scholarly journals New perspective Reza gold deposit (Gedabek ore district, Lesser Caucasus, Azerbaijan)

2021 ◽  
Vol 30 (1) ◽  
pp. 53-64
Author(s):  
Nazim A. Imamverdiyev ◽  
Vasif M. Baba-zadeh ◽  
Samir S. Mursalov ◽  
Anar A. Valiyev ◽  
Mamoy I. Mansurov ◽  
...  
Keyword(s):  
Gold Deposit ◽  
Gold Mineralization ◽  
High Sulfidation ◽  
Gold Grade ◽  
Lesser Caucasus ◽  
New Perspective ◽  
Exploration Area ◽  
A Minor ◽  
Ore District ◽  
Gold Bearing

The article describes Reza gold deposit of Ugur exploration area located in Geda- bek Ore District of the Lesser Caucasus in NW of Azerbaijan. It is established that main mineralization in the Reza gold deposit consists of hematite-barite-quartz-kaoline veins- veinlets and breccia, pyrite stock-stockverk and quartz-sulfide veins. On the main orebody surface center secondary quartzites with vein-veinlets barite-hematite mineralization have occured over which remain accumulations of hydrous ferric oxides cementing breccias of quartz and secondary quartzites. “Reddish mass” is also observed in erosion parts, being an oxidation product of stock and stockverk limonite-hematite ores. Representing typical gossans, these accumulations by the data of trenches for thickness about 5-10 m contain gold 0.3-3.5 ppm and silver 1.0-45.0 ppm. There are three zones of gold mineralization within the Reza gold deposit: oxide mineralization; transition zone mineralization; sulfide mineralization. The oxide gold mineraliza- tion consists of clay-gravel weathering crust of kaolinite type. The gold-bearing mineralization has been oxidized to a depth of ap- proximately 50-100 meters. Typically, the gold mineralization is coarser and a minor increase in gold grade occurs within the oxides compared to the original rocks. The nugget effect increase in the gold grade of the oxides does not exceed approximately 10%. Deposit alteration signature has characteristics which suggest the current outcrop level may be near the top of a mineralized, gold-bearing high sulfidation epithermal (HSE) system. The gold mineralization at the deposit is interpreted as forming in shallow high sulfidation epith- ermal systems. The mineralization has been noted in well-confined hydrothermal breccia and associated with pyrite stock-stockwork. The majority of the deposit material and current estimates are formed within the barite-hematite-quartz-kaoline mineralization in the secondary quartzite rocks. The main brecciation and stockwork are hosted within secondary quartzite, sometime massive silicified andesite porphyritic rocks.

scholarly journals PROSPECTS OF NEWLY DISCOVERED UGUR AREA IN THE NORTHWEST OF THE GEDABEY ORE DISTRICT (LESSER CAUCASUS, AZERBAIJAN)

2021 ◽  
pp. 53-63
Author(s):  
N. Imamverdiyev ◽  
V. Baba-zadeh ◽  
S. Mursalov ◽  
A. Valiyev ◽  
M. Mansurov ◽  
...  
Keyword(s):  
Gold Mineralization ◽  
Gold Silver ◽  
Rock Chip ◽  
Hydrous Ferric Oxides ◽  
Lesser Caucasus ◽  
Exploration Area ◽  
Drill Holes ◽  
Positive Results ◽  
East West ◽  
Ore District

The article describes Ugur exploration area located in Gedabey Ore District of the Lesser Caucasus in NW of Azerbaijan. Results of trenches and channels sampling on the surface, RC bore holes and summary of significant drill intercepts (>0.29 ppm Au) of Ugur Exploration area are presented. It has been established that The deposit is enlarged by highly gold-silver result of surface outcrop rock chip samples over an area of 2.5 kms North-South by 2 kms East-West, with the Reza gold deposit located in the central part. Out of metallic minerals crystalline hematite was observed. On surface intensive barite and barite-hematite vein and veinlets, also gossan zones were observed. The main mineralization zones have been sampled in three trenches at a distance up to 270 m by trenches #1, #2 and #3 and received positive results for gold and silver. Also there have taken approximately 550 samples from outcrop #1 and #2. On the main orebody at surface centre there occured secondary quartzites with vein-veinlets barite-hematite mineralization over which there remain accumulations of hydrous ferric oxides cementing breccias of quartz and quartzites. And in erosion parts "reddish mass" being oxidation product of stock and stockverk hematite ores were observed. Representing typical gossans, these accumulations by the data of trenches for thickness about 5-10 m contain gold 0.3-2.0 ppm and silver 1.0-15.0 ppm. Ten diamond drill holes, named UGDD 01-10 were drilled in the center part of the deposit. The drill holes were sampled mainly in 1 meter lengths from the top of the hole to the bottom. The core samples were marked and placed into standard boxes. Significant intervals of weighted averages greater than 0.29 ppm over down hole intervals of 1 metres or greater (>0.29 ppm Au and >0.9 m) are summarized in table 3 below. In conclusion, the outcropping alteration at the deposit is typical of the upper steam-heated levels of high-sulfidation epithermal (HSE) deposits, which in most mineralized systems of this type, may cap higher-grade gold mineralization which is hosted by underlying vuggy and oxide zones.

scholarly journals Re–Os Pyrite Geochronological Evidence of Three Mineralization Styles within the Jinchang Gold Deposit, Yanji–Dongning Metallogenic Belt, Northeast China

Minerals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 448 ◽  
Author(s):  
Shun-Da Li ◽  
Zhi-Gao Wang ◽  
Ke-Yong Wang ◽  
Wen-Yan Cai ◽  
Da-Wei Peng ◽  
...  
Keyword(s):  
Gold Deposit ◽  
Northeast China ◽  
Gold Mineralization ◽  
Metallogenic Belt ◽  
Isotopic Analyses ◽  
Mantle Sources ◽  
Stage 1 ◽  
Geochronological Evidence ◽  
Gold Bearing

The Jinchang gold deposit is located in the eastern Yanji–Dongning Metallogenic Belt in Northeast China. The orebodies of the deposit are hosted within granite, diorite, and granodiorite, and are associated with gold-mineralized breccia pipes, disseminated gold in ores, and fault-controlled gold-bearing veins. Three paragenetic stages were identified: (1) early quartz–pyrite–arsenopyrite (stage 1); (2) quartz–pyrite–chalcopyrite (stage 2); and (3) late quartz–pyrite–galena–sphalerite (stage 3). Gold is hosted predominantly within pyrite. Pyrite separated from quartz–pyrite–arsenopyrite cement within the breccia-hosted ores (Py1) yield a Re–Os isochron age of 102.9 ± 2.7 Ma (MSWD = 0.17). Pyrite crystals from the quartz–pyrite–chalcopyrite veinlets (Py2) yield a Re–Os isochron age of 102.0 ± 3.4 Ma (MSWD = 0.2). Pyrite separated from quartz–pyrite–galena–sphalerite veins (Py3) yield a Re–Os isochron age of 100.9 ± 3.1 Ma (MSWD = 0.019). Re–Os isotopic analyses of the three types of auriferous pyrite suggest that gold mineralization in the Jinchang Deposit occurred at 105.6–97.8 Ma (includes uncertainty). The initial 187Os/188Os values of the pyrites range between 0.04 and 0.60, suggesting that Os in the pyrite crystals was derived from both crust and mantle sources.

U-Pb Dating on Hydrothermal Rutile and Monazite from the Badu Gold Deposit Supports an Early Cretaceous Age for Carlin-Type Gold Mineralization in the Youjiang Basin, Southwestern China

2021 ◽  
Author(s):  
Wei Gao ◽  
Ruizhong Hu ◽  
Albert H. Hofstra ◽  
Qiuli Li ◽  
Jingjing Zhu ◽  
...  
Keyword(s):  
Gold Deposit ◽  
Early Cretaceous ◽  
Gold Mineralization ◽  
Gold Deposits ◽  
Detrital Zircons ◽  
Youjiang Basin ◽  
Host Rocks ◽  
Gold Bearing ◽  
Carlin Type Gold Deposits

Abstract The Youjiang basin on the southwestern margin of the Yangtze block in southwestern China is the world’s second largest Carlin-type gold province after Nevada, USA. The lack of precise age determinations on gold deposits in this province has hindered understanding of their genesis and relation to the geodynamic setting. Although most Carlin-type gold deposits in the basin are hosted in calcareous sedimentary rocks, ~70% of the ore in the Badu Carlin-type gold deposit is hosted by altered and sulfidized dolerite. Although in most respects Badu is similar to other Carlin-type gold deposits in the province, alteration of the unusual dolerite host produced hydrothermal rutile and monazite that can be dated. Field observations show that gold mineralization is spatially associated with, but temporally later than, dolerite. In situ secondary ion mass spectrometry (SIMS) U-Pb dating on magmatic zircon from the least altered dolerite yielded a robust emplacement age of 212.2 ± 1.9 Ma (2σ, mean square of weighted deviates [MSWD] = 0.55), providing a maximum age constraint on gold mineralization. The U-Th/He ages of detrital zircons from hydrothermally mineralized sedimentary host rocks at Badu and four other Carlin-type gold deposits yielded consistent weighted mean ages of 146 to 130 Ma that record cooling from a temperature over 180° to 200°C and place a lower limit on the age of gold mineralization in the basin. Hydrothermal rutile and monazite that are coeval with gold mineralization have been identified in the mineralized dolerite. Rutile is closely associated with hydrothermal ankerite, sericite, and gold-bearing pyrite. It has high concentrations of W, Fe, V, Cr, and Nb, as well as growth zones that are variably enriched in W, Fe, Nb, and U. Monazite contains primary two-phase fluid inclusions and is intergrown with gold-bearing pyrite and hydrothermal minerals. In situ SIMS U-Pb dating of rutile yielded a Tera-Wasserburg lower intercept age of 141.7 ± 5.8 Ma (2σ, MSWD = 1.04) that is within error of the in situ SIMS Th-Pb age of 143.5 ± 1.4 Ma (2σ, MSWD = 1.5) on monazite. These ages are ~70 m.y. younger than magmatic zircons in the host dolerite and are similar to the aforementioned U-Th/He cooling ages on detrital zircons from hydrothermally mineralized sedimentary host rocks. We, therefore, conclude that the Badu Carlin-type gold deposit formed at ca. 144 Ma. The agreement of the rutile and monazite ages with the U-Th-He cooling ages of Badu and four other Carlin-type gold deposits in the Youjiang basin suggests that ca. 144 Ma is representative of a regional Early Cretaceous Carlin-type hydrothermal event formed during back-arc extension.

Micro-Nanoscale Characteristics of Pyrite and Its Implications for Gold Mineralization: Two Cases of Gold Deposits in the Youjiang Basin and Southwestern Tianshan Mountains

2021 ◽  
Vol 21 (1) ◽  
pp. 246-261
Author(s):  
Hongye Feng ◽  
Yiwen Ju ◽  
Bo Chen ◽  
Weixuan Fang ◽  
Hongjian Zhu ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gold Deposit ◽  
Gold Mineralization ◽  
Hydrothermal Solution ◽  
Economic Benefits ◽  
Gold Deposits ◽  
Formation Mechanisms ◽  
Mineralization Process ◽  
Nano Gold ◽  
Gold Bearing

The mineralogical and compositional characteristics of gold-bearing minerals and the occurrence of gold are not only of great significance to exploring the sources of ore-forming materials and their formation mechanisms but also helpful for designing reasonable beneficiations and smelting schemes and achieving remarkable economic benefits. This paper presents an integrated study on the crystal characteristics, elemental composition and distribution of pyrite (the main gold-bearing minerals), on the basis of electron probe microanalysis (EPMA), scanning electron microscopy (SEM), laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and nano-secondary ion mass spectrometry (NanoSIMS). The occurrence of gold in the Shuiyindong gold deposit and Ashawayi gold deposit has been studied by means of microscopy, SEM, and EPMA images, elemental correlations, S–Fe–As ternary diagrams, logAs–logAu diagrams and Au/As ratios. The gold in pyrite of the Shuiyindong deposit is in the form of nano gold inclusions and lattice gold. The gold in pyrite of the Ashawayi deposit dominantly exists in the form of nano gold inclusions or is present as micro-nano gold particles in the cracks or edges of pyrite, some of which can exist as lattice gold. The ore-forming hydrothermal solution of the Shuiyindong gold deposit is mainly underground hot brine, but it may be reformed by a deep magmatic hydrothermal solution or volcanic-subvolcanic hydrothermal solution. The ore-forming hydrothermal solution of the Ashawayi gold deposit is mainly derived from the metamorphic hydrothermal solution formed during the orogenic process, and the ore-forming process or post-mineralization process may be reformed by the leaching of underground hot brine. Finally, the characteristics of ore-forming fluids and evolution of the two types of deposits are determined via pyrite element surface scanning. This paper shows that micro-nanoscale study of gold-bearing pyrite is of great significance to understanding the gold mineralization process and is worth further study.

scholarly journals Carbonic fluids in the Hamadi gold deposit, Sudan: origin and contribution to gold mineralization

2017 ◽  
Vol 54 (5) ◽  
pp. 494-511 ◽  
Author(s):  
Xi-hui Cheng ◽  
Jiu-hua Xu ◽  
Jian-xiong Wang ◽  
Qing-po Xue ◽  
Hui Zhang
Keyword(s):  
Gold Deposit ◽  
Melting Temperature ◽  
Fluid Inclusions ◽  
Gold Mineralization ◽  
Narrow Range ◽  
Shear Zones ◽  
Quartz Veins ◽  
Wide Range ◽  
Homogenization Temperatures ◽  
Gold Bearing

The Hamadi gold deposit is located in North Sudan, and occurs in the Neoproterozoic metamorphic strata of the Arabian–Nubian Shield. Two types of gold mineralization can be discerned: gold-bearing quartz veins and altered rock ores near ductile shear zones. The gold-bearing quartz veins are composed of white to gray quartz associated with small amounts of pyrite and other polymetallic sulfide minerals. Wall-rock alterations include mainly beresitization, epidotization, chloritization, and carbonatization. CO2-rich inclusions are commonly seen in gold-bearing quartz veins and quartz veinlets from gold-bearing altered rocks; these include mainly one-phase carbonic (CO2 ± CH4 ± N2) inclusions and CO2–H2O inclusions with CO2/H2O volumetric ratios of 30% to ∼80%. Laser Raman analysis does not show the H2O peak in carbonic inclusions. In quartz veins, the melting temperature of solid CO2 (Tm,CO2) of carbonic inclusions has a narrow range of −59.6 to −56.8 °C. Carbonic inclusions also have CO2 partial homogenization temperatures (Th,CO2) of −28.3 to +23.7 °C, with most of the values clustering between +4.0 and +20 °C; all of these inclusions are homogenized into the liquid CO2 state. The densities range from 0.73 to 1.03 g/cm3. XCH4 of carbonic fluid inclusions ranges from 0.004 to 0.14, with most XCH4 around 0.05. In CO2–H2O fluid inclusions, Tm,CO2 values are recorded mostly at around −57.5 °C. The melting temperature of clathrate is 3.8–8.9 °C. It is suggested that the lowest trapping pressures of CO2 fluids would be 100 to ∼400 MPa, on the basis of the Th,CO2 of CO2-bearing one-phase (LCO2) inclusions and the total homogenization temperatures (Th,tot) of paragenetic CO2-bearing two-phase (LCO2–LH2O) inclusions. For altered rocks, the Tm,CO2 of the carbonic inclusions has a narrow range of −58.4 to ∼−57.0 °C, whereas the Th,CO2 varies widely (−19 to ∼+29 °C). Most carbonic inclusions and the carbonic phases in the CO2–H2O inclusions are homogenized to liquid CO2 phases, which correspond to densities of 0.70 to ∼1.00 g/cm3. Fluid inclusions in a single fluid inclusion assemblage (FIA) have narrow Tm,CO2 and Th,CO2 values, but they vary widely in different FIAs and non-FIAs, which indicates that there was a wide range of trapping pressure and temperature (P–T) conditions during the ore-forming process in late retrograde metamorphism after the metamorphism peak period. The carbonic inclusions in the Hamadi gold deposit are interpreted to have resulted from unmixing of an originally homogeneous aqueous–carbonic mixture during retrogress metamorphism caused by decreasing P–T conditions. CO2 contributed to gold mineralization by buffering the pH range and increasing the gold concentration in the fluids.

EOCENE MAGMA PLUMBING SYSTEM BENEATH CORTEZ HILLS CARLIN-TYPE GOLD DEPOSIT, NEVADA: IS THERE A DEEP-SEATED PLUTON?

2020 ◽  
Author(s):  
Celestine N. Mercer
Keyword(s):  
Gold Deposit ◽  
Melt Inclusions ◽  
Melt Inclusion ◽  
Gold Mineralization ◽  
Magma Reservoir ◽  
Plumbing System ◽  
Isotopic Tracers ◽  
Geophysical Surveys ◽  
Magmatic Fluids ◽  
Gold Bearing

Abstract The magmatic-hydrothermal conceptual model for Carlin-type gold deposit genesis calls upon deep-seated Eocene plutons as the primary source of gold-bearing fluids. However, geophysical surveys, geologic mapping, drilling, geochronology, isotopic tracers, and fluid inclusion chemistry have returned ambiguous evidence for the existence of such plutons. The high-grade Cortez Hills gold deposit in northern Nevada hosts shallow, Eocene syn- and postmineralization intrusions, offering an ideal site to investigate the existence of a deep-seated pluton beneath the district. Here, major and trace element analyses of quartz-hosted melt inclusions from four Eocene rhyolite dikes cropping out within the Cortez Hills pit and results from independent thermobarometers provide a window into the subsurface Eocene magmatic plumbing system to test the existence of a deep-seated source pluton. Dissolved volatile contents, melt inclusion entrapment pressures, and thermodynamic phase equilibria indicate that dike magmas were sourced from ~4- to ≥9-km depth from a polybaric magma reservoir residing as a physically and geochemically interconnected crystal mush with extractable or eruptible magma pockets. Magmas ascended adiabatically (nearly isothermally), exsolving fluids, evolving modestly by fractional crystallization, while trapping quartz-hosted melt inclusions steadily from depth to subvolcanic levels where they were emplaced. These data represent the first unequivocal evidence for a deep-seated magma reservoir from which fluid-saturated magma emanated and released magmatic fluids beneath the Cortez district during gold mineralization. However, further investigation into the specific metallogenic potential and metal budget of parental magmas and the partitioning of gold between silicate melt and aqueous fluids will be necessary to provide evidence that exsolved magmatic fluids may have been gold bearing.

scholarly journals Quartz Rb-Sr Isochron Ages of Two Type Orebodies from the Nibao Carlin-type Gold Deposit, Guizhou, China

Minerals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 399 ◽  
Author(s):  
Zheng ◽  
Yang ◽  
Gao ◽  
Chen ◽  
Liu ◽  
...  
Keyword(s):  
Low Temperature ◽  
Gold Deposit ◽  
Fluid Inclusions ◽  
Large Scale ◽  
Gold Mineralization ◽  
Gold Deposits ◽  
Quartz Veins ◽  
Golden Triangle ◽  
Mineralization Age ◽  
Gold Bearing

The Nibao gold deposit, which includes both fault-controlled and strata-bound gold orebodies, constitutes an important part of the Yunnan–Guizhou–Guangxi “Golden Triangle” region. Defining the mineralization age of these gold orebodies may provide additional evidence for constraining the formation ages of low-temperature orebodies and their metallogenic distribution in South China. Petrographic studies of gold-bearing pyrites and ore-related quartz veins indicate that these pyrites coexist with quartz or filled in vein-like quartz, which suggests a possible genetic relationship between the two from Nibao gold deposit. Minerals chemistry shows that Rb and Sr are usually hosted in fluid inclusions in quartz ranging from 0.0786 to 2.0760 ppm and 0.1703 to 2.1820 ppm, respectively. The Rb–Sr isotopic composition of gold-bearing quartz-hosted fluid inclusions from the Nibao gold deposit were found to have Rb–Sr isochron ages of 142 ± 3 and 141 ± 2 Ma for both fault-controlled and strata-bound orebodies, respectively, adding more evidence to previous studies and thus revealing a regional gold mineralization age of 148–134 Ma. These results also confirm the Middle-Late Yanshanian mineralizing events of Carlin-type gold deposits in Yunnan, Guizhou, and Guangxi Provinces of Southwest China. In addition, previous studies indicated that antimony deposits in the region which were formed at ca. 148–126 Ma have a close affinity with gold deposits. This illustrates that the regional low-temperature hydrothermal gold mineralization is related in space and time to the Yanshanian (ca. 146–115 Ma) magmatic activity. Specifically, the large-scale gold and antimony mineralization are considered to be inherently related to mantle-derived mafic and ultramafic magmatic rocks associated with an extensional tectonic environment. Based on the initial 87Sr/86Sr ratios of 0.70844 ± 0.00022 (2σ) and 0.70862 ± 0.00020 (2σ) for gold-bearing quartz veins from fault-controlled and strata-bound gold orebodies, respectively, at the Nibao gold deposit, as well as the C, H, O, and S isotopic characteristics of gold deposits located in the Golden Triangle region, we suggest that the mantle-derived material can be involved in the formation of the Nibao gold deposit and that the ore-forming fluid can be derived from a mixed crust–mantle source.

scholarly journals EPITHERMAL SYSTEMS AND GOLD MINERALIZATION IN WESTERN THRACE (NORTHERN GREECE)

2004 ◽  
Vol 36 (1) ◽  
pp. 416 ◽  
Author(s):  
C. Michael
Keyword(s):  
Gold Deposit ◽  
Structural Control ◽  
Gold Mineralization ◽  
Gold Deposits ◽  
Northern Greece ◽  
High Sulfidation ◽  
Epithermal System ◽  
Argillic Alteration ◽  
Low Sulfidation ◽  
Quartz Monzodiorites

Extensive epithermal systems occur within the Tertiary volcanosedimentary basins of western Thrace northern Greece. Gold deposits or perspective gold districts, related to the above epithermal systems have been recently found in the area. The gold mineralization is of the high – sulfidation type and is associated to a diversity in composition and style volcanic activity. Sappes epithermal system is the most important (Saint Demetrios and Viper deposits) and has developed in volcanic "ocks of intermediate composition accompanied by subvolcanic intrusives (dacite - andésites) and plutonio rocks (quartz - monzodiorites). Saint Demetrios and Viper gold deposits are flat lying and of high sulfidation type mineralizations hosted in hydrothermal breccia zones. Petrota epithermal system has developed in volcanoclastic and epiclastic rocks (Perama Hill gold deposit), in rhyolites (location Othontoto) and within hyaloclastites and crystal tuffs (location Mavrokoryfi). The mineralized epithermal zones have strong structural control. Perama gold deposit occurs at the intersection of NS and NW trending epithermal zones. These structures represent the higher grade "feeder" system. Pefka epithermal system is hosted in more acid volcanic vocks (dacites, rhyodacites) and at its southern part (Pasa lofos area) the system is associated with a more alkaline suit (shoshonitic rocks). The mineralized silicifid zones at Pefka mine would correspond to concentric fractures (sheeted fracturing) parallel to the margin of the breccia pipe. The gold mineralization occurs in veins. In general gold occurs in the form of native gold, gold tellurides or it is associated with enargite, luzonite, tetrahedhte. Advanced argillic alteration and intense silicification are very important for the epithermal systems in western Thrace. A unique low - sulfidation occurrence was found at the central and southern part of Sappes area. Adularla was found in veinlets overlapping argillic alteration zones of high - sulfidation system.

Gold and Porphyry Cu–Mo Mineralization of the Bumbat Ore Cluster and Its Relationship with the Early Paleozoic Magmatism of the Lake Zone (Western Mongolia)

2021 ◽  
Vol 62 (1) ◽  
pp. 121-133
Author(s):  
A.S. Borisenko ◽  
I.V. Gas’kov ◽  
V.V. Babich ◽  
A.A. Borovikov
Keyword(s):  
Gold Mineralization ◽  
Vein Quartz ◽  
Copper Ore ◽  
Quartz Veins ◽  
Porphyry Cu ◽  
Lake Zone ◽  
Geochemical Studies ◽  
Content Of Gold ◽  
Ore District ◽  
Gold Bearing

Abstract ––Geological, mineralogical, and geochemical studies of copper and gold mineralization in the Bumbat ore district of Mongolia have shown its association with igneous rocks of different ages formed under different geodynamic, geologic, and geochemical conditions. Copper ore occurrences (site 98 and Altan Gadas site) with an age of 518.0 ± 4.9 Ma have similar mineralogical and geochemical features and seem to be related to plagiogranite-porphyry stocks formed at the late island arc stage (524.5 Ma). The ores were deposited from weakly concentrated solutions with a low content of СО2 at 240–230 °С under subsurface conditions. The association of mineralization with plagiogranites, its localization predominantly in veins, and its essentially copper composition, with high contents of Zn, Mn, Ba, and, in some samples, Ag and Bi, permit us to assign this mineralization to the vein quartz–sulfide type. Its commercial value has yet to be assessed. Gold mineralization of the Three Hills and Darvi sites formed later (455.9 ± 4.3 Ma), during the formation of the final granitoid phases at the accretion–collision stage (511–465 Ma). These sites are mineralized crushing zones composed of hydrothermally altered rocks of sericite–quartz composition with veinlet and disseminated (stockwork) sulfide mineralization and gold-bearing quartz veins. The content of gold in the ores varies from tenths to tens of ppm, and its fineness varies from 700 to 1000‰. The ores of both sites have high contents of Cu, Zn, Mn, Ba, and, in places, Mo. Mineralization formed from hydrothermal solutions with TDS = 9.5–12.0 wt.% NaCl eq. at medium temperatures (230–300 °C) under subsurface conditions. The above specific features of gold mineralization are typical of the flank zones of porphyry Cu–(Mo) deposits.

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