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Generalized geological map of Lesvos Island and the location of the Stypsi prospect (modified after Pe-Piper et al., 2019).
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The Stypsi Cu-Mo-Au-Re prospect, Lesvos island, a shallow porphyry-epithermal system hosted within a middle Miocene microgranite porphyry, was emplaced along NNE-, NW-and NE-trending structures, within trachyan-desites to trachydacites and felsic pyroclastics of the Stypsi caldera. The mineralization comprises three stages: Stage I is characterized...
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... kilometers to the north of the Stypsi prospect, epithermal-style quartz-fluorite-calcite veins crosscutting trachyandesites host economic intermediate (IS)-low (LS)-sulfidation Pb-Cu-Au-Ag mineralization, particularly the Megala Therma deposit ( Kontis et al., 1994; Fig. 1). According to Kontis et al. (1994), this mineralization is the fossil equivalent of a present day active geothermal system in northern Lesvos, whose surface indication is the hot spring in the Megala Therma ...
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... and comprises early to middle Miocene volcanic rocks of shoshonitic to calc-alkaline affinity (Pe-Piper, 1980a,b;Piper, 1992, 1993) that overlie the metamorphic Paleozoic-Mesozoic basement which belongs to the Sakarya Zone of the Rhodope-Pontide Fragment (Hecht, 1974;Hatzipanagiotou and Pe-Piper, 1995;Pe-Piper et al., 2001;Koglin et al., 2009) (Fig. ...
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... 2013). Lesvos island lies in the western extension of the NE-trending Edremit graben, in the southern part of Biga Peninsula, Turkey (Bonev and Beccaletto, 2007;Sanchez et al., 2016). Three major calderas (e.g., Stypsi, Mesotopos and Vatoussa) were described on Lesvos island by Piper (1992, 1993), Rokos et al. (2000) and Vamvoukakis et al. (2005) (Fig. 1). ...
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... 9 km to the north of Stypsi, the Megala Therma Pb-Zn-Ag-Au-Te epithermal deposit (Fig. 1) developed at the periphery of the Stypsi caldera ( Kontis et al., 1994;Voudouris and Alfieris, 2005). Host rocks for the mineralization at Megala Therma is a propylitically altered hornblende-biotite trachyandesite, which belongs to the Lower Lava Formation of Lesvos island ( Kontis et al., 1994). Mineralization is associated with ...
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... ore correlation diagrams reveal positive correlations between Au versus Ag, Au versus Mo, Mo versus Re and Mo versus Cu (Fig. 10). In the last two diagrams, samples that plot outside these trends, may reflect different mineralization stages and/or variable degrees of ...
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... as inclusions or rims on pyrite (Fig. 9i), rarely molybdenite-pyrite veins crosscut sericitically altered rock, overprinted by argillic alteration (Fig. 7b). Molybdenite in Stages I and II contains up to 0.3 wt and up to 1.9 wt% Re, respectively (Table 5). However, Re can vary by more than 1 wt%, within the same molybdenite crystal from Stage II (Fig. 11a-c), which is similar to the variable composition observed by Voudouris et al. (2009Voudouris et al. ( , 2013) in molybdenite from other porphyry deposits in northern Greece. This heterogeneity is most likely due to the inhomogenous distribution of nano-sized particles of rheniite (ReS 2 ) throughout the crystal. Representative electron ...
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... observed by Voudouris et al. (2009Voudouris et al. ( , 2013) in molybdenite from other porphyry deposits in northern Greece. This heterogeneity is most likely due to the inhomogenous distribution of nano-sized particles of rheniite (ReS 2 ) throughout the crystal. Representative electron microprobe compositions for molybdenite are plotted in Fig. 11d. 14 Table 4 Trace element content of porphyry style mineralization (samples ST12A-DST32), silicic and advanced argillic alteration (samples ST22-STAL4) and intermediate sulfidation epithermal veins at Stypsi (LSST4, ST16). Values are in ppm except for Au, Ag, Re, Pd and Pt, which are in ppb. Galena surrounds pyrite in substage I C and ...
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... inclusions were studied in quartz from the porphyry transitional and banded quartz veins and the IS epithermal veins at Stypsi. The D-type and HS epithermal chalcedony veins did not contain fluid inclusions. At Stypsi, early quartz in the veins is characterized by anhedral grains (Fig. 12a). They are mainly equigranular and demonstrate a polygonal shape. These characteristics are common in early quartz veins in many porphyry copper systems and imply that the quartz has been extensively recrystallized ( Monecke et al., 2018). Subgrain rotation and grain boundary migration due to several pulses of fluid flow and the ...
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... recrystallization, which destroys most of the fluid inclusions in quartz grains. These processes are evidenced by quartz undulose extinction (Audétat and Günther, 1999) and from the abundant triple junctions of the contacts among quartz grains forming angles of ~120° ( Monecke et al. 2018), which is a common feature in quartz veins at Stypsi (Fig. 12b). 15 Fluid inclusions in quartz in the transitional and banded veins from Stypsi are rare and only three samples, out of six, contained workable inclusions. The maximum diameter of the studied inclusions reaches 20 μm, with the vast majority varying from 6 to 12 μm. The inclusions are elliptical, rounded, or irregular in shape. Most of ...
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... in the transitional and banded veins from Stypsi are rare and only three samples, out of six, contained workable inclusions. The maximum diameter of the studied inclusions reaches 20 μm, with the vast majority varying from 6 to 12 μm. The inclusions are elliptical, rounded, or irregular in shape. Most of the fluid inclu sions occur in clusters (Fig. 12b) and very rarely along secondary planes. Primary fluid inclusions distributed along growth zones are extremely rare and commonly too small to be measured. The fluid inclusions in these clusters have similar shapes and sizes and are considered 16 to be primary, using the criteria of Roedder (1984), Van den Kerkhof and Hein (2001), and ...
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... and are considered 16 to be primary, using the criteria of Roedder (1984), Van den Kerkhof and Hein (2001), and Goldstein and Reynolds (1994). The three samples of the transitional and banded veins, which do not contain workable fluid inclusions, are characterized by abundant (over 99%) vapor dominant inclusions without any recognizable liquid (Fig. 12c,d). No phase transitions were observed during microthermometric runs at low and high temperatures. Vapor dominated fluid inclusions occur in both the light and dark bands of quartz, however their proportion is higher in the dark bands since they contain numerous submicron-sized inclusions (Fig. 12c). Muntean and Einaudi (2000) have ...
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... inclusions without any recognizable liquid (Fig. 12c,d). No phase transitions were observed during microthermometric runs at low and high temperatures. Vapor dominated fluid inclusions occur in both the light and dark bands of quartz, however their proportion is higher in the dark bands since they contain numerous submicron-sized inclusions (Fig. 12c). Muntean and Einaudi (2000) have described similar fluid inclusion characteristics in the banded-type veins from the porphyry gold deposits of the Refugio district, northern ...
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... the basis of phase ratios observed at room temperature, combined with fluid-inclusion behavior during heating and freezing runs, four co-existing types of primary fluid inclusions were identified in the porphyry transitional-and banded-type veins. Type 1, two-phase aqueous inclusions are characterized by a vapor bubble occupying 10-20 vol% (Fig. 12e), and which homogenize into the liquid state upon heating. Type 2 inclusions contain three phases (Fig. 12f), a liquid, a vapor (occupying 10-15 vol% of the inclusions), and a colorless, isotropic cubic daughter mineral identified as halite. They homogenize into the liquid state by bubble disappearance (type 2a) or by dissolution of ...
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... heating and freezing runs, four co-existing types of primary fluid inclusions were identified in the porphyry transitional-and banded-type veins. Type 1, two-phase aqueous inclusions are characterized by a vapor bubble occupying 10-20 vol% (Fig. 12e), and which homogenize into the liquid state upon heating. Type 2 inclusions contain three phases (Fig. 12f), a liquid, a vapor (occupying 10-15 vol% of the inclusions), and a colorless, isotropic cubic daughter mineral identified as halite. They homogenize into the liquid state by bubble disappearance (type 2a) or by dissolution of halite after bubble disappearance (type 2b). Type 3 inclusions are two-phase and contain predominantly vapor ...
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... 10-15 vol% of the inclusions), and a colorless, isotropic cubic daughter mineral identified as halite. They homogenize into the liquid state by bubble disappearance (type 2a) or by dissolution of halite after bubble disappearance (type 2b). Type 3 inclusions are two-phase and contain predominantly vapor (~80-90 vol%) as well as a liquid phase (Fig. 12e,f). They homogenize to the vapor phase. They are the most common type of inclusions and have a maximum diameter of 20 µm. No freezing data could be obtained on Type 3 inclusions. Type 4 inclusions contain only a vapor phase (Fig. 12c,d), and no phase transitions were observed during microthermometric ...
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... (type 2b). Type 3 inclusions are two-phase and contain predominantly vapor (~80-90 vol%) as well as a liquid phase (Fig. 12e,f). They homogenize to the vapor phase. They are the most common type of inclusions and have a maximum diameter of 20 µm. No freezing data could be obtained on Type 3 inclusions. Type 4 inclusions contain only a vapor phase (Fig. 12c,d), and no phase transitions were observed during microthermometric ...
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... transparent quartz in the IS epithermal veins of the Stypsi prospect contains abundant large fluid inclusions up to 90 μm in length. Only two-phase aqueous inclusions (Type 1) with a vapor bubble occupying 20 to 30 vol% were identified (Fig. 12g). Many fluid inclusions of this type were affected by post-entrapment modifications, such as necking down or leakage (Fig. 12h,i). These inclusions commonly occur along healed micro-cracks, which formed due to mechanical intracrystalline strain (Audétat and Günther, 1999;Diamond and Tarantola, 2015). A variable liquid to vapor ratio ...
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... in the IS epithermal veins of the Stypsi prospect contains abundant large fluid inclusions up to 90 μm in length. Only two-phase aqueous inclusions (Type 1) with a vapor bubble occupying 20 to 30 vol% were identified (Fig. 12g). Many fluid inclusions of this type were affected by post-entrapment modifications, such as necking down or leakage (Fig. 12h,i). These inclusions commonly occur along healed micro-cracks, which formed due to mechanical intracrystalline strain (Audétat and Günther, 1999;Diamond and Tarantola, 2015). A variable liquid to vapor ratio characterizes these fluid inclusions and is probably attributed to a "stretching" process. Under these conditions, numerous ...
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... micro-cracks, which formed due to mechanical intracrystalline strain (Audétat and Günther, 1999;Diamond and Tarantola, 2015). A variable liquid to vapor ratio characterizes these fluid inclusions and is probably attributed to a "stretching" process. Under these conditions, numerous micro-fractures induce leakage of fluid inclusions after trapping (Fig. 12i), and sometimes they result in expanding of the vapor phase. In order to reduce the influence of post-entrapment changes on the inclusions of the epithermal veins, only inclusions with regular shapes and constant liquid to vapour ratios were selected for ...
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... results from 104 fluid inclusions in transitional and banded quartz veinlets at Stypsi porphyry system are summarized in Table 6. Saline, liquid-rich fluid inclusions (type 2) commonly coexist with vapor-rich inclusions (type 3) within the same cluster (Fig. 12f), and suggest heterogeneous entrapment during boiling (Roedder, 1984;Audétat et al., 2008). Inclusions trapped along the boiling curve do not require pressure corrections and the measured homogenization temperatures thus represent true fluid trapping temperatures ( Ramboz et al. 1982;Audétat et al. ...
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... veins dissolved at temperatures between 367 °C and 525 °C, which equates to salinities of 39.3-60.6 wt% NaCl equiv. Salinities in type 3 inclusions were not obtained due to their very small size, which made observation of the phases change impossible. Homogenization temperatures (Th) for type 1 inclusions in quartz range from 354 °C to >600 °C (Fig. 13a). The majority of type 2 halite-bearing liquid-rich fluid inclusions homogenized by disappearance of the halite crystal after the vapor bubble had disappeared (type 2b). Fluid inclusions that homogenize by halite disappearance are frequently reported in magmatic-hydrothermal ore systems (Baker and Lang, 2003;Bouzari and Clark, ...
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... Lang, 2003;Bouzari and Clark, 2006;Voudouris et al., 2008;Jiang et al., 2014). This behavior at Stypsi could be the result of post-entrapment modification during quartz deformation (Audétat and Günther, 1999;Becker et al., 2008;Shen et al., 2010), and for this reason only the inclusions homogenizing by vapor disappearance (type 2a) are shown in Fig. 13b. Post-entrapment modification is evidenced by quartz undulose extinction and local recrystallization, as suggested by Audétat and Günther (1999). In type 2 inclusions, the highest temperature observed for either the disappearance of the vapor bubble (Th = 391 °C −517 °C) or the dissolution of halite (Th = 405 °C-525 °C) was considered ...
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... °C) or the dissolution of halite (Th = 405 °C-525 °C) was considered as the final homogenization temperature. Homogenization temperatures of type 3 inclusions in transitional and banded veins range from 352 °C to 521 °C. Most values of Th for type 1, 2 and 3 fluid inclusions overlap between 430 °C and 520 °C and have a distinct maximum at ~490° C (Fig. ...
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... fluid inclusions of type 1 were obtained in quartz of the IS epithermal veins (Table 6). Eutectic temperatures (Te) are clustered around −21.2 °C, indicating that NaCl is the dominant salt in the fluid (e.g., Shepherd et al. 1985). Final ice melting temperatures range from −1.1 °C to −0.1 °C, corresponding to salinities of 0.2-1.9 wt% NaCl equiv (Fig. 13b). Homogenization temperatures (Th) vary between 231 °C and 288 °C, with a distinct maximum at ~ 270 °C (Fig. ...
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... are clustered around −21.2 °C, indicating that NaCl is the dominant salt in the fluid (e.g., Shepherd et al. 1985). Final ice melting temperatures range from −1.1 °C to −0.1 °C, corresponding to salinities of 0.2-1.9 wt% NaCl equiv (Fig. 13b). Homogenization temperatures (Th) vary between 231 °C and 288 °C, with a distinct maximum at ~ 270 °C (Fig. ...
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... on the limited number of samples derived from surface and analyzed in the present study, the contents for the different metals vary greatly: the porphyry-style ores at Stypsi have Cu/Mo ratios that range from 0.1 to 14, which overlap ratios from porphyry Cu-Mo, porphyry Mo, and porphyry Cu-Au deposits (according to the classification scheme of ; Fig. 14). The gold content is relatively high in some porphyry-style ores at Stypsi (e.g., 0.5 g/t in transitional and banded quartz veins) with an average grade of about 0.1 g/t. The Cu:Au ratios at Stypsi vary from 0.01 to 1.4, with the lowest ratio values resembling those of porphyry Au deposits, which are characterized by very low Cu grades ...
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... very low Cu:Au ratios (0.02 to 0.05) ( Baker et al., 2016). Several analyses of trace metals at Stypsi reveal elevated Re and Pd contents (up to 70 ppb), and a positive correlation between Re (and Mo) and Au, in accordance with the findings of for other Re-enriched deposits, as for example the Kışladağ porphyry Au-Mo deposit ( Baker et al., 2016) (Fig. 14, Table 4). A similar Au, Pd, and Re enrichment also occurs at Pagoni Rachi prospect, in northern Greece, thus suggesting similar magma generating and/or mineralizing processes at the local scale for both prospects. In addition, the Stypsi prospect is enriched in Ag, Te, Sn, Zn, and Pb, which may in part be due to the strong telescoping of the ...
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... banded veins at Stypsi suggest that the quartz and the substage I B ore mineralization (Au, magnetite, bornite, chalcopyrite and molybdenite) formed from a magmatic fluid under boiling conditions. The fluid in these veins consists of a saline brine (40-61 wt% NaCl equiv) that coexists with a lower salinity (6 to 14 wt% NaCl equiv) liquid phase ( Fig. 13b) and a low-density vapor-rich fluid, at temperatures of 430 °C-520 °C, with a thermal maximum at ~490 ...
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... inclusions data from IS epithermal veins imply a dilute (<2 wt% NaCl equiv) fluid with Th of 230 °C-290 °C (Fig. 12b). This fluid formed during the final stage of the magmatic-hydrothermal evolution of the system, and represents a mixture of moderately saline fluid with circulating meteoric water in the epithermal environment. Due to the absence of any evidence of boiling, we cannot yield an estimate of the formation pressures of these veins. However, ...
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... on surface geology, alteration mapping and ore mineralogy, the timing of the mineralizing processes in the area is summarized as follows and schematically illustrated in Fig. 15. Near-surface emplace ...
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... I B ) porphyry-style Cu-Mo-Au mineralization and associated calc-potassic and propylitic alteration within the stock and the surrounding lavas. Degassing of magmatic vapors during or after dike emplacement led to the formation of the high-temperature silicicand advanced argillic alteration zones in the volcanic rocks on top of the Stypsi system (Fig. 15a). Propylitic alteration overlaps the calc-potassic core during cooling and retrogression of the system, resulting in deposition of the substage I C ore assemblage within the transitional and banded quartz veins (Fig. 15b). The subsequent vein-type mineralization (D-type veins; Stage II) overprints, earlier veins and alteration, and was ...
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... of the high-temperature silicicand advanced argillic alteration zones in the volcanic rocks on top of the Stypsi system (Fig. 15a). Propylitic alteration overlaps the calc-potassic core during cooling and retrogression of the system, resulting in deposition of the substage I C ore assemblage within the transitional and banded quartz veins (Fig. 15b). The subsequent vein-type mineralization (D-type veins; Stage II) overprints, earlier veins and alteration, and was deposited under more acidic and cooler conditions (Fig. 15c). Waning of the hydrothermal activity was manifested by deposition of intermediate-sulfidation type base metal-rich assemblages that accompanied the formation of ...
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... core during cooling and retrogression of the system, resulting in deposition of the substage I C ore assemblage within the transitional and banded quartz veins (Fig. 15b). The subsequent vein-type mineralization (D-type veins; Stage II) overprints, earlier veins and alteration, and was deposited under more acidic and cooler conditions (Fig. 15c). Waning of the hydrothermal activity was manifested by deposition of intermediate-sulfidation type base metal-rich assemblages that accompanied the formation of Stage III quartz-carbonate veins and their shallow/distal (platy calcite-chalcedony epithermal veins) equivalents, as well as the high-sulfidation style chalcedony-barite veins ...
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... activity was manifested by deposition of intermediate-sulfidation type base metal-rich assemblages that accompanied the formation of Stage III quartz-carbonate veins and their shallow/distal (platy calcite-chalcedony epithermal veins) equivalents, as well as the high-sulfidation style chalcedony-barite veins on top of the Stypsi prospect (Fig. ...
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... et al., 2013). Lesvos island lies in the western extension of the NE-trending Edremit graben, in the southern part of Biga Peninsula, Turkey (Bonev and Beccaletto, 2007;Sanchez et al., 2016). Three major calderas (e.g., Stypsi, Mesotopos and Vatoussa) were described on Lesvos island by Piper (1992, 1993), Rokos Vamvoukakis et al. (2005) (Fig. ...
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... Stypsi prospect in the north-central part of the island is hosted by shoshonitic subvolcanic and volcanic rocks (Figs. 1-5) within a large caldera structure (Pe-Piper and Piper, 1993;Rokos et al., 2000). The geological formations of the study area include, in its lower parts, lavas of the Skoutaros Formation, overlain by lava flows of the Sykaminea Formation (Figs. 2a, 3a). The lavas of the Skoutaros Formation dominate the central part of the Stypsi ...
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... 9 km to the north of Stypsi, the Megala Therma Pb-Zn-Ag-AuTe epithermal deposit (Fig. 1) developed at the periphery of the Stypsi caldera ( Kontis et al., 1994;Voudouris and Alfieris, 2005). Host rocks for the mineralization at Megala Therma is a propylitically altered hornblende-biotite trachyandesite, which belongs to the Lower Lava Formation of Lesvos island ( Kontis et al., 1994). Mineralization is associated with ...
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... ore correlation diagrams reveal positive correlations between Au versus Ag, Au versus Mo, Mo versus Re and Mo versus Cu (Fig. 10). In the last two diagrams, samples that plot outside these trends, may reflect different mineralization stages and/or variable degrees of ...
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... inclusions or rims on pyrite (Fig. 9i), rarely molybdenite-pyrite veins crosscut sericitically altered rock, overprinted by argillic alteration (Fig. 7b). Molybdenite in Stages I and II contains up to 0.3 wt% and up to 1.96 wt% Re, respectively (Table 5). However, Re can vary by more than 1 wt%, within the same molybdenite crystal from Stage II (Fig. 11a-c), which is similar to the variable composition observed by Voudouris et al. (2009Voudouris et al. ( , 2013a) in molybdenite from other porphyry deposits in northern Greece. This heterogeneity is most likely due to the inhomogenous distribution of nano-sized particles of rheniite (ReS 2 ) throughout the crystal. Representative electron ...
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... observed by Voudouris et al. (2009Voudouris et al. ( , 2013a) in molybdenite from other porphyry deposits in northern Greece. This heterogeneity is most likely due to the inhomogenous distribution of nano-sized particles of rheniite (ReS 2 ) throughout the crystal. Representative electron microprobe compositions for molybdenite are plotted in Fig. 11d. Galena surrounds pyrite in substage I C and is associated with sphalerite, chalcopyrite, and molybdenite (Fig. 9h). Stage Ic galena contains up to 0.33 wt% Bi, 0.13 wt% Te, and 0.05 wt% Ag. Stages II and III galena is characterized by low concentrations of Ag, Bi, and ...
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... inclusions were studied in quartz from the porphyry transitional and banded quartz veins and the IS epithermal veins at Stypsi. The D-type and HS epithermal chalcedony veins did not contain fluid inclusions. At Stypsi, early quartz in the veins is characterized by anhedral grains (Fig. 12a). They are mainly equigranular and demonstrate a polygonal shape. These characteristics are common in early quartz veins in many porphyry copper systems and imply that the quartz has been extensively recrystallized ( Monecke et al., 2018). Subgrain rotation and grain boundary migration due to several pulses of fluid flow and the ...
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... recrystallization, which destroys most of the fluid inclusions in quartz grains. These processes are evidenced by quartz undulose extinction (Audétat and Günther, 1999) and from the abundant triple junctions of the contacts among quartz grains forming angles of ∼120° ( Monecke et al. 2018), which is a common feature in quartz veins at Stypsi (Fig. ...
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... in the transitional and banded veins from Stypsi are rare and only three samples, out of six, contained workable inclusions. The maximum diameter of the studied inclusions reaches 20 μm, with the vast majority varying from 6 to 12 μm. The inclusions are elliptical, rounded, or irregular in shape. Most of the fluid inclusions occur in clusters (Fig. 12b) and very rarely along secondary planes. Primary fluid inclusions distributed along growth zones are extremely rare and commonly too small to be measured. The fluid inclusions in these clusters have similar shapes and sizes and are considered to be primary, using the criteria of Roedder (1984), Van den Kerkhof and Hein (2001), and ...
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... three samples of the transitional and banded veins, which do not contain workable fluid inclusions, are characterized by abundant (over 99%) vapor dominant inclusions without any recognizable liquid (Fig. 12c,d). No phase transitions were observed during microthermometric runs at low and high temperatures. Vapor dominated fluid inclusions occur in both the light and dark bands of quartz, however their proportion is higher in the dark bands since they contain numerous submicron-sized inclusions (Fig. 12c). Muntean and Einaudi (2000) have ...
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... inclusions without any recognizable liquid (Fig. 12c,d). No phase transitions were observed during microthermometric runs at low and high temperatures. Vapor dominated fluid inclusions occur in both the light and dark bands of quartz, however their proportion is higher in the dark bands since they contain numerous submicron-sized inclusions (Fig. 12c). Muntean and Einaudi (2000) have described similar fluid inclusion characteristics in the banded-type veins from the porphyry gold deposits of the Refugio district, northern ...
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... the basis of phase ratios observed at room temperature, combined with fluid-inclusion behavior during heating and freezing runs, four co-existing types of primary fluid inclusions were identified in the porphyry transitional-and banded-type veins. Type 1, two-phase aqueous inclusions are characterized by a vapor bubble occupying 10-20 vol% (Fig. 12e), and which homogenize into the liquid state upon heating. Type 2 inclusions contain three phases (Fig. 12f), a liquid, a vapor (occupying 10-15 vol% of the inclusions), and a colorless, isotropic cubic daughter mineral identified as halite. They homogenize into the liquid state by bubble disappearance (type 2a) or by dissolution of ...
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... heating and freezing runs, four co-existing types of primary fluid inclusions were identified in the porphyry transitional-and banded-type veins. Type 1, two-phase aqueous inclusions are characterized by a vapor bubble occupying 10-20 vol% (Fig. 12e), and which homogenize into the liquid state upon heating. Type 2 inclusions contain three phases (Fig. 12f), a liquid, a vapor (occupying 10-15 vol% of the inclusions), and a colorless, isotropic cubic daughter mineral identified as halite. They homogenize into the liquid state by bubble disappearance (type 2a) or by dissolution of halite after bubble disappearance (type 2b). Type 3 inclusions are two-phase and contain predominantly vapor ...
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... 10-15 vol% of the inclusions), and a colorless, isotropic cubic daughter mineral identified as halite. They homogenize into the liquid state by bubble disappearance (type 2a) or by dissolution of halite after bubble disappearance (type 2b). Type 3 inclusions are two-phase and contain predominantly vapor (∼80-90 vol%) as well as a liquid phase (Fig. 12e,f). They homogenize to the vapor phase. They are the most common type of inclusions and have a maximum diameter of 20 µm. No freezing data could be obtained on Type 3 inclusions. Type 4 inclusions contain only a vapor phase (Fig. 12c,d), and no phase transitions were observed during microthermometric ...
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... (type 2b). Type 3 inclusions are two-phase and contain predominantly vapor (∼80-90 vol%) as well as a liquid phase (Fig. 12e,f). They homogenize to the vapor phase. They are the most common type of inclusions and have a maximum diameter of 20 µm. No freezing data could be obtained on Type 3 inclusions. Type 4 inclusions contain only a vapor phase (Fig. 12c,d), and no phase transitions were observed during microthermometric ...
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... style veins from Stypsi. Salinities were calculated based on equations of Bodnar (1993) Coarse-grained transparent quartz in the IS epithermal veins of the Stypsi prospect contains abundant large fluid inclusions up to 90 μm in length. Only two-phase aqueous inclusions (Type 1) with a vapor bubble occupying 20 to 30 vol% were identified (Fig. 12g). Many fluid inclusions of this type were affected by post-entrapment modifications, such as necking down or leakage (Fig. 12h,i). These inclusions commonly occur along healed micro-cracks, which formed due to mechanical intracrystalline strain (Audétat and Günther, 1999;Diamond and Tarantola, 2015). A variable liquid to vapor ratio ...
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... in the IS epithermal veins of the Stypsi prospect contains abundant large fluid inclusions up to 90 μm in length. Only two-phase aqueous inclusions (Type 1) with a vapor bubble occupying 20 to 30 vol% were identified (Fig. 12g). Many fluid inclusions of this type were affected by post-entrapment modifications, such as necking down or leakage (Fig. 12h,i). These inclusions commonly occur along healed micro-cracks, which formed due to mechanical intracrystalline strain (Audétat and Günther, 1999;Diamond and Tarantola, 2015). A variable liquid to vapor ratio characterizes these fluid inclusions and is probably attributed to a "stretching" process. Under these conditions, numerous ...
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... micro-cracks, which formed due to mechanical intracrystalline strain (Audétat and Günther, 1999;Diamond and Tarantola, 2015). A variable liquid to vapor ratio characterizes these fluid inclusions and is probably attributed to a "stretching" process. Under these conditions, numerous micro-fractures induce leakage of fluid inclusions after trapping (Fig. 12i), and sometimes they result in expanding of the vapor phase. In order to reduce the influence of postentrapment changes on the inclusions of the epithermal veins, only inclusions with regular shapes and constant liquid to vapour ratios were selected for ...
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... results from 104 fluid inclusions in transitional and banded quartz veinlets at Stypsi porphyry system are summarized in Table 6. Saline, liquid-rich fluid inclusions (type 2) commonly coexist with vapor-rich inclusions (type 3) within the same cluster (Fig. 12f), and suggest heterogeneous entrapment during boiling (Roedder, 1984;Bodnar, 2003;Audétat et al., 2008). Inclusions trapped along the boiling curve do not require pressure corrections and the measured homogenization temperatures thus represent true fluid trapping temperatures (Ramboz et al. 1982;Audétat et al. ...
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... temperatures (Th) for type 1 inclusions in quartz range from 354 °C to > 600 °C (Fig. 13a). The majority of type 2 halitebearing liquid-rich fluid inclusions homogenized by disappearance of the halite crystal after the vapor bubble had disappeared (type 2b). Fluid inclusions that homogenize by halite disappearance are frequently reported in magmatic-hydrothermal ore systems (Baker and Lang, 2003;Bouzari and Clark, ...
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... Lang, 2003;Bouzari and Clark, 2006;Voudouris et al., 2008;Jiang et al., 2014). This behavior at Stypsi could be the result of post-entrapment modification during quartz deformation (Audétat and Günther, 1999;Becker et al., 2008;Shen et al., 2010), and for this reason only the inclusions homogenizing by vapor disappearance (type 2a) are shown in Fig. 13b. Post-entrapment modification is evidenced by quartz undulose extinction and local recrystallization, as suggested by Audétat and Günther (1999). In type 2 inclusions, the highest temperature observed for either the disappearance of the vapor bubble (Th = 391 °C −517 °C) or the dissolution of halite (Th = 405 °C-525 °C) was considered ...
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... °C) or the dissolution of halite (Th = 405 °C-525 °C) was considered as the final homogenization temperature. Homogenization temperatures of type 3 inclusions in transitional and banded veins range from 352 °C to 521 °C. Most values of Th for type 1, 2 and 3 fluid inclusions overlap between 430 °C and 520 °C and have a distinct maximum at ∼490° C (Fig. ...
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... fluid inclusions of type 1 were obtained in quartz of the IS epithermal veins (Table 6). Eutectic temperatures (Te) are clustered around −21.2 °C, indicating that NaCl is the dominant salt in the fluid (e.g., Shepherd et al. 1985). Final ice melting temperatures range from −1.1 °C to −0.1 °C, corresponding to salinities of 0.2-1.9 wt% NaCl equiv (Fig. 13b). Homogenization temperatures (Th) vary between 231 °C and 288 °C, with a distinct maximum at ∼ 270 °C (Fig. ...
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... are clustered around −21.2 °C, indicating that NaCl is the dominant salt in the fluid (e.g., Shepherd et al. 1985). Final ice melting temperatures range from −1.1 °C to −0.1 °C, corresponding to salinities of 0.2-1.9 wt% NaCl equiv (Fig. 13b). Homogenization temperatures (Th) vary between 231 °C and 288 °C, with a distinct maximum at ∼ 270 °C (Fig. ...
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... of samples derived from surface and analyzed in the present study, the contents for the different metals vary greatly: the porphyry-style ores at Stypsi have Cu/Mo ratios that range from 0.1 to 14, which overlap ratios from porphyry Cu-Mo, porphyry Mo, and porphyry Cu-Au deposits (according to the classification scheme of Sinclair et al., 2009; Fig. 14). The gold content is relatively high in some porphyry-style ores at Stypsi (e.g., 0.5 g/t in transitional and banded quartz veins) with an average grade of about 0.1 g/t. The Cu:Au ratios at Stypsi vary from 0.01 to 1.4, with the lowest ratio values resembling those of porphyry Au deposits, which are characterized by very low Cu grades ...
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... to 0.05) ( Baker et al., 2016). Several analyses of trace metals at Stypsi reveal elevated Re and Pd contents (up to 70 ppb), and a positive correlation between Re (and Mo) and Au, in accordance with the findings of Sinclair et al. (2009) for other Re-enriched deposits, as for example the Kışladağ porphyry Au-Mo deposit ( Baker et al., 2016) (Fig. 14, Table 4). A similar Au, Pd, and Re enrichment also occurs at Pagoni Rachi prospect, in northern Greece, thus suggesting similar magma generating and/or mineralizing processes at the local scale for both prospects ( Voudouris et al., 2013a). In addition, the Stypsi prospect is enriched in Ag, Te, Sn, Zn, and Pb, which may in part be ...
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... molybdenite in D-type mineralization at Stypsi is significantly enriched in Re relative to molybdenite in the transitional and banded quartz veins. Such Re enrichment in late molybdenite was previously reported in other telescoped porphyry-epithermal systems such as Pagoni Rachi, Greece (Voudouris et al., 2013a) and Agua Rica, Argentina (Franchini et al., 2011), where a major episode of molybdenite formation (probably due to remobilization from B-type veins) took place during the D-veining event. ...
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... banded veins at Stypsi suggest that the quartz and the substage I B ore mineralization (Au, magnetite, bornite, chalcopyrite and molybdenite) formed from a magmatic fluid under boiling conditions. The fluid in these veins consists of a saline brine (40-61 wt% NaCl equiv) that coexists with a lower salinity (6 to 14 wt% NaCl equiv) liquid phase (Fig. 13b) and a low-density vapor-rich fluid, at temperatures of 430 °C-520 °C, with a thermal maximum at ∼490 ...
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... inclusions data from IS epithermal veins imply a dilute (< 2 wt% NaCl equiv) fluid with Th of 230 °C-290 °C (Fig. 12b). This fluid formed during the final stage of the magmatic-hydrothermal evolution of the system, and represents a mixture of moderately saline fluid with circulating meteoric water in the epithermal environment. Due to the absence of any evidence of boiling, we cannot yield an estimate of the formation pressures of these veins. However, ...
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... on surface geology, alteration mapping and ore mineralogy, the timing of the mineralizing processes in the area is summarized as follows and schematically illustrated in Fig. 15. Near-surface emplacement of microgranite porphyries within trachyandesites was succeeded by early Stage (I A and I B ) porphyry-style Cu-Mo-Au mineralization and associated calc-potassic and propylitic alteration within Fig. 15. Schematic diagram of the mineralizing processes in the Stypsi area: a) Near-surface emplacement of a ...
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... the timing of the mineralizing processes in the area is summarized as follows and schematically illustrated in Fig. 15. Near-surface emplacement of microgranite porphyries within trachyandesites was succeeded by early Stage (I A and I B ) porphyry-style Cu-Mo-Au mineralization and associated calc-potassic and propylitic alteration within Fig. 15. Schematic diagram of the mineralizing processes in the Stypsi area: a) Near-surface emplacement of a microgranite porphyry within trachyandesites of the Skoutaros Formation was succeeded by early substage (I A and I B ) porphyry-style Cu-Mo-Au mineralization and associated calc-potassic and propylitic alteration of the porphyry and ...
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... high-sulfidation epithermal-style chalcedony-barite veins overprint and/or occur above the Stypsi prospect. the stock and the surrounding lavas. Degassing of magmatic vapors during or after dike emplacement led to the formation of the hightemperature silicic-and advanced argillic alteration zones in the volcanic rocks on top of the Stypsi system (Fig. 15a). Propylitic alteration overlaps the calc-potassic core during cooling and retrogression of the system, resulting in deposition of the substage I C ore assemblage within the transitional and banded quartz veins (Fig. 15b). The subsequent vein-type mineralization (D-type veins; Stage II) overprints, earlier veins and alteration, and was ...
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... of the hightemperature silicic-and advanced argillic alteration zones in the volcanic rocks on top of the Stypsi system (Fig. 15a). Propylitic alteration overlaps the calc-potassic core during cooling and retrogression of the system, resulting in deposition of the substage I C ore assemblage within the transitional and banded quartz veins (Fig. 15b). The subsequent vein-type mineralization (D-type veins; Stage II) overprints, earlier veins and alteration, and was deposited under more acidic and cooler conditions (Fig. 15c). Waning of the hydrothermal activity was manifested by deposition of intermediate-sulfidation type base metal-rich assemblages that accompanied the formation of ...
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... core during cooling and retrogression of the system, resulting in deposition of the substage I C ore assemblage within the transitional and banded quartz veins (Fig. 15b). The subsequent vein-type mineralization (D-type veins; Stage II) overprints, earlier veins and alteration, and was deposited under more acidic and cooler conditions (Fig. 15c). Waning of the hydrothermal activity was manifested by deposition of intermediate-sulfidation type base metal-rich assemblages that accompanied the formation of Stage III quartz-carbonate veins and their shallow/distal (platy calcite-chalcedony epithermal veins) equivalents, as well as the high-sulfidation style chalcedony-barite veins ...
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... activity was manifested by deposition of intermediate-sulfidation type base metal-rich assemblages that accompanied the formation of Stage III quartz-carbonate veins and their shallow/distal (platy calcite-chalcedony epithermal veins) equivalents, as well as the high-sulfidation style chalcedony-barite veins on top of the Stypsi prospect (Fig. ...
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... Boiling and fluid mixing results in the enrichment of ore minerals in an Au-Ag bearing epithermal system (e.g. André-Mayer et al., 2002;Yılmaz et al., 2013;Voudouris et al., 2019;Melfos et al., 2019;Voudouris et al., 2022). ...
The Daghkesemen Au-bearing polymetallic vein-type deposit, which is the most important ore deposit of the Kazakh graben located in the northwestern part of the Lesser Caucasus, is hosted by calc-alkaline volcanic rocks (andesite, dacite, basaltic trachyandesite, trachyandesite, rhyodacite and their pyroclastics), subvolcanic rocks (andesite porphyry, dolerite, albitophyre/rhyodacite porphyry), and volcanic breccias. The mineralization is commonly observed as gold-bearing quartz-sphalerite-galena-chalcopyrite veins. The Daghkesemen Au-bearing polymetallic deposit, mostly observed in the propylitic alteration, is commonly composed of primarily sphalerite, galena, chalcopyrite, pyrite, native gold, bornite and magnetite, and secondarily digenite, cerussite, covellite, chalcocite, malachite, azurite, hematite, jarosite, and anglesite. The Daghkesemen Au-bearing polymetallic deposit mostly comprises Zn, Pb, Cu, Au, Ag, Fe and Cd. Homogenization temperatures (Th) of the fluid inclusions in sphalerite and quartz range from 200.1 °C and 281.2 °C and 266.4–266.7 °C, respectively. The low salinities for the fluid inclusions in sphalerite and quartz show a range of 0.7–6.6 wt. % NaCl equivalent and 2.7 to 3.1 wt. % NaCl equivalent, respectively. Eutectic temperatures measured in the fluid inclusions vary between −27.4 and −18.2 °C, indicating H2O–NaCl–KCl system. The δ³⁴SH2S values (−0.8 to −4.4‰) of sulfides (chalcopyrite, sphalerite, galena and pyrite) suggest a magmatic-hydrothermal origin for sulfur. The calculated sulfur isotopic geothermometer is value of 190 °C for sphalerite-chalcopyrite pair. The geochemical, mineralogical, sulfur isotopic and fluid inclusion data of the Daghkesemen Au-bearing polymetallic deposit suggest an intermediate sulfidation epithermal deposit associated with volcanic rocks.
... An evaluation of the mineral resources and critical assessment preceded according to the requirements of the ROBOMINERS technology. The contribution of AGG for the creation of the database includes approximately 172 records of mineral deposits located in Greece and was based on recently published literature and technical reports from the Hellenic Survey of Geology and Mineral Exploration, HSGME (formerly IGME) [6][7][8][9][10][11][12][13][14][15][16]. The required information, collected for each mineral deposit, which is important for the progress of the project and the development of the database, is briefly presented in Table 1. ...
ROBOMINERS is a new project funded under the European Union’s Research and Innovation Programme Horizon 2020, which aims at employing a bio-inspired robot, focused on the prospect of mineral exploration and extraction within Europe. ROBOMINERS’ innovative approach combines the creation of a new mining ecosystem through the development of a bioinspired robotic miner prototype, able to explore and mine mineral deposits which are currently considered uneconomic due to their small size and difficulty of access. The main objectives of the project include the creation of a European database of potentially suitable locations for the deployment of this novel technology. The building of the pan-EU mineral deposits database is considered vital for the development of the project as it will provide essential information related to deposit type and commodities, spatial and temporal distribution, and location of exploration targets. Several deposits have been reviewed and examined in Greece as potential targets suitable for the ROBOMINERS technology, after considering the specific restrictions and requirements of the project. The main targets have been determined and arranged according to the different aspects required by the applicability of the ROBOMINERS innovative technology.
... Recently, evidence for Ancient mining activities were also found in the island of Kea [16], while in Lemnos island, terra lemnia -lemnian earth -was exploited for its medicinal properties [17], as was the wellknown samian earth from Samos island [18]. In addition, alum, known in Greek as «styptyria lithos», was exploited in the village of Stypsi, Lesvos, where curiously, the porphyryepithermal systems [19] [20][21] [22] [23] are not known to have been exploited. The nearby ores at Megala Therma [24] were exploited only after the 19 th century. ...
The aim of this paper is to present the fluctuations of emery mining, from Ancient times to the present day, in the island of Naxos, Greece. Many Aegean islands were characterised in Antiquity by intense mining and quarrying activities, and many such activities continue even today. Emery is along with marble, the distinctive industrial mineral of the Cyclades, even now that production has largely ceased. This is an analysis of how emery came to be in Naxos, and how its existence and its exploitation by the local population shaped the society, the economy and the folklore of the local mining communities. In addition, since such mineral wealth is a matter not only of local but of national importance as well, the significance of emery export in Greek national economy will be discussed, along with how the changing international industrial and financial reality affected mining and thus the life of the locals. While presently profitable emery mining is rather unlikely, it is still possible for the insular community and economy to benefit from the establishment of a thematic geopark, based on the existing mines and the old mining infrastructure.
... W, Ce, Th, Nd and La are the most enriched rare metals at concentrations <75 ppm and are significantly correlated with each other (Supplement 3:Table S4-1). In Greece, M-type veins have been previously described from the Pagoni-Rachi, the Maronia, and the Stypsi porphyry deposits(Voudouris et al. 2013b, Voudouris et al. 2019b. The M-type veins at Vathi are different in terms of metallic content and alteration assemblages and are not associated with the introduction of any hypogene mineralization, as is the case at Pagoni-Rachi(Voudouris et al. 2013b, Voudouris et al. 2019b. ...
... In Greece, M-type veins have been previously described from the Pagoni-Rachi, the Maronia, and the Stypsi porphyry deposits(Voudouris et al. 2013b, Voudouris et al. 2019b. The M-type veins at Vathi are different in terms of metallic content and alteration assemblages and are not associated with the introduction of any hypogene mineralization, as is the case at Pagoni-Rachi(Voudouris et al. 2013b, Voudouris et al. 2019b. The potassic alteration that was overprinted by sericitic alteration is associated with A-type veins in the quartz monzonite and with disseminations in the latite at Vathi ( ...
Polymetallic Cu-Au-Bi-Pb-Ag-Te±Au-bearing quartz veins occur at Laodikino in the Serbo-Macedonian Massif in northern Greece. They are shear-related and hosted in metamorphic rocks, including two-mica gneisses and schists, biotite gneisses, and amphibolites. Barren aplites, pegmatites, and quartz veins are parallel or intrude along the main schistosity of the metamorphic rocks. Magmatic rocks are not exposed in the broader area. Ductile deformation episodes that affected the area include the pre-Alpine to Alpine D1 to D3 phases, and the post-Alpine D4 phase, which was followed by brittle deformation. The D3 deformation event is associated with Jurassic to Early Cretaceous amphibolite facies metamorphism, while the D4 deformation event is related to Late Cretaceous to Eocene retrograde greenschist facies metamorphism. Brittle deformation is mainly characterized by NW- and NE-trending normal to oblique faults. The D4 and the brittle deformation phase resulted in the Late Cretaceous to Miocene extensional collapse of the Serbo-Macedonian Massif and to the onset of the main Cenozoic magmatic and mineralizing event that affected the region during the Oligocene-Miocene. The polymetallic quartz veins are generally <1 m wide and crosscut D3 folds, and are sub parallel to or crosscut the D4 folds. Locally the metallic mineralization appears discontinuous and forms lenses. Exploration drilling during the early 1990s revealed that these veins reach a depth of 200 m and locally exceed 3 m in width. They exhibit typical hydrothermal characteristics including massive, comb and breccia textures (Fig. 1A-C). The main metallic assemblage includes pyrite, arsenopyrite, chalcopyrite, sphalerite, tetrahedrite, and galena, and minor amounts of pyrrhotite, magnetite, ilmenite, rutile, cobaltite, Bi-tellurides, electrum, and native bismuth (Fig. 1D-G). Restricted disseminations, aggregates, and pods of magnetite, pyrite, chalcopyrite, rutile, ilmenite, along with minor galena, arsenopyrite, xenotime, and bastnäsite occur in the host rocks (Fig. 1H,I). The alteration mineral assemblage includes quartz, sericite, chlorite, and minor calcite and barite. Hematite, goethite, malachite, chalcocite, covellite, cuprite, and native copper formed due to supergene oxidation. The polymetallic quartz veins are enriched in Ag (< 2433 ppm), Au (< 3 ppm), Co (< 166 ppm), Bi (< 83 ppm), Se (< 58 ppm), and In (< 53 ppm), while the disseminated assemblage is relatively more enriched in rare earth elements, including Ce (< 57 ppm), Nd (< 31 ppm), La (<30 ppm), Sm (< 7 ppm), and Dy (< 5 ppm), as well as in Ga (< 10 ppm). Tetrahedrite, chalcopyrite, and electrum are carriers of silver and gold. Bismuth and Te enrichment is mainly related to inclusions of pilsenite hosted in chalcopyrite. In the disseminated mineralization, Dy occurs in xenotime, while Ce and Nd are hosted mainly in bastnäsite. The Laodikino mineralization shares in common mineralogical, geochemical, and structural characteristics with other Cu-Au-Bi-Pb-Ag-Te-enriched intrusion-related deposits in northern Greece (e.g. Koronouda, Drakontio). These deposits constitute future exploration targets for rare and critical metals.
... The acquisition dwell time was set to 0.02 s for 74 Ge, 82 Se, 115 In, 125 Te, and 202 Hg, to 0.03 s for 107 Ag, to 0.04 s for 197 Au, and to 0.01 s for all other elements. The monitored isotopes include: 27 Al, 31 P, 34 S, 49 Ti, 51 V, 53 Cr, 55 Mn, 57 Fe, 59 Co, 60 Ni, 65 Cu, 66 209 Bi, 232 Th, and 238 U. The targeted areas in the polished sections were predefined to try and avoid mineral inclusions. ...
... Tungsten, Ce, Th, Nd, and La are the most enriched rare metals at concentrations <75 ppm and are significantly correlated with each other (Supplementary Table S4). In Greece, M-type veins have been previously described from the Pagoni-Rachi, the Maronia, and the Stypsi porphyry deposits [33,49,66]. The M-type veins at Vathi are different in terms of the contained metallic and alteration assemblages and are not associated with the introduction of any hypogene mineralization, as is the case at Pagoni-Rachi [33,49,66]. ...
... In Greece, M-type veins have been previously described from the Pagoni-Rachi, the Maronia, and the Stypsi porphyry deposits [33,49,66]. The M-type veins at Vathi are different in terms of the contained metallic and alteration assemblages and are not associated with the introduction of any hypogene mineralization, as is the case at Pagoni-Rachi [33,49,66]. ...
The Vathi porphyry Cu-Au±Mo deposit is located in the Kilkis ore district, northern Greece. Hydrothermally altered and mineralized samples of latite and quartz monzonite are enriched with numerous rare and critical metals. The present study focuses on the bulk geochemistry and the mineral chemistry of pyrite, chalcopyrite, magnetite, and titanite. Pyrite and chalcopyrite are the most abundant ore minerals at Vathi and are related to potassic, propylitic, and sericitic hydrothermal alterations (A- and D-veins), as well as to the late-stage epithermal overprint (E-veins). Magnetite and titanite are found mainly in M-type veins and as disseminations in the potassic-calcic alteration of quartz monzonite. Disseminated magnetite is also present in the potassic alteration in latite, which is overprinted by sericitic alteration. Scanning electron microscopy and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analyses of pyrite and chalcopyrite reveal the presence of pyrrhotite, galena, and Bi-telluride inclusions in pyrite and enrichments of Ag, Co, Sb, Se, and Ti. Chalcopyrite hosts bornite, sphalerite, galena, and Bi-sulfosalt inclusions and is enriched with Ag, In, and Ti. Inclusions of wittichenite, tetradymite, and cuprobismutite reflect enrichments of Te and Bi in the mineralizing fluids. Native gold is related to A- and D-type veins and is found as nano-inclusions in pyrite. Titanite inclusions characterize magnetite, whereas titanite is a major host of Ce, Gd, La, Nd, Sm, Th, and W.
... The Konos Hill porphyry-epithermal prospect comprises quartz porphyry stockworks, hosted in the intensively altered granodiorite porphyry, set in an NNW-trending direction (Figure 2), [49,61,62]. The veins are sinuous to planar and banded, a feature that was recently found to characterize quartz veins from several porphyry Cu-Mo-Re-Au systems in northeastern Greece [55,74]. The main metallic minerals are pyrite, molybdenite, rheniite, chalcopyrite along with minor bornite, enargite, colusite, and tetrahedrite/tennantite [48,55,60,[64][65][66][67], and are associated with sodic/potassic alteration of the host granodiorite. ...
The Konos Hill and Pagoni Rachi porphyry-epithermal prospects in northeastern Greece are characterized by abundant pyrite that displays important textural and geochemical variations between the various ore stages. It is commonly fine-grained and anhedral in the porphyry-related mineralization (M- and D-type veins), while it forms idiomorphic, medium- to coarse-grained crystals in the late, epithermal style veins (E-type). Porphyry-style pyrite from both prospects is characterized by an enrichment in Co, Se, Cu, and minor Zn, and a depletion in other trace elements, like Bi, Mo, Ag, etc. Pyrite in epithermal-style mineralization is mostly characterized by the presence of As, Bi, Pb, Ni, and Se. Gold in pyrite from all mineralization stages occurs as a non-stoichiometric substituting element, and its abundance correlates with As content. Arsenic in pyrite from Konos Hill records an increase from the porphyry stage to the epithermal stage (along with gold); however, at Pagoni Rachi, the highest Au and As contents are recorded in D-type pyrite and in the epithermal stage. The composition of the studied pyrite marks changes in the physico-chemical conditions of the ore-forming fluids and generally follows the geochemical trends from other porphyry-epithermal systems elsewhere. However, a notable enrichment of Se in the porphyry-style pyrite here is a prominent feature compared to other deposits and can be considered as an exploration tool towards Au-enriched mineralized areas.
... The Aegean Sea comprises numerous ore deposits and prospects, mostly of porphyry and epithermal nature (Melfos & Voudouris, 2017;Voudouris et al., 2018;Voudouris et al., 2019b). Curiously, many significant prospects were not discovered during the golden era of prospecting in the Aegean, like the Stypsi prospect (Periferakis, 2014Periferakis et al., 2017Periferakis et al., , 2018Voudouris et al., 2019c) in Lesvos, the Fakos prospect in Lemnos (Voudouris et al., 2018(Voudouris et al., , 2019d, and the Kondaros-Katsimouti mineralisation in Melos (Papavassiliou et al., 2016). In other instances of ore deposits, like in Megala Therma, Lesvos (Voudouris & Alfieris, 2005), exploitation was so brief that virtually no records or physical evidence exist. ...
The Keramos antimony mines in Chios Island are not amongst the most well known mining endeavours in the Islands of the Aegean, being overshadowed by more lasting and successful cases, such as those in Naxos and Serifos, to name but a few. Yet, their significance was great for the local society, whose prosperity followed the meteoric rise and fall of the mining enterprise, in two different and temporally distant periods. Antimony, despite its current status as a critical metal, and thus its value, could not, more than 50 years ago, be exploited in an economically viable way, in the studied historical and spatial context. The miners would suffer after the mines' closure, not just from relative poverty, but from the catastrophic health consequences of antimony mining. The mines and the associated mining facilities lay today almost forgotten and derelict. However, there is the possibility of their successful development into a thematic geopark, since they constitute a valuable geocheritage and cultural site.
... They are linked with magma emplacement along detachment faults and the exhumation of metamorphic core complexes in back-arc settings [8,9]. Characteristic examples occur in Thrace (Maronia, Pagoni Rachi, Konos, Kassiteres, Myli, Aisymi-Leptokarya, Melitena), Chalkidiki (Skouries, Fisoka, Dilofo, Tsikara), Kilkis (Doirani, Vathi, Gerakario), Limnos island (Sardes, Fakos) [9], and Lesvos island (Stypsi) [10]. ...
The Maronia Cu-Mo ± Re ± Au deposit is spatially related to a microgranite porphyry that intruded an Oligocene monzonite along the Mesozoic Circum-Rhodope belt in Thrace, NE Greece. The magmatic rocks and associated metallic mineralization show plastic and cataclastic features at the south-eastern margin of the deposit that implies emplacement at the ductile-brittle transition, adjacent to a shear zone at the footwall of the Maronia detachment fault. The conversion from ductile to brittle deformation caused a rapid upward magmatic fluid flow and increased the volume of water that interacted with the host rocks through high permeable zones, which produced extensive zones of potassic and sodic-calcic alteration. Potassic alteration is characterized by secondary biotite + K-feldspar (orthoclase) + magnetite + rutile + quartz ± apatite and commonly contains sulfides (pyrite, chalcopyrite, pyrrhotite). Sodic-calcic alteration consists of actinolite + sodic-calcic plagioclase (albite/oligoclase/andesine) + titanite + magnetite + chlorite + quartz ± calcite ± epidote-allanite. The high-oxidation state of the magmas and the hydrothermal fluid circulation were responsible for the metal and sulfur enrichments of the aqueous fluid phase, an increase in O2 gas content, the breakdown of the magmatic silicates and the production of the extensive potassic and sodic-calcic alterations. Brittle deformation also promoted the rapid upward fluid flow and caused interactions with the surrounding host rocks along the high temperature M-, EB-, A- and B-type veins.
... Coastal geomorphology is mainly controlled by the high erosion of the volcanic rocks that cover the majority of the island's coast. The geological formations of the coastal part of the study areas (Lesvos strait, Vatera, and Eresos, Figure 1b) consist of volcanic tuffs and lavas (i.e., Eresos Formation, the Miocene Polychnitos Ignimbrite, Mytilene volcanic formation), ophiolites, and metamorphic rocks (schists, phyllites, greywacke, and marbles; Voudouris et al. 2019). ...
This article presents the results of a marine geophysical and sedimentological study carried out around Lesvos Island (NE Aegean) to investigate the potential of exploitable marine aggregate (MA) deposits that could be used for beach replenishment purposes. Sub-bottom profiler data showed a good prospect for potential coarse-grained deposits in two of the three surveyed areas around Lesvos. Grain size and mineralogical analysis of the surficial sediments revealed sands that could properly feed nourishment schemes for eroded beaches or artificial beach development. Observed MA volumes are considered adequate for renourishment operations, when the threat of projected sea-level rise is introduced. Environmental constraints, as well as human activities, are considered for the suggestion and prioritization of specific areas for detailed surveying before future exploitation.
... The banded quartz veins constitute the early stage (Figures 7.3a, 7.3b, 7.3c, 7.5c) and the pyrite-molybdenite veins constitute the late stage of the mineralisation. The banded quartz veins are associated with Na-Ca alteration and propylitic alteration and the pyrite-molybdenite veins are associated with phyllic alteration (Voudouris et al., 2019). The microgranite porphyry is regarded as the core of the porphyry system and is affected by Na-Ca alteration. ...
... The colour of the veins is alternating between dark grey and black. Abundant vapour-rich fluid inclusions inside quartz crystals are responsible for the dark coloured bands (Voudouris et al., 2019). The quartz crystals of the veins appear granular anhedral or euhedral, under the microscope. ...
... Lower Lavas affected by propylitic alteration are slightly darker in colour than the fresh rocks. Both types of alterations are most probably synchronous (Voudouris et al., 2019). D-type veins are traditionally associated with phyllic/sericitic alteration (Figures 7.6c, 7.7d) in porphyry systems. ...
Lesvos Island comprises Lower Miocene, post-collisional volcanic to subvolcanic rocks with shoshonitic affinities overlying a metamorphic basement. The Stypsi porphyry-Cu-Mo-Au prospect is genetically related to a microgranite porphyry, which has intruded into trachyandesitic lavas of the Stypsi caldera. It comprises a stockwork of porphyry-style, black banded quartz- and quartz-actinolite veinlets associated with Na-Ca alteration, and a sericite-carbonate overprint related to IS epithermal quartz-carbonate veins. At higher topographic levels, a lithocap also hosts porphyry-style veinlets. Molybdenite, magnetite, pyrite, chalcopyrite, sphalerite, galena, bismuthinite and fahlores, are the metallic minerals of the porphyry mineralization. EPMA data indicate extremely high Re contents (up to 1.92 wt. %) in molybdenite, and low to moderate Fe contents (from 0.26 to 4.74 wt. %) in sphalerite. Fluid inclusion studies demonstrate coexistence of liquid- and vapor-rich inclusions in association with NaCl-bearing inclusions in the veinlets, suggesting that boiling occurred during the mineralization. Homogenization temperatures range between 344° and 510° C and salinities reach up to 44 % eq. NaCl. Bulk ore analyses revealed up to 843 ppm Cu, up to 76 ppm Mo, up to 0.5 ppm Au, up to 339 ppm Pb, up to 815 ppm Zn, up to 10 ppm Se, up to 4 ppm Te and Bi, and up to 23 ppm Sn. Quartz recrystallization from a silica gel is evidenced by botryoidal textures within banded quartz veinlets, a feature already described from porphyry-Au deposits. The late IS epithermal overprint, in the form of milky quartz-carbonate veins is controlled by NNE-trending faults, and extends further northwards to Megala Therma epithermal deposit, where fluorite in the veins and Au-Ag-Te enrichment occur.
