Fluid Inclusion Characteristics of the Kıslada˘G Porphyry Au Deposit

minerals

Article Fluid Inclusion Characteristics of the Kı¸slada˘g Porphyry Au Deposit, Western Turkey

Nurullah Hanilçi 1,*, Gülcan Bozkaya 2, David A. Banks 3, Ömer Bozkaya 2 , Vsevolod Prokoﬁev 4 and Yücel Özta¸s 5

1 Department of Geological Engineering, Istanbul University-Cerrahpa¸sa,Avcılar, 34320 Istanbul, Turkey 2 Department of Geological Engineering, Pamukkale University, 20070 Denizli, Turkey; [email protected] (G.B.); [email protected] (Ö.B.) 3 School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK; [email protected] 4 Institute of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry, Russian Academy of Sciences, 119017 Moscow, Russia; [email protected] 5 TÜPRAG Metal Madencilik, Ovacık Mevki Gümü¸skolKöyü, Ulubey Merkez, 64902 U¸sak,Turkey; [email protected] * Correspondence: [email protected]; Tel.: +90-212-473-7070

Received: 17 November 2019; Accepted: 10 January 2020; Published: 13 January 2020

Abstract: The deposit occurs in a mid-Miocene monzonite magmatic complex represented by three different intrusions, namely Intrusion 1 (INT#1), Intrusion 2 (INT#2, INT #2A), and Intrusion 3 (INT#3). Gold mineralization is hosted in all intrusions, but INT#1 is the best mineralized body followed by INT#2. SEM-CL imaging has identified two different veins (V1 and V2) and four distinct generations of quartz formation in the different intrusions. These are: (i) CL-light gray, mosaic-equigranular quartz (Q1), (ii) CL-gray or CL-bright quartz (Q2) that dissolved and was overgrown on Q1, (iii) CL-dark and CL-gray growth zoned quartz (Q3), and (iv) CL-dark or CL-gray micro-fracture quartz fillings (Q4). Fluid inclusion studies show that the gold-hosted early phase Q1 quartz of V1 and V2 veins in INT#1 and INT#2 was precipitated at high temperatures (between 424 and 594 ◦C). The coexisting and similar ranges of Th values of vapor-rich (low salinity, from 1% to 7% NaCl equiv.) and halite-bearing (high salinity: >30% NaCl) fluid inclusions in Q1 indicates that the magmatic fluid had separated into vapor and high salinity liquid along the appropriate isotherm. Fluid inclusions in Q2 quartz in INT#1 and INT#2 were trapped at lower temperatures between 303 and 380 ◦C and had lower salinities between 3% and 20% NaCl equiv. The zoned Q3 quartz accompanied by pyrite in V2 veins of both INT#2 and INT#3 precipitated at temperatures between 310 and 373 ◦C with a salinity range from 5.4% to 10% NaCl eq. The latest generation of fracture filling Q4 quartz, cuts the earlier generations with fluid inclusion Th temperature range from 257 to 333 ◦C and salinity range from 3% to 12.5% NaCl equiv. The low salinity and low formation temperature of Q4 may be due to the mixing of meteoric water with the hydrothermal system, or late-stage epithermal overprinting. The separation of the magmatic fluid into vapor and aqueous saline pairs in the Q1 quartz of the V1 vein of the INT#1 and INT#2 and CO2-poor fluids indicates the shallow formation of the Kı¸slada˘g porphyry gold deposit.

Keywords: SEM-CL imaging; ﬂuid inclusion; porphyry Au deposit; Kı¸slada˘g;Turkey

1. Introduction Turkey is located on the western portion of the Tethyan Metallogenic Belt (TMB), which extends from Europe through Turkey to Pakistan, Tibet, China, and South Asia (e.g., [1,2]). The principal geological features and formation of the metallogenic belts of Turkey were controlled by the evolution

Minerals 2020, 10, 64; doi:10.3390/min10010064 www.mdpi.com/journal/minerals Minerals 2020, 10, 64 2 of 16 of the Neotethyan Ocean. Closure of the Neotethyan Ocean in eastern Turkey resulted in a Minerals 2020, 10, x FOR PEER REVIEW 2 of 16 continent–continent collision during the Miocene (e.g., [3,4]), while active continental subduction continuedin a continent in western–continent Turkey. collision An duringextensional the Miocene tectonic (e.g. regime, [3,4]), was while developed active continental in the latest Oligocene–earlysubduction continued Miocene (e.g., in western [5,6]), Turkey. late Miocene An extensional (e.g., [7– 9 tectonic]), or early regime Pliocene was developed onwards in(e.g., the [10]), that waslatest responsible Oligocene– forearly magmatism Miocene (e.g. and, [5,6 volcano-sedimentary]), late Miocene (e.g. basin, [7–9 development]), or early Pliocene in western onwards Anatolia (e.g.,(e.g. [11], and[10]), references that was responsibletherein). In for western magmatism Anatolia, and the volcano Eocene-sedimentary to Miocene basin magmatism development produced in numerouswestern porphyry Anatolia intrusion-related (e.g., [11] and reference hydrothermals therein). deposits In western [12] within Anatolia, three the main Eocene porphyry to Miocene belts: in the Biga,magmatism Tav¸sanlı,and produced Afyon-Konya numerous porphyry regions. The intrusion Kı¸slada˘gporphyry-related hydrothermal Au deposit, deposits the [12] subject within of this three main porphyry belts: in the Biga, Tavşanlı, and Afyon-Konya regions. The Kışladağ porphyry study, is located in the Afyon-Konya porphyry belt (Figure1). Au deposit, the subject of this study, is located in the Afyon-Konya porphyry belt (Figure 1).

FigureFigure 1. Simplified 1. Simplified regional regional geological geological map map of western of western Anatolia Anatoli (locationa (location shown shown in the in inset) the inset showing) showing Eocene to Miocene magmatic rocks and porphyry ore deposit belts (simplified from [12]). Eocene to Miocene magmatic rocks and porphyry ore deposit belts (simplified from [12]). The Kışladağ gold deposit is Europe’s largest producing mine with different stages of The Kı¸slada˘ggold deposit is Europe’s largest producing mine with different stages of mineralization mineralization occurring in the monzonite porphyry. The deposit consists of porphyry-style gold occurringmineralization in the monzonite connected porphyry.with a series The of overlapping deposit consists sub-volcanic of porphyry-style monzonite intrus goldions mineralization in one of connectedthe several with m aid series-to-late of Tertiary overlapping volcanic sub-volcaniccomplexes in western monzonite Turkey. intrusions Approximately in one 2.94 of million the several mid-to-lateounces Tertiary(Moz) of volcanicAu was produced complexes between in western 2006 and Turkey. 2018. ApproximatelyIt was reported that 2.94 the million deposit ounces had 8.8 (Moz) of AuMoz was Au produced (456 Mt of between ore with 2006 ca. 0.61 and g/t 2018. Au) Itof wasmeasured reported and thatindicated the deposit resources had at 8.8the Mozend of Au 2018, (456 Mt of orewith with an ca. inferred 0.61 g resource/t Au) of of measured 4.2 Moz Au and (290 indicated Mt ore with resources ca. 0.45 atg/t the Au, end using of 2018,0.35 g/t with Au cut an inferredoff) resource[13]. of The 4.2 geological Moz Au features (290 Mt of ore the with Kışladağ ca. 0.45 deposit g/t Au, were using studied 0.35 in gdetail/t Au by cut [14] off and)[13 classified]. The geological as a featuresgold of-only the porphyry Kı¸slada˘gdeposit deposit due were to studiedthe absence in detail of significant by [14] Cu and mineralization, classified as a i.e. gold-only, a low Cu/Au porphyry depositratio due of ~0.03. to the In absence this study of, significantthe objective Cu was mineralization, to investigate the i.e., characteristics a low Cu/Au of ratiofluid inclusions of ~0.03. in In this hydrothermal quartz from different stages in the three intrusions. Scanning electron microscopy- study, the objective was to investigate the characteristics of fluid inclusions in hydrothermal quartz cathodoluminescence (SEM-CL) imaging was used to establish the context of the fluid inclusion fromty dipesfferent that stages are present in the in three the different intrusions. vein Scanninggenerations electron. Therefore, microscopy-cathodoluminescence the formation history of the (SEM-CL)quartz imaging veins and was the used characteristics to establish of thethe contextfluid inclusions of the fluid they inclusionhost, related types to the that porphyry are present gold in the differentformation vein generations., are well constrained. Therefore, the formation history of the quartz veins and the characteristics of the fluid inclusions they host, related to the porphyry gold formation, are well constrained. 2. Geological and Lithological Features 2. Geological and Lithological Features The Kışladağ Au deposit is located approximately 55 km southwest of Uşak (Figure 1), in Thewestern Kı¸slada˘gAu Turkey, and deposit was the isfirst located porphyry approximately-type gold mineralization 55 km southwest discovered of in U¸sak(Figure Turkey. Due to1), in westernthe Turkey, extensional and tectonic was the regime first porphyry-type in western Anatolia, gold the mineralization early-to-late Tertiary discovered volcanic in Turkey. complexes Due to the extensional(Elmadağ, İteciktepe tectonic, regimeand Beydağı in western stratovolcanoes) Anatolia, outcrop the early-to-late close to Uşak Tertiary (Figure volcanic 2; [11]). complexes These (Elmada˘g, Iteciktepe,˙ and Beyda˘gıstratovolcanoes) outcrop close to U¸sak(Figure2;[ 11]). These Minerals 2020, 10, 64 3 of 16

stratovolcanoesMinerals 2020, 10 occur, x FOR in PEER a NE–SW REVIEW direction and have been dated between 17.29 Ma and 12.153 of 16 Ma by 40Ar/39Ar geochronology [15,16]. The Kı¸slada˘gporphyry Au deposit is related to monzonite intrusive and sub-volcanicstratovolcanoes rocks occur of in the a NE Beyda˘gıvolcanic–SW direction and complex have been with dated domes between and intrusive17.29 Ma and bodies 12.15 including Ma by 40Ar/39Ar geochronology [15,16]. The Kışladağ porphyry Au deposit is related to monzonite andesites, latites, trachytes, dacites, rhyodacites, and rare basalts intruded into the pre-Cretaceous intrusive and sub-volcanic rocks of the Beydağı volcanic complex with domes and intrusive bodies Menderes metamorphic rocks [11,14]. including andesites, latites, trachytes, dacites, rhyodacites, and rare basalts intruded into the pre- TheCretaceous main mineralizedMenderes metamorphic rocks of the rocks deposit [11,14]. are alkali intrusions [17]. These are all monzonites, on the basisThe of main their mineralized mineralogical rocks and of the chemical deposit compositions,are alkali intrusions and [17]. have The beense are subdivided all monzonites according, to crosscuttingon the basis relationshipsof their mineralogical [14], alteration, and chemical and compositions, mineralization. and have These been are subdivided (i) Intrusion according 1 (INT#1), (ii) Intrusionto crosscutting 2 (INT#2), relationships a more [14], intense alteration clay, and altered mineralization. equivalent These of Intrusion are (i) Intrusion 2 (INT#2A), 1 (INT#1), and (iii) Intrusion(ii) Intrusion 3 (INT#3). 2 (INT#2) All intrusions, a more are intense mineralized clay altered but equivalent the most economic of Intrusion gold 2 (INT#2A), mineralization and (iii) occurs withinIntrusion INT#1, INT#2,3 (INT#3). and All INT#2A intrusions (Figure are3 mineralized). These intrusions but the intruded most economic into a metamorphicgold mineralization basement (the Menderesoccurs within metamorphics) INT#1, INT#2, and and theINT#2A older (Figure Beyda˘gıvolcanics. 3). These intrusions intruded into a metamorphic basement (the Menderes metamorphics) and the older Beydağı volcanics.

FigureFigure 2. Geological 2. Geological map map of of the the U¸sakarea Uşak area [[11]11] and and location location of of the the Kışladağ Kı¸slada˘ggold gold deposit. deposit.

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FigureFigure 3. LithologicalLithological map map of of the the Kışladağ Kı¸slada˘gAu Au deposit deposit (modified (modiﬁed after [17]; [17]; Au grades from [14]). [14]).

2.1. Metamorphic Metamorphic Basement Basement The metamorphic basement,basement, representedrepresentedby by rocks rocks of of the the Menderes Menderes Massif, Massi isf, notis not exposed exposed inthe in topenhe open pitbut pit outcropsbut outcrop in thes in vicinity the vicinity of the deposit,of the deposit, and has and been ha intersecteds been intersected in the deep in drillthe deep holes. drill It is holescomposed. It is of composed biotite-rich of mafic biotite schists-rich to mafic quartz-bearing schists to schists quartz [14-bearing]. The schist schists is composed [14]. The mainly schist of is composedquartz, plagioclase mainly (albite), of quartz, and plagioclase white mica and(albite) contains, and quartz white veinsmica that and have contains been aquartzffected veins by intense that havedeformation. been affected In the by vicinity intense of thedeformation. open pit, the In foliationthe vicinity has aof low the dipopen angle pit, tothe the foliation south–east, has elsewherea low dip angleit is dominantly to the south flat-lying,–east, elsewhere but may it show is dominantly a rapid transition flat-lying, to abut steeply may dippingshow a rapid configuration transition [15 to]. a steeply dipping configuration [15]. 2.2. Intrusive Rocks

2.2.2.2.1. Intrusive Intrusion Rocks 1 (INT#1)

2.2.1.The Intrusion intrusive 1 (INT#1) rocks that host the Kı¸slada˘gAu deposit have been identified as INT#1, INT#2 (including INT#2 and INT#2A), and INT#3, in chronological order according to the relationship The intrusive rocks that host the Kışladağ Au deposit have been identified as INT#1, INT#2 observed both at the surface and in drill core data [14,17]. INT#1 is the oldest and best mineralized (including INT#2 and INT#2A), and INT#3, in chronological order according to the relationship intrusive phase in the Kı¸slada˘gmine area and forms the core of the system (Figure3). INT#1 comprises observed both at the surface and in drill core data [14,17]. INT#1 is the oldest and best mineralized abundant phenocrysts of K-feldspar (Figures4a and5a), plagioclase (30% of the rock by volume), intrusive phase in the Kışladağ mine area and forms the core of the system (Figure 3). INT#1 and biotite as the second most abundant phenocryst phase (up to 10% of the rock by volume). Blocky comprises abundant phenocrysts of K-feldspar (Figures 4a and 5a), plagioclase (30% of the rock by megacryst(s) of K-feldspar up to 1 cm are characteristic of this unit, but are not as common as quartz volume), and biotite as the second most abundant phenocryst phase (up to 10% of the rock by phenocrysts [14,17]. INT#1 has been classified in the monzonite field according to the primary mineral volume). Blocky megacryst(s) of K-feldspar up to 1 cm are characteristic of this unit, but are not as assemblages [14]. INT#1 is cross-cut by the younger porphyritic intrusions, and contacts between common as quartz phenocrysts [14,17]. INT#1 has been classified in the monzonite field according INT#1 and the surrounding volcanic rocks are generally obscured by alteration. However, contact with to the primary mineral assemblages [14]. INT#1 is cross-cut by the younger porphyritic intrusions, INT#3 is better preserved [14]. INT#1 contains on average of 0.86 g/t Au with a range between 0.38 and and contacts between INT#1 and the surrounding volcanic rocks are generally obscured by 1.65 g/t [14]. alteration. However, contact with INT#3 is better preserved [14]. INT#1 contains on average of 0.86 g/t2.2.2. Au Intrusion with a range 2 and between 2A (INT#2 0.38and and INT#2A) 1.65 g/t [14].

2.2.2.INT#2 Intrusion occurs 2 and in the2A center(INT#2 of and the pit,INT#2A) cutting the core of INT#1 (Figure3). The samples from INT#2 are ﬁne to medium grain-sized, comprising plagioclase phenocrysts (20–30% rock volume) up to 2 mm inINT#2 length, occurs in a in dominantly the center K-feldspar of the pit, groundmasscutting the core (Figures of INT#14b and (Figure5b). No 3). quartz The samples phenocrysts from INT#2were observed. are fine to The medium INT#2 zonegrain rocks-sized, have comprising a monzonite plagioclase composition phenocrysts and are (20 weakly–30% torock moderately volume) upmagnetic. to 2 mm The in INT#2A length intrusion, in a dominantly occurs in the K-feldspar southeast groundmass corner of the (openFigure pit,s 4b where and it 5b). cuts Nothe margin quartz phenocrysts were observed. The INT#2 zone rocks have a monzonite composition and are weakly to moderately magnetic. The INT#2A intrusion occurs in the southeast corner of the open pit, where it cuts the margin of INT#1 (Figure 3). INT#2A is a fine to medium-grained porphyritic rock, with

Minerals 2020, 10, x FOR PEER REVIEW 5 of 16 Minerals 2020, 10, 64 5 of 16 an intense pervasive clay–quartz alteration that appears to have selectively overprinted it (Figure of4c). INT#1 INT#2A (Figure contains3). INT#2A phenocrysts is a fine toof medium-grained plagioclase (~20%), porphyritic and possibly rock, with rare an quartz intense phenocrysts pervasive clay–quartz(Figure 5c). alteration Because of that the appears similarity to have in texture selectively between overprinted INT#2A it (Figureand INT#2,4c). INT#2A both have contains been phenocrystsconsidered to of be plagioclase the same (~20%), intrusion. and The possibly INT#2 rare contains quartz an phenocrysts average of (Figure 0.70 g/t5c). Au Because with a ofrange the similaritybetween 0.40 in texture and 0.96 between g/t Au, INT#2A whereas and the INT#2, INT#2A both has have a lower been average considered of 0.55 to be g/t the Au same with intrusion. a range Thebetween INT#2 0.37 contains and 0.83 an g/t average Au [14]. of 0.70 g/t Au with a range between 0.40 and 0.96 g/t Au, whereas the INT#2A has a lower average of 0.55 g/t Au with a range between 0.37 and 0.83 g/t Au [14]. 2.2.3. Intrusion 3 (INT#3) 2.2.3. Intrusion 3 (INT#3) INT#3 is the youngest intrusive body at the Kışladağ mine (Figure 3). It is located in the center of theINT#3 INT#1 is theand youngest its dyke intrusive-like structure body atis the elongated Kı¸slada˘gmine in an E (Figure–W direction.3). It is located INT#3 in is the a fine center-grained of the INT#1porphyritic and its rock dyke-like (Figure structures 4d and is 5d elongated), containing in an unaltered E–W direction. plagioclase INT#3 isphenocrysts a fine-grained (20– porphyritic30%), rare rockquart (Figuresz, and 4 biotited and 5 phenocrystsd), containing (both unaltered <5%), plagioclase and amphibole phenocrysts phenocrysts (20–30%), (5– rare10%). quartz, The and amphibole biotite phenocrysts (both have < been5%), and preferentially amphibole phenocrystsaltered to chlorite, (5–10%). but The their amphibole original phenocrysts prismatic have shape been is preferentiallypreserved [14,17 altered]. INT#3 to chlorite, contains but their very original fine-grained prismatic disseminated shape is preserved primary [14, 17magnetite]. INT#3 contains in the verygroundmass, fine-grained and is disseminated therefore magnetic. primary The magnetite bulk composition in the groundmass, of this intrusion and is lies therefore in the syenite magnetic. to Themonzonite bulk composition fields. The of contacts this intrusion of INT#3 lies with in the other syenite rocks to monzonite are generally fields. well The preserved, contacts of and INT#3 the withdecrease other in rocks gold are grade generally is abrup wellt across preserved, the boundary and the decrease with the in other gold intrusions grade is abrupt. The Au across grades the boundaryrange from with <5 to the 200 other ppb intrusions.[14]. The Au grades range from <5 to 200 ppb [14].

2.2.4. Latite P Porphyryorphyry and V Volcanoclasticolcanoclastic RocksRocks The undiundifferentiatedfferentiated latitelatite porphyry porphyry rocks rocks cover cover a largea large area area of of the the deposit, deposit, especially especially west west of the of mineralizedthe mineralized intrusions intrusions (Figure (Figure3). These 3). These rocks containrocks contain large feldspar large feldspar phenocrysts phenocrysts in a fine-grained in a fine- matrixgrained of matrix orthoclase of orthoclase and augite. and The augite. volcanoclastic The volcanoclastic rocks cover rocks the mineralized cover the mineralized intrusions and intrusions outcrop inand the outcrop east part in the of east the studypart of area the study (Figure area3). ( TheyFigure exhibit 3). The diy exhibitfferent different textures texture such ass fine-grainedsuch as fine- fragmentalgrained fragmental ash fall tu ashffs withfall tuffs pumice with fragments pumice (Figurefragments5e) to(Figure porphyritic 5e) to flowsporphyritic with flow flows banding with flow and brecciation.banding and In brecciat some drillion. holes,In some fine-grained drill holes plagioclase–hornblende, fine-grained plagioclase porphyries–hornblende with porphyries interlayered with ash fallinterlayered tuffs were ash intersected. fall tuffs Due were to the intersected weak propylitic. Due to alteration, the weak it is propylitic unclearwhether alteration, these it porphyries is unclear arewhether intrusive these bodies porphyries or flows. are Theintrusive contact bodies between or flows. the volcanoclastics The contact between and INT#1 the volcanoclastics is difficult to define and becauseINT#1 is ofdifficult the intensity to define of alteration, because of but the is intensity steeply inclined of alteration, and often but markedis steeply by inclined a tourmaline-rich and often hydrothermalmarked by a tourmaline breccia (Figures-rich hydrothermal3 and5f). breccia (Figures 3 and 5f).

Figure 4.4. Macroscopic view of didifferentfferent intrusive intrusive rocks. rocks. (a) IntrusiveIntrusive 1: 1: coarse coarse-grained-grained (~1 cm) euhedral K-feldsparsK-feldspars within the feldspar-richfeldspar-rich groundmass.groundmass. ( b) IntrusiveIntrusive 2:2: medium to fine-grainedfine-grained (1–2(1–2 mm) subhedral subhedral plagioclase, plagioclase, biotite, hornblende phenocrysts within the K-feldsparK-feldspar dominant dominant groundmass associated associated with with biotite biotite and tourmaline. and tourmaline (c) Intrusive. (c) 2A:Intrusive intensely 2A altered: intensely (kaolinization, altered sericitization)(kaolinization, feldspar sericitization) phenocrysts feldspar within phenocrysts the hydrothermal within the biotite-bearinghydrothermal clay-richbiotite-bearing (phyllosilicate) clay-rich altered(phyllosilicate groundmass.) altered (d ) groundmass Intrusive 3:. fine-grained(d) Intrusive ( < 31: mm)fine-grained unaltered (<1 feldspar mm) unaltered and partly-chloritized feldspar and amphibolepartly-chloritized phenocrysts amphibole within phenocrysts the feldspar within and quartz the feldspar groundmass and quartz (note that groundmass the width (note of the that photos the arewidth 16 cm).of the photos are 16 cm).

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Figure 5. Optical microscopic photomicrographs of of representative representative samples samples from from different different intrusions and volcanoclastic rocks. ( (aa)) Coarse Coarse-grained-grained (megacryst) (megacryst) K K-feldspar-feldspar phenocryst phenocryst within within a a silicifiedsilicified and hydrothermal biotite-bearingbiotite-bearing groundmass.groundmass. ( (bb)) Poly Poly-synthetic-synthetic zoned zoned plagioclase plagioclase and and biotite phenocrysts in in a silica-rich a silica-rich groundmass. groundmass (c) Intensively. (c) Intensively sericitized sericitized and kaolinitized and kaolinitized feldspar phenocrysts feldspar phenocrystsand groundmass and with groundmass opaque minerals. with opaque (d) Euhedral minerals. poly-synthetic(d) Euhedral twinned poly-synthetic plagioclase twinned and plagioclasepartly-chloritized and partly amphibole-chloritized phenocrysts amphibole within phenocryststhe silicified groundmass. within the silicified (e) Vitrophyric groundmass porphyritic. (e) Vitrophyricpyroclastic rockporphyritic containing pyroclastic silicified rock pumice containing and sericitized silicified biotitespumice withinand serici thetized devitrified biotites volcanic within thegroundmass. devitrified ( f volcanic) Radial tourmaline groundmass occurrences. (f) Radial and tourmaline fine-grained occurrences quartz associations and fine-grai inned the sample quartz associationsfrom the tourmaline in the sample breccia from zone. the tourmaline breccia zone.

2.3. Mineralization Mineralization and and Alteration Alteration Although the three intrusions are mineralized, the main gold mineralization in KışladağKı¸slada˘gis is related to the two earliest stages of sub sub-volcanic-volcanic intrusi intrusions,ons, INT#1 INT#1,, INT#2 INT#2,, and and INT# INT#2A2A ( (FigureFigure 66).). PorphyryPorphyry-style-style stockwork stockwork veins veins (Figure (Figure6a,b) 6a,b) in mineralized in mineralized intrusions intrusions include gold include grains gold associated grains associatedwith pyrites with that pyrites are less that than are 10 lessµm than in diameter 10 µm in [14 diameter]. These gold-hosted[14]. These gold stockworks-hosted arestockworks represented are representedby (i) banded by quartz–pyrite–tourmaline (i) banded quartz–pyrite– veinstourmaline (Figure veins6a) in (Figure INT#1, 6a) and in (ii) INT#1, tourmaline–quartz and (ii) tourmaline veins– in INT#2 (Figure6b, [ 14]). Stockwork veins are cut by sooty pyrite marcasite–tourmaline veins quartz veins in INT#2 (Figure 6b, [14]). Stockwork veins are cut ± by sooty pyrite ± marcasite– tourmaline(Figure6c) [ 14veins,17]. (Figure 6c) [14,17]. Generally, porphyry porphyry-type-type mineralization mineralization systems systems have have the the classic classic potassic, potassic, phyllic, phyllic, argillic argillic,, and propyliticand propylitic alteration alteration zones zones (e.g. (e.g.,, [18,19 [18]),,19 but]), but in inthe the Kışladağ Kı¸slada˘gdeposit, deposit, only only the the potassic potassic (Figure (Figure 77a),a), tourmalinetourmaline–white–white mica, advanced argillic argillic,, and argillic alteration (Figure(Figure7 7b)b) were were developed developed [ 14[14].]. The potassic alteration occurs in in INT#1, the the core core of the system, and it is characterized by the presence of fine ﬁne-grained,-grained, red red-brown-brown secondary biotite biotite and and K K-feldspar-feldspar altered altered from from a a pale pale pink buff buﬀ to nearly white color [14]. Euhedral (monoclinic-prismatic) adularia crystals (5 to 15 µm in size) are observed in some samples from INT#2 [20].

Minerals 2020, 10, 64 7 of 16 to nearly white color [14]. Euhedral (monoclinic-prismatic) adularia crystals (5 to 15 µm in size) are Minerals 2020, 10, x FOR PEER REVIEW 7 of 16 observedMinerals in 20 some20, 10, x samples FOR PEER fromREVIEW INT#2 [20]. 7 of 16 Tourmaline–whiteTourmaline–white mica mica alteration alterationoccurs occurs in and surrounds surrounds the the potassic potassic zone. zone. The Thetourmaline tourmaline Tourmaline–white mica alteration occurs in and surrounds the potassic zone. The tourmaline occursoccurs as envelopes as envelopes around around the the quartz quartz ± pyritepyrite veinlets veinlets (Figure (Figure 7c)7c) and and as as matrix matrix-supported-supported occurs as envelopes around the quartz ±± pyrite veinlets (Figure 7c) and as matrix-supported hydrothermalhydrothermal breccias breccias of theof the wall wall rocks rocks (Figure (Figure7 7d).d). hydrothermal breccias of the wall rocks (Figure 7d). AdvancedAdvanced argillic argillic alteration alteration is is represented represented byby quartz–alunitequartz–alunite ± dickitedickite ± pyrophyllitepyrophyllite ± pyritepyrite Advanced argillic alteration is represented by quartz–alunite ± ±dickite ± pyrophyllite± ± pyrite± mineralmineral assemblages assemblages [14 [14],], which which overprint overprint potassicpotassic and and tourmaline tourmaline–white–white mica mica zones zones indicating indicating a a mineral assemblages [14], which overprint potassic and tourmaline–white mica zones indicating a telescopingtelescoping of theof the alteration alteration zones. zones. However,However, the the X X-ray-ray diffraction diﬀraction studies studies of [20] of [did20] didnot find not any ﬁnd any telescoping of the alteration zones. However, the X-ray diffraction studies of [20] did not find any evidence of pyrophyllite and dickite in the samples studied here. evidenceevidence of pyrophyllite of pyrophyllite and and dickite dickite in in the the samples samples studied here. here. Argillic alteration occurs throughout the deposit and surrounding volcanic rocks. It is ArgillicArgillic alteration alteration occurs occurs throughout throughout the deposit the deposit and surrounding and surrounding volcanic volcanic rocks. rocks. It is dominated It is dominated by the development of kaolinite and smectite [14]. Tubular halloysite crystals were also by thedomi developmentnated by the of development kaolinite and of kaolinite smectite and [14 ].smectite Tubular [14]. halloysite Tubular halloysite crystals werecrystals also were observed also in observed in the volcanoclastic units [20]. The argillic alteration overprints the all other alteration observed in the volcanoclastic units [20]. The argillic alteration overprints the all other alteration the volcanoclasticassemblages. units [20]. The argillic alteration overprints the all other alteration assemblages. assemblages.

Figure 6. (a) Typical examples of mineralized stockwork veins with 1.12–0.607 g/t Au content in FigureFigure 6. ( a6.) Typical(a) Typical examples examples of of mineralized mineralized stockwork veins veins with with 1.12 1.12–0.607–0.607 g/t Au g/t contentAu content in in Intrusion (INT#1). (b) Tourmaline–quartz vein contains 0.27 g/t Au overprinting the K-feldspar IntrusionIntrusion (INT#1). (INT#1) (.b ()b Tourmaline–quartz) Tourmaline–quartz vein contains contains 0.27 0.27 g/t g / Aut Au overprinting overprinting the theK-feldspar K-feldspar alteration in Intrusion 2 (INT#2). (c) Example of the “sooty” pyrite veins with pyrite, marcasite, and alterationalteration in Intrusionin Intrusion 2 2 (INT#2). (INT#2). ( (cc) )E Examplexample of the of the“sooty” “sooty” pyrite pyrite veins with veins pyrite with, marcasite, pyrite, marcasite, and tourmaline envelopes in Intrusion 2A (INT#2A) [17]. and tourmalinetourmaline envelopes envelopes in inIntrusion Intrusion 2A 2A(INT#2A (INT#2A)) [17]. [17].

Figure 7. (a) Potassic alteration developed in INT#1. Early secondary biotite alteration is replaced by Figure 7. (a) Potassic alteration developed in INT#1. Early secondary biotite alteration is replaced by Figuresilica 7. –(pyritea) Potassic (Si–py) alteration flooding that developed is cut by later in INT#1. K-feldspar Early (K- secondarysp) veining [17] biotite. (b) alterationAdvanced argill is replacedic silica–pyrite (Si–py) flooding that is cut by later K-feldspar (K-sp) veining [17]. (b) Advanced argillic by silica–pyritealteration in (Si–py) INT#2A ﬂooding. (c) Quartz that-tourmaline is cut by vein later cuts K-feldspar the potas (K-sp)sic alteration veining in [17 INT#1]. (b and) Advanced (d) alteration in INT#2A. (c) Quartz-tourmaline vein cuts the potassic alteration in INT#1 and (d) argillictourmaline alteration–rich in matrix INT#2A.-supported (c) Quartz-tourmaline hydrothermal wall veinrock breccias cuts the. potassic alteration in INT#1 and tourmaline–rich matrix-supported hydrothermal wall rock breccias. (d) tourmaline–rich matrix-supported hydrothermal wall rock breccias.

Minerals 2020, 10, x FOR PEER REVIEW 8 of 16 Minerals 2020, 10, 64 8 of 16

3. Materials and Methods 3. MaterialsSamples and from Methods the Kışladağ porphyry Au deposit were collected from INT#1, INT#2, INT#2A, and INT#3Samples for from SEM the-CL Kı¸slada˘gporphyry and fluid inclusion Au studies. deposit Approximately were collected 100 from μm INT#1, thick double INT#2,-polished INT#2A, thinand INT#3section fors of SEM-CL quartz and were fluid prepared inclusion for studies. fluid inclusion Approximately and SEM 100-CLµm studie thick double-polisheds carried out at thin the LEMASsections laboratory of quartz were of Leeds prepared University, for fluid UK. inclusion The polished and SEM-CL wafers studieswere carbon carried-coated out at for the SEM LEMAS-CL observationlaboratory of using Leeds a University,n SEM-EDX UK. Oxford The polished Instruments wafers equipped were carbon-coated with a CL fordetector SEM-CL (University observation of Leedsusing, an Leeds SEM-EDX, UK). OxfordThe SEM Instruments-CL images equipped were obtained with a CLat an detector acceleration (University voltage of Leeds,from 15 Leeds, to 20 UK).kV, withThe SEM-CLa beam current images density were obtained of 15–20 at nA/mm. an acceleration voltage from 15 to 20 kV, with a beam current densityMicrothermometric of 15–20 nA/mm. measurements of fluid inclusions were carried out on 80–120 μm thick doublyMicrothermometric polished quartz measurements wafers according of fluid to inclusions standard were techniques carried [21,22 out on] 80–120 at the µ fluidm thick inclusion doubly laboratorypolished quartz in Istanbul wafers University according-Cerrahpaş to standarda, using techniques a Linkam [21,22 THMS] at the G fluid-600 heating inclusion–freezing laboratory stage. in TheIstanbul stage University-Cerrahpa¸sa,using was calibrated with pure a H Linkam2O, CO2 THMS, and G-600 H2O–NaCl heating–freezing fluid inclusion stage. standards, The stage andwas potassiumcalibrated withdichromate. pure H2 O,The CO accuracy2, and H was2O–NaCl determined fluid inclusion to be ±5 standards,°C at high andtemperatures potassium and dichromate. ±0.2 °C atThe temperatures accuracy was below determined zero. Duringto be 5 microthermometrC at high temperaturesy studies, and the0.2 valuesC at temperatures of homogeniz belowation ± ◦ ± ◦ temperaturezero. During (T microthermometryh), eutectic temperat studies,ure (Te), the last values ice melting of homogenization temperature temperature(Tm-ice), and (T dissolutionh), eutectic temperature of (Te), salt last crystals ice melting present temperature in the inclusion (Tm-ice), (Tm- andNaCl, dissolution Tm-KCl) were temperature measured. of salt crystals present in the inclusion (Tm-NaCl, Tm-KCl) were measured. 4. Results 4. Results 4.1. Scanning Electron Microscope-Catholuminescence (SEM-CL) Imaging 4.1. Scanning Electron Microscope-Catholuminescence (SEM-CL) Imaging The SEM-CL study was performed on polished quartz wafers (Figure 8a) from the three differentThe SEM-CL intrusions study (three was wafers performed from on INT#1, polished three quartz wafers wafers from (Figure INT#28a), fromand thefour three wafers di ff fromerent INT#3).intrusions In (three the studied wafers fromsamples, INT#1, two three veins wafers (V1 and from V2 INT#2, veins) and are four clearly wafers identified from INT#3). from In their the crosscuttstudied samples,ing relationship two veins in (V1INT#1 and and V2 veins)INT#2 are (Figure clearly 8). identified The stockwork from their veins crosscutting (V1 vein) that relationship include goldin INT#1 [14] in and both INT#2 INT#1 (Figure and INT#28). The (Figure stockwork 8a) are veins cut (V1by V2 vein) veins that in include INT#2 and gold INT#3 [ 14] in(Figure both INT#18b). and INT#2Detailed (Figure CL 8imagesa) are cut (Figure by V2 veins9a–d) in revealed INT#2 and multiple INT#3 (Figure generations8b). (Figure 9d) of quartz formationDetailed both CL in images V1 and (Figure V2 veins.9a–d) In revealed V1 veins, multiple these are generations: (i) CL-light (Figure gra9y,d) early of quartz formed formation mosaic- equigranularboth in V1 and quartz V2 veins. (Q1; InFigure V1 veins, 10a); these(ii) CL are:-gra (i)y or CL-light CL-bright gray, quartz early formed(Q2) that mosaic-equigranular dissolved and was subsequentlyquartz (Q1; Figure overgrown 10a); (ii) on CL-gray Q1, or or formed CL-bright dissolution quartz (Q2) cavities that dissolved in Q1 quartz and was(Figure subsequently 10b); (iii) concentricovergrown growth on Q1, or zoned formed quartz dissolution (Q3) alternating cavities in CL Q1-dark quartz and (Figure CL-gr 10ab);y bands (iii) concentric are particularly growth developedzoned quartz in (Q3) V2 veins alternating in INT#2 CL-dark and andINT#3 CL-gray (Figure bands 10b,c) are; and particularly (iv) CL- developeddark or CL in-gr V2ay veins micro in- fractureINT#2 and filling INT#3 late (Figure-stage quartz 10b,c); (Q4) and developed (iv) CL-dark both or CL-grayin V1 and micro-fracture V2 in all intrus fillingions ( late-stageFigure 10a,c). quartz In V2(Q4) vein, developed CL-gra bothy-to in dark V1 and gray V2 quartz in all (Q2)intrusions which (Figure developed 10a,c). by In dissolution V2 vein, CL-gray-to around the dark zoned gray quartz (Q2) which developed by dissolution around the zoned quartz (Q3), is accompanied by pyrite quartz (Q3), is accompanied by pyrite ± sphalerite (Figure 8b). This suggests that the dissolution of± quartzsphalerite (Q2) (Figure and sul8b).fides This developed suggeststhat from the the dissolution same fluids of quartzafter V1 (Q2) quartz and sulfidesdeposition. developed Similar from CL- texturesthe same have fluids been after reported V1 quartz in deposition.other porphyry Similar deposits CL-textures such as have No.2 been [23], reported Butte Montana in other porphyry[24], and Binghamdeposits suchCanyon as No.2 [25].[ 23], Butte Montana [24], and Bingham Canyon [25].

Figure 8. SEMSEM-CL-CL ima imagesges of quartz veins (V1 and V2) in INT#1 ( a)) and in INT#2 ( b).

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Figure 9. (a) Doubly polished thin section of INT#1 (sample KD-3a). (b) SEM-CL image of early FigureFigure 9. (a 9.) Doubly(a) Doubl polishedy polished thin thin section section of INT#1of INT#1 (sample (sample KD-3a). KD-3a) (b. )(b SEM-CL) SEM-CL image image of of early early quartz quartz vein cutting potassic alteration. (c) SEM-CL image clearly shows multiple generations of veinquartz cutting vein potassic cutting alteration. potassic alteration (c) SEM-CL. (c) image SEM-CL clearly image shows clearly multiple shows multi generationsple generation of quartzs of with quartz with CL-bright and CL-gray quartz. (d) At least three generations of quartz formation (1 to 3) CL-brightquartz andwith CL-gray CL-bright quartz. and CL (-dgr)a Aty quartz least three. (d) At generations least three generation of quartzs formation of quartz formation (1 to 3) are (1 to identiﬁed 3) are identified as CL- bright, CL-gray (dissolution qtz), and CL-dark, which is the last generation. as CL-are bright, identified CL-gray as CL- (dissolutionbright, CL-gra qtz),y (dissolution and CL-dark, qtz), and which CL-dark is the, which last generation. is the last generation.

Figure 10. Multiple generations of quartz formation identified by SEM-CL imaging in (a) INT#1, (b) Figure 10. Multiple generations of quartz formation identified by SEM-CL imaging in (a) INT#1, (b) FigureINT#2, 10. Multiple and (c) INT#3. generations (Q1) CL of-bright, quartz light formation grey early identiﬁed generation, by (Q2 SEM-CL and yellow imaging arrows) in (CLa) INT#1,-dark (b) INT#2, and (c) INT#3. (Q1) CL-bright, light grey early generation, (Q2 and yellow arrows) CL-dark INT#2,grey, and dissolution (c) INT#3. quartz, (Q1) CL-bright, (Q3) CL-dark light grey grey and early light generation, grey bands, (Q2concentric and yellow zoning arrows) quartz, andCL-dark grey, dissolution quartz, (Q3) CL-dark grey and light grey bands, concentric zoning quartz, and grey,(Q4) dissolution CL-grey quartz,to dark grey, (Q3) micro CL-dark-fracture grey filling and, light late-stage grey quartz. bands, concentric zoning quartz, and (Q4) (Q4) CL-grey to dark grey, micro-fracture filling, late-stage quartz. CL-grey to dark grey, micro-fracture ﬁlling, late-stage quartz.

Minerals 2020, 10, 64 10 of 16

Minerals 2020, 10, x FOR PEER REVIEW 10 of 16 4.2. FluidMinerals Inclusion 2020, 10, x StudiesFOR PEER REVIEW 10 of 16 Microthermometric studies were carried out on quartz veins in INT#1, INT#2, and INT#3. Fluid 4.2.4.2. FluidFluid InclusionInclusion StudiesStudies inclusions have been described as primary and secondary according to the criteria of [21,26]. The size Microthermometric studies were carried out on quartz veins in INT#1, INT#2, and INT#3. of the studiedMicrothermometric fluid inclusions studies varies were between carried 10 out and on 40 quartzµm, rarely veins inexceeding INT#1, INT#2 60 µm., and Four INT#3. different Fluid inclusions have been described as primary and secondary according to the criteria of [21,26]. typesFluid of fluid inclusions inclusion have assemblagesbeen described (FIAs; as primary Figure and 11 secondary) were identified according into the criteri studieda of samples[21,26]. on TheThe sizesize ofof thethe studiedstudied fluidfluid inclusionsinclusions variesvaries betweenbetween 1010 andand 4040 µm,µm, rarelyrarely exceedingexceeding 6060 µm.µm. FourFour the basis of phase assemblages observed at room temperature. These are: (i) aqueous liquid–vapor differentdifferent typestypes of of fluidfluid inclusion inclusion assemblages assemblages ( (FIAsFIAs;; FigureFigure 11)11) were were identified identified in in the the studied studied (LV-type) inclusions in which the liquid phase is dominant (Figure 12a); (ii) aqueous vapor–liquid samplessamples onon thethe basisbasis ofof phasephase assemblagesassemblages obserobservedved atat roomroom temperature.temperature. ThesThesee areare:: (i)(i) aqueousaqueous (VL-type)liquidliquid–– inclusionsvaporvapor (LV(LV--type)type) (Figure inclusionsinclusions 12b,c) inin in whichwhich which thethe the liquidliquid vapor phasephase phase isis dominantdominant is greater ((FigureFigure than 12a)12a) 70%;;; (ii)(ii) (iii)aqueousaqueous aqueous liquid–carbonicvaporvapor––liquidliquid fluid-vapor (VL(VL--type)type) inclusionsinclusions (LCV-type) ((FigureFigure inclusions 12b,c)12b,c) inin (Figure whichwhich thethe12d); vaporvapor and phasephase (iv) aqueous isis greatergreater liquid–vapor–solid thanthan 70%70%;; (iii)(iii) (LVS-type)aqueousaqueous inclusions liquidliquid––carboniccarbonic (Figure fluidfluid 12e,f),--vaporvapor which (LCV(LCV contain--type)type) solid inclusionsinclusions daughter ((FigureFigure phase(s). 12d)12d);; andand While (iv)(iv) theaqueousaqueous LV- and liquidliquid LVS-type–– inclusionsvaporvapor–– homogenizedsolidsolid (LVS(LVS--type)type) to inclusions liquid,inclusions the ((FigureFigure VL-type 12e,f)12e,f) homogenized,, whichwhich containcontain to a solidsolid vapor daughterdaughter phase, phase(s). orphase(s). decrepitated WhileWhile thethe prior to LV- and LVS-type inclusions homogenized to liquid, the VL-type homogenized to a vapor phase, or homogenization.LV- and LVS-type The daughterinclusions mineralshomogeniz (haliteed to liquid, and sylvite) the VL-type dissolved homoge beforenized vaporto a vapor disappearance phase, or in decrepitated prior to homogenization. The daughter minerals (halite and sylvite) dissolved before LVS-typedecrepitated inclusions. prior to homogenization. The daughter minerals (halite and sylvite) dissolved before vaporvapor disappearancedisappearance inin LVSLVS--typetype inclusions.inclusions.

Figure 11. Fluid inclusion assemblages (FIAs) identified at room temperature as (a) LV-type in FigureFigure 11. Fluid 11. Fluid inclusion inclusion assemblages assemblages (FIAs) (FIAs) identiﬁed identified at roomat room temperature temperature as as (a ) (a LV-type) LV-type in in INT#2, INT#2, (b) LVS-type in INT#1, and (c) VL-type in INT#2. (S: solid phase; L: homogenization into (b) LVS-typeINT#2, (b in) LVS INT#1,-type and in INT#1, (c) VL-type and (c) VLin- INT#2.type in INT#2. (S: solid (S: phase;solid phase; L: homogenization L: homogenization into into liquid liquid phase; V: homogenization into vapor phase). Numbers and letters are the temperature and phase;liquid V: homogenization phase; V: homogeni intozation vapor into phase). vapor phase). Numbers Numbers and letters and letters are the are temperaturethe temperature and and type of type of homogenization, Liquid or Vapor. homogenization,type of homogeni Liquidzation or, Vapor.Liquid or Vapor.

Figure 12. Fluid inclusion types distinguished according to the phases present at room temperature. Figure 12. Fluid inclusion types distinguished according to the phases present at room temperature. Figure(a) 12.LV-Fluidtype, (b inclusion,c) VL-type, types (d) LCV distinguished-type, and (e according,f) LVS-type to inclusions. the phases present at room temperature. (a) LV-type, (b,c) VL-type, (d) LCV-type, and (e,f) LVS-type inclusions. (a) LV-type, (b,c) VL-type, (d) LCV-type, and (e,f) LVS-type inclusions.

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Microthermometric measurements were carried out on fluid inclusions that were trapped during the formation of different generations of quartz (Q1, Q2, etc., see Figure 10) identified by SEM-CL imaging. The microthermometric data are summarized in Table1.

Table 1. Summary of microthermometric results from the diﬀerent veins and quartz types of Kı¸slada˘g Au deposit (Te: eutectic temperature; Tm: melting temperature; Clth: clathrate; L: liquid; V: vapor; n: number, n.d. = not determined).

Fluid Salinity Vein Quartz Te Tm-CO Tm-Clth T -CO Tm-Halite T Values T Intrusion Inclusion 2 Tm-Ice C h 2 NaCl h h Type Generation C C ◦ C C C C Mode Type, (n) ◦ ◦ ◦ ◦ ◦ wt % equiv. ◦ V1 Q1 LVS, (5) 70 to 17 - - - - 250 to 412 34 to 49 435 to 510 L − − V1 Q1 LV (7) 71 to 30 - 7 to 1 - - - 2 to 11 293 to 378 L − − − − V1 Q1 VL (3) n.d. - 5.3 to 1.8 - - - 1 to 7 424 to 520 V − − INT#1 V1 Q2 LV (3) n.d. - 8 to 1 - - - 3 to 11 336 to 346 L − − V1 Q2 LCV (4) 70 to 67 58.5 to 54 - - 21 - - 350 L − − − − V1 Q2–Q4 LVS 26 - - - - 112 to 261 28 to 35 250 to 351 L − V1 Q2–Q4 LV (14) 45 to 26 - 8.5 to 2 2.6 - - 3 to 12.5 257 to 333 L − − − − V1 Q1 LV (4) 68 to 43 - 11 to 14 - - - 15 to 18 371 to 443 L − − − − V1 Q1 VL (4) 68 to 38 ------480 to 594 V − − INT#2 V1 Q2 LV (10) 52 to 28 - 17 to 5 - - - 20 to 7.5 303 to 380 L − − − − V1 Q2 VL (2) 38 to 36 - 11 to 4 - - - 15 to 7 377 to 381 V − − − − V2 Q3 LV (3) 42 to 37 - 7 to 5 - - - 10 to 7 340 to 300 L − − − − V1 Q1 LVS (2) 93 to 40 - - - - 228 to 219 33 412 to 469 L − − V1 Q1 LV (8) 101 to 40 - 10.4 7.2 - 15 to 5 310 to 520 L INT#3 − − − V1 Q1 VL (2) 90.3 - - 7.8 - - 4.3 600 V − V2 Q3 LV (5) 26.4 - 4.8 to 3.3 - - - 7.6 to 5.4 373 to 310 L − − −

4.2.1. Intrusion#1 (INT#1) Fluid inclusion data were obtained from the V1 veins in Q1, Q2, and Q4 from INT#1 (Table1). LVS-, LV-, and VL-type inclusions were identified in Q1, while Q2 also includes LCV-type inclusions. LVS-type inclusions contain a halite daughter mineral that dissolved between 250 and 412 ◦C representing a salinity of 34 to 49 wt % NaCl equivalent. These inclusions homogenized between 435 and 510 ◦C into liquid by the disappearance of the vapor bubble. Some of the LVS inclusions in Q1 contain an opaque solid phase (Figure 11b) which optically looks to be hematite due to its slightly reddish color, and are common in the mineralizing fluids of porphyry deposits. The last ice melting (Tm-ice) temperature of the VL-type inclusions in Q1 was between 5.3 and 1.8 C representing 1% to 7% NaCl equivalent − − ◦ salinity. The VL-type inclusions homogenized to the vapor phase between 424 and 520 ◦C. The high salinity LVS and low salinity LCV-type inclusions with similar Th values indicate that these fluid inclusions represent separated phases of the primary magmatic fluid. The range in Th values and that some VL inclusions decrepitate prior to homogenization may indicate that some liquid was trapped when the vapor separated. The later trapped LV-type inclusions have eutectic and Tm-ice values between 71 and 30 C and 7 and 1 C, respectively (Table1). They have salinity and T between − − ◦ − − ◦ h 2 and 11 wt % NaCl equiv., and between 293 and 378 ◦C, respectively. The microthermometric data of the LV-type inclusions in Q2 of the V1 vein are similar to the LV-type inclusions of Q1 (Table1). The Tm-ice values range from 8 to 1 C corresponding to salinities − − ◦ between 3 and 11 wt % NaCl equivalent. These inclusions homogenized between 336 and 346 ◦C. The presence of CO2 was detected in inclusions from Q2 in the V1 vein. The melting temperature of solid CO was from 58.5 to 54 C indicating CO is the dominant gas, with at best only very minor 2 − − ◦ 2 other gaseous components being present. However, the clathrate and last ice melting temperature could not be determined due to the size of the inclusions. The LCV-type inclusions have Th values of 350 ◦C. Two LVS and fourteen LV-type inclusions could not be identified as belonging to either Q2 or Q4 (Table1). Two LVS-type inclusions include halite daughter minerals that dissolved at 112 and 261 ◦C representing 28% and 35% NaCl equiv. salinity. The Th values of these inclusions were between 250 and 351 ◦C. The LV-type inclusions in this group (Q2 or Q4) have Te and Tm-ice values ranging from 45 to 26 C, and from 8.5 to 2 C, respectively. In a few inclusions, there was no CO phase − − ◦ − − ◦ 2 detected at room temperature; however, the presence of clathrate was detected when heated to 2.6 ◦C Minerals 2020, 10, 64 12 of 16 Minerals 2020, 10, x FOR PEER REVIEW 12 of 16 when heated to 2.6 °C (Table 1). The salinity and Th values of these inclusions were between 3 and (Table1). The salinity and T h values of these inclusions were between 3 and 12.5 wt % NaCl equiv., 12.5 wt % NaCl equiv., and between 257 and 333 °C, respectively. and between 257 and 333 ◦C, respectively.

4.2.2. Intrusion#2 Intrusion#2 (INT#2) (INT#2) The LV-LV- andand VL-type VL-type fluid fluid inclusions inclusions were were detected detected in Q1,in Q1, Q2, Q2 and, and Q3 quartzQ3 quartz of V1 of and V1 V2 and veins V2 veinsin INT#2 in INT#2 (Table (1Table). LV- 1). and LV VL-type- and VL inclusions-type inclusions have similarhave similar Te values Te values ranging ranging from from68 to−68 to43 −43C, − − ◦ °C,and and68 to−68 38 to C,−38 respectively. °C, respectively. Tm-ice Tm values-ice valueswere between were between14 and −1411 andC in − LV-type11 °C in inclusions LV-type − − ◦ − − ◦ inclusionscorresponding corresponding to between to 16 between and 18 wt16 %and NaCl 18 wt equiv. % NaCl salinity, equiv while. salinity, Tm-ice while was Tm not-ice detected was not in VL-typedetected inclusions.in VL-type Althoughinclusions. the Although Th values the of Th LV-type values (fromof LV- 371type to (from 443 ◦ C)371 are to lower443 °C) than are thelower Th thanvalues the of T VL-typeh values (from of VL 480-type to 594(from◦C) 480 inclusions, to 594 °C) we inclusions, suggest the we two suggest inclusion the typestwo inclusion represent types fluid representseparation fluid pairs. separation The higher pairs Th .values The higher of some Th values VL inclusions of some may VL beinclusions artificially may high be dueartificially to trapping high dueof small to trapping amounts of of small liquid amounts with the of vapor. liquid with the vapor. The Q2 of V1V1 veinsveins containscontains LV-LV- and and VL-type VL-type inclusions inclusions (Table (Table1). 1). Both Both have have similar similar ranges ranges of Teof (fromTe (from52 − to52 to28 −28C °C for for LV LV and and38 −38 to to36 −36C °C for for VL-type), VL-type), salinity salinity (from (from 7% 7 to% 20%to 20% NaCl NaCl equiv. equiv. for − − ◦ − − ◦ forLV andLV and 7% 7 to% 15% to 15% NaCl NaCl equiv. equiv. for VL-type),for VL-type), and and Th (fromTh (from 303 303 to 380 to 380◦C for°C for LV LV and and 377 377 to 381 to 381◦C for°C VL-type).for VL-type). The V2 V2 vein vein in in INT#2 INT#2 includes includes sulfides sulfides (pyrite (pyritesphalerite) ± sphalerite) that cut that the cut V1 thevein. V1 This vein. vein This includes vein ± includesLV-type inclusions LV-type inclusions in Q3. The in Te Q3. and The Tm-ice Te and values Tm- ofice these values LV-type of these inclusions LV-type range inclusions from range42 to − from37 C,−42 and to from−37 °C,7 and to 5fromC, respectively−7 to −5 °C, (Tablerespectively1). The ( salinityTable 1). and The T salinityvalue ofand these Th inclusionsvalue of these was − ◦ − − ◦ h inclusionsbetween 7 was and 10betwee wt %n NaCl7 and equiv., 10 wt % and NaCl between equiv., 300 and and between 340 ◦C, 300 respectively. and 340 °C, respectively.

4.2.3. Intrusion#3 Intrusion#3 (INT#3) (INT#3) Microthermometric measurements measurements were were obtained obtained from from the the V1 and V2 veins of INT#3 which contain uneconomic goldgold mineralization.mineralization. While While LV-, LV- LVS-,, LVS and-, and VL-type VL-type inclusions inclusions are are identiﬁed identified in Q1, in Q1,the Q2the and Q2 Q3and contain Q3 contain only LV-typeonly LV inclusions-type inclusions (Table1 ).(Table The Te 1). values The Te of values the two of LVS-type the two inclusions LVS-type inclusionsin Q1 are in93 Q1 and are −4093 andC. The −40 solid°C. The phase solid was phase identiﬁed was identified as halite as due halite to itsdue rounded to its rounded cube edges. cube − − ◦ edges.The dissolution The dissolution temperature temperature was measured was measured at 228 and at 219 228◦C, and which 219 corresponds °C, which correspond to 33% NaCls salinity.to 33% NaClThese salinity. types of These inclusions types were of inclusions homogenized were by homogenized disappearance by of disappearance the vapor bubble of the between vapor 412bubble and between469 ◦C (Figure 412 and 13 ).469 °C (Figure 13).

Figure 13. The distribution of the homogenizationhomogenization temperatures (T h,, °◦C)C) of of the fluid fluid inclusions in differentdifferent generations of quartz from thethe didifferentfferent intrusions.intrusions.

The VL-type inclusions in Q1 have similar Te values to the LVS-type at 93 C, and have a very The VL-type inclusions in Q1 have similar Te values to the LVS-type at −−93 °C,◦ and have a very low salinitysalinity ofof 4.3%4.3% NaCl NaCl equiv. equiv. The The T hTvaluesh values of of this this type type of inclusionof inclusion were were measured measured at higher at higher than than600 ◦ C.600 In °C. this In instance, this instance the Th, valuesthe Th ofvalues VL-type of VL inclusions-type inclusions are much are higher much than higher LVS-type than inclusionsLVS-type inclusionsand therefore and it thereforeis less likely it is the less two li ﬂuidkely theinclusion two fluid types inclusion are linked. types However, are linked. more dataHowever, would more help datato conﬁrm would the help very to confirm high Th ofthe the very VL high inclusions. Th of the VL inclusions. The LV-type inclusions in Q1 have Te values between 101 and 40 C and a Tm-ice value at The LV-type inclusions in Q1 have Te values between −−101 and −−40 °C◦ and a Tm-ice value at 10.4 C. The formation of clathrate, and its dissolution temperature of 7.2 C in LV-type inclusions, −10.4 °C.◦ The formation of clathrate, and its dissolution temperature of 7.2 °C◦ in LV-type inclusions, indicates the existence of CO2 in the fluids. The Th and salinity values of LV-type inclusions range from 310 to 520 °C, and 5% to 15% NaCl equiv., respectively.

Minerals 2020, 10, 64 13 of 16

Minerals 2020, 10, x FOR PEER REVIEW 13 of 16 indicates the existence of CO2 in the fluids. The Th and salinity values of LV-type inclusions range fromThe 310 toV2 520 vein◦C, of andINT#3 5% contains to 15% NaCl Q3, which equiv., exhibits respectively. a growth zone texture. The Q3 includes LV- type The inclusions V2 vein ofthat INT#3 have contains Te and Q3, Tm which-ice valuesexhibits of a growth−26.4 °C,zone and texture. between The Q3−4 includes.8 and − LV-type3.3 °C, inclusions that have Te and Tm-ice values of 26.4 C, and between 4.8 and 3.3 C, respectively respectively (Table 1). The salinity and Th value− of these◦ inclusions range− from −5.4 to◦ 7.6 wt % NaCl (Tableequiv.,1 ).and The 310 salinity to 373 and °C, T respectively.h value of these The inclusions lower salinity range and from Th 5.4 value to 7.6 of wtfluids % NaCl in Q3 equiv., compared and 310 to tothe 373 fluids◦C, respectively.in Q1 is quite The distinct lower and salinity may andindicate Th value that ofthe fluids deposition in Q3 comparedof Q3 was tolinked the fluids with inmixing Q1 is quiteof a meteoric distinct fluid and may with indicate a magmatic that thefluid. deposition of Q3 was linked with mixing of a meteoric fluid with a magmatic fluid. 5. Discussion and Conclusions 5. Discussion and Conclusions Fluid Inclusion data provide valuable information in understanding the physico-chemical featureFluids of Inclusion fluids in data hydrothermal provide valuable systems, information and are in very understanding common in the stockwork physico-chemical quartz veins features of ofporphyry fluids in-type hydrothermal mineralization systems,. However, and are i veryt is well common established in stockwork that multiple quartz veins generations of porphyry-type of quartz mineralization.occur due to episodicHowever, fluid it is well flow established within individual that multiple hydrothermal generations of quartz quartz occur veins due in to porphyry, episodic fluidepithermal flow within deposits individual systems hydrothermal(e.g., [24,27–30 quartz]). Therefore, veins in it porphyry,is important epithermal to be able deposits to identify systems the (e.g.,quartz [24 generations,27–30]). Therefore, and relate it is the important characteristics to be able of the to identifyfluids they the quartz contain generations with mineralization. and relate theApplication characteristics of SEM of-CL the imaging fluids they improves contain the with ability mineralization. to constrain the Application timing of offluid SEM-CL inclusions imaging and improvesthe quartz thegenerations ability to in constrain veins compared the timing with of fluidmore inclusionstraditional andfluid the inclusion quartz generationspetrography in studies veins compared[24,29,31]. with more traditional fluid inclusion petrography studies [24,29,31]. The presence of gold mineralization in three didifferentfferent intrusions (INT#1 to #3) in the Kı¸slada˘gKışladağ gold depositdeposit cancan be be related related to to di ffdifferenterent phases phases of quartz of quartz veining. veining. Using Using SEM-CL SEM imaging-CL imaging clearly clearly shows theshows presence the presence of different of different quartz generations,quartz generations, Q1 to Q4, Q1 in to di Q4,fferent in different vein generations vein generations in the di ffinerent the intrusions.different intrusions. Fluid inclusion Fluid inclusion studies werestudies then we relatedre then torelated the di toff erentthe different vein (V1 vein and (V1 V2) and and V2) quartz and generationsquartz generations (Q1 to Q4)(Q1 that to Q4) occur. that Even occur though. Even there though is no there quantitative is no quantitative microanalysis microanalysis of fluids inof Q1,fluids due in to Q1, the due presence to the of presence opaque mineralsof opaque in minerals LVS inclusions, in LVS the inclusions, CL-bright, the light CL gray-bright, luminescence light gray quartzluminesc (Q1)ence in V1quartz vein (Q1) should in be V1 the vein earliest should formed be the gold-hosted earliest formed quartz. gold Fluid-hosted inclusion quartz. data showFluid thatinclusion the Q1 data of V1show vein that in the INT#1 Q1 isof relatedV1 vein with in INT#1 immiscible is related fluids with shown immiscible by the fluids co-existence shown ofby LVS, the which have T between 435 and 510 C, with >40% NaCl salinity, and VL-type inclusions with T co-existence ofh LVS, which have Th between◦ 435 and 510 °C, with >40% NaCl salinity, and VL-typeh between 424 and 520 C, with 1% to 7% NaCl equiv. salinity (Table1; Figure 14). Coexisting liquid-rich inclusions with Th between◦ 424 and 520 °C, with 1% to 7% NaCl equiv. salinity (Table 1; Figure 14). highlyCoexisting saline liquid and vapor-rich-rich highly low saline saline and inclusions vapor- inrich most low hydrothermal saline inclusions deposits in indicate most hydrothermal the different phasesdeposits were indicate generated the different by immiscibility phases were (e.g., generated [21,32]). by immiscibility (e.g., [21,32]).

Figure 14.14. HomogenizationHomogenization temperature temperature versus versus salinity salinity of worldof world porphyry porphyry copper copper deposits deposits (from (from [33]) compared[33]) compared with Kı¸slada˘gdata.with Kışladağ data.

The quartz of the V1 vein in INT#2 also contains LV- and VL-type inclusions, indicating fluid immiscibility, which have a Th range of 371–443 °C and 480–594 °C , respectively. The existence of immiscibility during the formation of gold-bearing Q1 in the V1 veins of both INT#1 and INT#2 indicates the Th values are equal to the trapping temperature. The Th and salinity values of the Q2 in

Minerals 2020, 10, 64 14 of 16

The quartz of the V1 vein in INT#2 also contains LV- and VL-type inclusions, indicating fluid immiscibility, which have a Th range of 371–443 ◦C and 480–594 ◦C, respectively. The existence of immiscibility during the formation of gold-bearing Q1 in the V1 veins of both INT#1 and INT#2 indicates the Th values are equal to the trapping temperature. The Th and salinity values of the Q2 in V1 veins of both INT#1 and INT#2 have similar ranges (Th between 336 and 380 ◦C) and are lower than the Q1 Th values. The low CO2 content of the Q1 and Q2 can be used to infer a shallow depth of trapping. CO2-rich fluids in porphyry systems are generally indicative of depths of 1–5 km and the shallow depth (<1 km) has been suggested (e.g., [14,23,34,35]) as an important factor in the gold-rich nature of Kı¸slada˘gdeposit. The late-stage fluid, represented by Q3 associated with sulfides in V2 veins both of INT#2 and INT#3, has lower salinities (from 5% to 10% NaCl equiv.) and Th (from 300 to 373 ◦C) than the earlier gold-bearing Q1 (Figure 14). Finally, LV-type inclusions in Q4, which is the micro-fracture filling and represents late-stage fluids, have lower Th (from 257 to 333 ◦C) and salinities (from 3% to 12.5% NaCl equiv.) Both Th and salinity are lower than other quartz generations and may indicate dilution of magmatic fluids by meteoric water. However, the overprinting of the porphyry mineralizing stage by a late-stage epithermal system is also possible. Telescoping in porphyry-epithermal systems is known and [14] has suggested this has occurred at the Kı¸slada˘goccurrences. Therefore, we suggest that the vein and quartz associations and the temperatures and salinities we have measured are best explained as supporting the process of a late-stage epithermal overprint of the porphyry mineralization. The general scenario is one of the repeated pulses of fluids typical for a porphyry system followed by a change to the lower temperatures of epithermal systems. However, as the pulses of fluids progress with time, the amount of gold mineralization decreased from INT#1 to INT#3, and this suggests that the source reservoir was being depleted in some critical metals.

Author Contributions: Investigation, N.H. and G.B., formal analysis, N.H. and V.P., writing—original draft preparation, N.H., Ö.B., and D.A.B.; resources, N.H., G.B., D.B., Ö.B., and Y.Ö. All authors have read and agreed to the published version of the manuscript. Funding: This research received no external funding. Acknowledgments: The authors would like to thank the TÜPRAG mining company for their permission to investigate the mining site. Conﬂicts of Interest: The authors declare no conﬂicts of interest.

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