matrix is aphanitic, mostly composed of microlitic plagioclase (<1 mm) and sometimes amphibole and pyroxene microcrystals. Apatite and anhydrite can also be found as inclusions in pyroxene and Fe–Ti oxide phenocrysts.

Rocks of all study areas contain magmatic sulfides. However, depending on the volcanic centre, sulfides are present in variable amounts, sizes, shapes, and compositions. A comparison of the sulfide occurrences among the different volcanic centres (also corresponding to different geodynamic settings) is given in Fig. 4. In all studied samples sulfides occur inside phenocrysts and not in the groundmass (Fig. 5), with the exception of the Kula volcano that also presents sulfides as aggregates with oxides and micro-sized silicates in the groundmass (Figs. 4e, xi, 5e) and a few cases in Beydagi (Fig. 4xii). The main host phenocryst for sulfides is magnetite for Konya and Beydagi (42 % and 31 %, respectively), amphibole for Itecektepe and Kula (85 % and 39 %), and pyroxene for Elmadag (87 %). Sulfides are also hosted in plagioclase. The common occurrence of voids and/or vesicles in contact with the sulfide phases is noteworthy (e.g. Figs. 4v, vii, x, 5g, 6i, f).

Based on petrographic observations and SEM mineral analysis we distinguished six main types of magmatic sulfides: (1) Type 1 sulfides containing two to three distinct phases, namely a Cu-poor and Ni-rich phase (pyrrhotite), an Ni-rich phase (pentlandite), and rarely a Cu-rich phase (cubanite) (Fig. 4a); (2) Type 2 sulfides containing two to four distinct phases, namely a Cu-poor (pyrrhotite), one to two Cu-rich (chalcopyrite ± cubanite), and sometimes an Ni-rich (pentlandite) phase (Fig. 4b); (3) Type 3 sulfides containing a Cu-rich phase (chalcopyrite or chalcocite) and an Fe-rich phase (pyrite/Fig. 4c); (4) Type 4 sulfides containing only Cu-rich phase(s) (chalcopyrite, ± cubanite, ± bornite), occasionally in contact with anhydrite (Fig. 4d); and (5) Type 5 sulfides containing aggregates of a Cu-poor and Ni-rich (pyrrhotite) sulfide phase and one or more Al-rich oxide phases (magnetite, magnetite–ilmenite, and secondary goethite) (Fig. 4e). Finally, Type 6 sulfides, the so-called “daughter sulfides” (e.g. Savelyev et al., 2018; Fig. 5h), were only observed in three cases in this study within olivine phenocrysts of rocks from Kula. From SEM analysis this latter sulfide type it is composed only of pyrrhotite ± pentlandite; however, due to their small size (<0.5 µm) they could not be analysed with the EPMA.

Type 1 sulfides are only hosted by olivine; they are generally small (<30 µm), round, and show pentlandite exsolution flames in pyrrhotite (Fig. 4i). Type 2 sulfides, the most common, are hosted by different phenocrysts (pyroxene, amphibole, magnetite, and plagioclase), presenting a range of sizes (up to 70 µm) and having mostly ellipsoidal to rounded shape (Fig. 4ii–vii). The pentlandite phase in this sulfide type can occur either as an exsolution in the pyrrhotite and/or as an individual phase inside the Ni-rich pyrrhotite (Fig. 4vi), whereas cubanite is mostly present when the sulfide is hosted in amphibole, forming complex exsolution textures with chalcopyrite and presenting irregular rounded–resorbed shapes (Fig. 5d). Type 3 and 4 sulfides are only hosted by magnetite phenocrysts occurring in smaller sizes (<30 and <20 µm) and presenting ellipsoidal and angular shapes, respectively (Fig. 4viii, ix, x). Type 4 sulfides have been observed in some cases in contact with anhydrite and with zircon inclusions (usually <20 µm) all hosted by the same magnetite crystal (Fig. 6). Finally, Type 5 consists of sulfide aggregates with variable size (up to 600 µm), which may carry rounded oxide inclusions and are sometimes in sharp contact with surrounding silicate phases (Figs. 4xi, xii, 5e). Although all study areas present Type 2 sulfides, from the volcanic centres situated in the Usak basin, only Beydagi shows sulfide Type 3 and 5, whereas only Kula and Konya present sulfide Type 1 and 4, respectively.

Electron microprobe analysis of single mineral phases composing a multiphase sulfide inclusion confirms the above petrographic observations and SEM analysis. Sulfides belonging to Konya and to the volcanic areas of the Usak–Güre basin (Beydagi, Elmadag, and Itecektepe) have compositions typical of the Cu–Fe–S system, whereas sulfides observed in Kula (intraplate OIB-like volcanism) extend into the Cu–Fe–Ni system as well (Fig. 7a, b). Sulfides from all areas present a range of compositions between pyrrhotite and cubanite–chalcopyrite (Type 2 and 5) hosted by different phenocrysts (mostly amphibole, pyroxene, and magnetite; Fig. 7a). Beydagi shows additional compositions between chalcopyrite (sometimes chalcocite) and close or equal to magmatic pyrite (Type 3), and Konya presents sulfides ranging from chalcopyrite to bornite compositions (Type 4). The latter types are only hosted by magnetite. In the case of Kula, Type 1 and some Type 2 sulfides are Ni-rich, ranging from pyrrhotite to pentlandite (Fig. 7b). A general decrease in the sulfide Ni/Cu ratio versus the Fe/S ratio can be noted, switching from Ni-rich sulfide phases (pentlandite) hosted by olivine to Cu-rich (bornite) hosted by magnetite (Fig. 7c).

EPMA sulfide compositions often correspond to the variable nonstoichiometric atomic ratios of major components different from the typical expected base metal composition of the sulfide phase observed, resulting in intermediate values characteristic of a solid solution, mostly between two endmembers (e.g. cubanite, chalcopyrite, and bornite; Figs. 6, 7). In addition, in some cases sulfides are characterised by a sulfur deficiency, which, according to previous studies, may be a result of the replacement of sulfur by oxygen that is not directly measured by EPMA (e.g. Larocque et al., 2000; Keith et al., 1997). These latter cases usually show lower totals than those resulting from Cu-rich Type 4 sulfide analysis (see Table 4 from Georgatou and Chiaradia, 2019).

A sulfide comparison for each area in terms of Cu and Ni contents, determined by EPMA, is shown in Fig. 8. Konya presents the most Cu-rich sulfides (Type 4, Cu median = 56 wt %) and Kula the most Ni-rich sulfides (Type 1, Ni median = 4.2 wt %). In the Usak basin Beydagi shows the most Cu-rich sulfides (Type 3, Cu median = 32 wt %), followed by Elmadag (Type 2, Cu median = 0.14 wt %) and then by Itecektepe (Type 2, Cu median = 0.03 wt %). In addition to Cu, Fe, Ni, and S, sulfides were also analysed for As, Se, Zn, Ag, and Au (see Table 2 in Supplement S2 for determination limits.). For all locations As and Se are generally lower than 0.1 wt %. Zn concentrations were obtained only for Konya and Kula, showing, for Type 2 sulfides, Zn median = 0.03 wt % and 0.04 wt %, respectively. Out of 503 Ag and 196 Au sulfide measurements obtained, only 82 and 31 values, respectively, resulted in concentrations above the detection and/or determination limit. Ag varies between 0.01 wt % and 0.07 wt % with a maximum amount of 0.11 wt % (in Konya), whereas Au is higher, showing higher values in the Usak–Güre basin (Au median = 0.14 wt %–0.24 wt %) compared to the rest (Au median = 0.04 wt %–0.05 wt %). These unusually high sporadic values of Ag and Au have been attributed by previous studies to the clustering and nugget effects of noble metals (e.g. Savelyev et al., 2018; Zelenski et al., 2017; Holwell et al., 2015; Holwell and McDonald, 2010). A possible Au nugget occurrence is shown in Fig. 4viii for Type 3 sulfides of Beydagi. Although the phase is too small (<0.5 µm) to obtain quantitative values by EPMA, detectable Au was measured by SEM near and on this high-reflectance micro-phase.

Since sulfide inclusions of all types are composed of more than one mineral phase (e.g. pyrrhotite and chalcopyrite), the sulfide composition data are presented and discussed in two different ways: (a) as individual microprobe measurements of mineral phases within each multiphase sulfide type from the different study areas (Table 1, Figs. 7, 8) and (b) as bulk compositions of the sulfide inclusion reconstructed by considering the modal abundance (area %) and the EPMA concentrations for each phase composing the multiphase sulfide (see Table 2, Figs. 9 and 10, and examples of the reconstruction methods in Supplement S2).

Calculating the area percent occupied by each mineral composing the sulfide in the two-dimensional space (and therefore the mss/iss initial proportions) allows us to obtain indirect quantitative information on the initial metal contents of the silicate melt from which the sulfide melt was exsolved in the different study areas. This is because the areas characterising the mss and iss phases are proportional to the metal amounts that have partitioned into these phases. Whereas this approach may yield biased results due to cut effects, crystal orientation and other limitations of this method (see Supplement S2) averaged out over a large number of sulfide inclusions, so we think we have obtained a significant 1st-order estimate. The mean proportions of mss and iss in area percent are shown in the box plot in Fig. 9 and Table 2. The mss area percent (mss/(mss+iss)⋅100) and 2 standard errors for each study area are as follows: Kula (82.0±7.4 %), Itecektepe (84.8±4.9 %), Elmadag (86.9±4.8 %), Beydagi (86.9±3.2 %), and Konya (88.1±2.6 %). A reconstruction of the bulk mss and iss in area (%) composition of the sulfides was also realised in this study for the case of Ecuador for comparative purposes, resulting in an mss area percent of 82.0±4.8. When Type 2 sulfides from all investigated areas for a total of 126 sulfides are considered together, all study areas present similar proportions of Fe-rich mss (84.2 %) and Cu-rich iss (15.7 %) phases within error (2 se = ±2.2).

The evolution of sulfide melt has been studied through experiments considering sulfide globules as closed systems that differentiate with decreasing T (e.g. Kullerud et al., 1969; Cabri, 1973; Naldrett and Gasparrini, 1971; Cabri, 1973; Craig and Scott, 1974; Tsujimura and Kitakaze, 2004; Holwell and McDonald, 2010; Naldrett, 2013, and references therein). Nonetheless, there is difficulty to correlate the different phase stability fields for the complete range of temperatures, i.e. 1200–100 ∘C. This is due to the fact that the Fe–Ni–Cu–S system is a complex system characterised by a number of solid solutions and unquenched phases. In addition, the mineral assemblage composing the sulfides depends, among other factors (fO2 and fS2), on the initial metal budget of the silicate melt and therefore on the metal contents of the exsolving sulfide melt, as well as on the P and T conditions under which this melt solidifies. A compilation of isothermal sections of the Cu–Fe–S system resulting from a number of experimental studies realised at different temperatures is presented in Fig. 10. For this study it is important to note at which approximate temperature intervals mineral phases can coexist, and therefore a summary of the experimental findings, only focused on the mineral phases observed in this study, is presented below.

The general agreement is that above 1200 ∘C the system is composed of a metal-rich (Cu, Au) liquid and a sulfur-rich (+Fe, Ni) liquid (Craig and Kullerud, 1969). An Fe, Ni-rich, Cu-poor monosulfide solid solution (mss) and a Cu, Au-rich, Ni-poor intermediate solid solution (iss) exsolve at around 1192 ∘C (Jensen, 1942) and 960 ∘C (Kullerud et al., 1969), respectively (Fig. 10a–b and c). The pair mss–iss is stable only starting from 935 and until 590 ∘C (Fig. 10c–e), below which these two phases cannot coexist. At around 930 ∘C a high-temperature bornite solid solution (bnss-h) and iss become stable (Fig. 10c). With further cooling (∼610 ∘C; Fig. 10e) the mss converts to pyrrhotite (po) through the exsolution of a high-temperature pentlandite (pn–h) (e.g. Stone et al., 1989). Subsequently, at 590 ∘C the iss unmixes into chalcopyrite (cp) and cubanite (cb) (Fig. 10f; e.g. Yund and Kullerud, 1966). Pyrite (py) appears at 743 ∘C and becomes stable with iss at 739 ∘C and with cp at 600 ∘C (Fig. 10e). The pair cp–py coexists until at least 200 ∘C (Craig and Scott, 1974). A low-temperature pentlandite (pn) appears at 610 ∘C and becomes stable with cp at 572 ∘C. Finally, the bnss-h breaks down to a chalcocite (cc–bnss) and digenite (dg–bnss) bnss pair at 430 ∘C (Fig. 10g). At 334 ∘C pyrrhotite becomes stable with chalcopyrite, and with further cooling at 330 ∘C the digenite–bnss pair breaks down to digenite and bornite (bn; Fig. 10g–h).

Two main stages of sulfide evolution were observed in this study, confirming the experimental temperature range windows for specific mineral pairs as well as conclusions from previous research (Hattori, 1996; Parat et al., 2011; Du et al., 2014; Agangi and Reddy, 2016). The first stage accounts for the more primitive sulfide types (Type 1 and 2) including mss-rich ± iss and mss + iss sulfide melt, now represented by compositions (shown from individual mineral analysis in Fig. 7 and reconstructed area compositions in Fig. 10) close to pyrrhotite (± pentlandite, cubanite) and pyrrhotite + chalcopyrite (± cubanite), respectively. Their shape (round–ellipsoidal) and host mineral (olivine for Type 1 and amphibole, pyroxene, plagioclase, and magnetite for Type 2) confirm their origin as Fe–Ni-rich (± Cu) sulfide melts. The second stage consists of Type 4 sulfides, characterised by an iss-only and Cu-rich sulfide liquid (as all the Ni has been exhausted), which now comprises chalcopyrite and bornite (± digenite). This sulfide type occurs only within Fe oxides, mostly in Ti-rich magnetite displaying occasional ilmenite exsolution lamellae. Their angular shape indicates that the solution was trapped initially as a Cu-rich liquid (Chang and Audétat, 2018) which solidified into an iss following the host mineral crystallisation planes and later unmixed (see also Georgatou et al., 2018; Holwell et al., 2015). In addition to the relatively low temperature ranges compared to the first stage sulfides (<330 ∘C; see Fig. 10), other petrographic and compositional arguments for considering this a later stage are the following: (i) the unique occurrence in magnetite, a late crystallising mineral relative to olivine and pyroxene (hosting the first stage sulfide Type 1 and 2), and (ii) the more common occurrence of voids and/or vesicles around the Cu-rich sulfides accounting for higher mean portions of the inclusions (up to 23 area %, with up to 19 area % for Type 4 and 14 area % for Type 3; see Fig. 6 and Table 5 in Georgatou and Chiaradia, 2019) compared to Type 2 sulfides (<5 area %). The contact between each sulfide inclusion and these vesicles is smooth, indicating that these voids could account for a pre-existing fluid phase which exsolved from the silicate melt before entrapment in the magnetite crystal (Table 2).

Sulfide Type 3 and 5 are more difficult to interpret. Type 3 presents both ellipsoidal and rectangular shapes, indicating entrapment as a liquid. The temperature range that corresponds to the mineral assemblage of chalcopyrite (± chalcocite) + pyrite is 600–200 ∘C, suggesting a later timing than the first-stage sulfides. Finally, Type 5 sulfide aggregates are similar to the first-stage sulfides (Type 2) and seem to have originated from an mss- and Fe-rich system, producing immiscibility textures of the rounded oxide inclusions into the pyrrhotite, which have later aggregated with silicates.

In this study, no early and late sulfides cohosted by the same mineral were observed. This suggests two distinct sulfide saturation stages, during which the system has to undergo magnetite crystallisation to reach the second stage. However, it is still not clear whether these stages are indeed distinct and independent of one another or if they may directly follow one another through a continuous process of sulfide saturation, whose products change chemistry due to the chemical evolution of the melt. Nonetheless, according to the sulfide types observed in these two stages, the Ni/Cu (proxy for mss/iss) decreases with magmatic evolution (Fig. 7c), starting from an mss-rich sulfide melt (Type 1), followed by an mss and iss melt (Type 2 and 5), and finally (and uniquely for some settings) by iss-rich, iss-only sulfides (Type 3 and 4). Although this decrease in Ni/Cu has been noted previously by other researchers (e.g. Hattori, 1996; Du et al., 2014; Keith et al., 2017; Savelyev et al., 2018), for the early sulfides, until now there has not been a systematic study of the later-stage, iss-only sulfides. The reason for this is most likely the fact that the majority of past studies on sulfides have focused on silicate mineral separates in order to be able to locate and analyse the bulk chemistry of entrapped sulfides. This not only prevents necessary observations on textural mineral relations but also the study of nontransparent to opaque minerals, which, as was shown here, host Cu-rich and iss-only sulfides.

Volcanic rocks from all study areas contain sulfides and therefore have reached magmatic sulfide saturation at some stage during the lifespan of the magmatic system; however, there are significant textural and compositional differences, which are described below.

Beydagi shows slightly more enriched (though similar within error) Cu values in Type 2 sulfide (Cu median = 0.3 wt %) than Elmadag (Cu median = 0.14 wt %) and Itecektepe (Cu median = 0.03 wt %). Additionally, the area (%) of the Cu-phase iss of Type 2 sulfides found in Elmadag (17.2±4.8), Itecektepe (14.7±4.9), and Beydagi (13.1±3.2) is similar. However, although in terms of bulk chemistry there are not major differences between the three volcanic centres (mostly andesites to trachyandesites), Beydagi is the only volcanic centre within the Usak basin which is characterised by two other sulfide types (Type 3 and 5) and at the same is the only mineralised volcanic centre. Implications regarding the ore fertility of these systems will be discussed in the following section. Relative to the other investigated areas of western Anatolia, sulfides in Beydagi show no pentlandite but in some cases present chalcopyrite (± chalcocite) coexisting with pyrite. This suggests that the iss-rich exsolving sulfide melt was Cu-rich relative to Kula but Cu-depleted relative to Konya.

Various Miocene large Cu–Mo ± Au porphyry deposits (e.g. Junín–Llurimagua Cu–Mo deposit and the Cascabel Cu–Au-rich deposit) occur in the frontal arc of Ecuador. Available data on whole rocks indicate that mineralisation is spatially and temporally associated with high-Sr/Y porphyritic stocks (Schütte et al., 2012). Investigation of these rocks under a reflected petrographic microscope confirmed previous observations from Schütte et al. (2012) that the rocks contain abundant hydrothermal sulfides, rendering these samples inadequate for the scope of the present study. For this reason, Georgatou et al. (2018) investigated fresh volcanic rocks from the Quaternary arc of Ecuador. These are intermediate to felsic calc-alkaline magmatic rocks with high Sr/Y values erupted through a crust with a thickness ranging from 50 to 70 km (Feininger and Seguin, 1983; Guillier et al., 2001). Such features are similar to those of magmatic systems typically associated with large porphyry Cu deposits (Loucks, 2014; Chiaradia and Caricchi, 2017), and the temporal and spatial proximity of Miocene deposits to the Quaternary arc rocks investigated lend support to the possibility that processes leading to the formation of porphyry-type deposits under the Quaternary arc of Ecuador could be currently ongoing. Therefore, the Quaternary arc rocks of Ecuador can be used as a proxy for a potentially fertile syn-subduction magmatic environment.

In the Quaternary volcanics, Georgatou et al. (2018) observed that magmatic sulfides occurred in all studied rocks (from basalt to dacite) of the volcanic arc as polymineralic inclusions composed of Fe-rich, Cu-poor, and/or Cu-rich phases, occurring mostly in Fe/Ti oxides and to a lesser extent in silicate minerals. Only sulfide Type 2 and 4 were observed in Ecuador, presenting a remarkable textural and compositional resemblance to the case of Konya. Rocks from both areas display first-stage (Type 1 and 2) and second-stage (Type 4) sulfide saturation. In particular, according to EPMA, in individual mineral analyses of 19 sulfides in Konya and 22 in Ecuador, Cumax⁡ ranges between 72 wt % and 66 wt %, respectively.

Georgatou et al. (2018) suggested that the negative trend of Cu with magmatic differentiation (e.g. Keith et al., 1997; Chiaradia, 2014) observed in typical syn-subduction magmatic arcs is a result of a continuous Cu sequestration in magmatic sulfides. A similar Cu decrease with magmatic evolution is also observed in the areas studied here and characterised by post-subduction magmatic rocks, some of which are also associated with porphyry and epithermal-type deposits. This suggests that in both settings (syn-subduction and post-subduction) Cu and other chalcophile metals behave compatibly during magmatic evolution and confirms that these metals are lost on the way to the surface.