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4 pages, 168 KiB

Open AccessEditorial

Editorial for Special Issue “Fluid Inclusion Characteristic of the Gold Deposit and Its Implication for Ore Genesis”

by Vsevolod Yu. Prokofiev

Minerals 2020, 10(3), 240; https://doi.org/10.3390/min10030240 - 06 Mar 2020

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Abstract

Fluid inclusions provide valuable information on the composition and physical and chemical parameters of mineral-forming hydrothermal fluids [...] Full article

(This article belongs to the Special Issue Fluid Inclusion Characteristic of the Gold Deposits and Its Implication for Ore Genesis)

Research

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16 pages, 6513 KiB

Open AccessArticle

Fluid Inclusion Characteristics of the Kışladağ Porphyry Au Deposit, Western Turkey

by Nurullah Hanilçi, Gülcan Bozkaya, David A. Banks, Ömer Bozkaya, Vsevolod Prokofiev and Yücel Öztaş

Minerals 2020, 10(1), 64; https://doi.org/10.3390/min10010064 - 13 Jan 2020

Cited by 6 | Viewed by 4548

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 [...] Read more.

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 T_h 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 T_h 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 Kışladağ porphyry gold deposit. Full article

(This article belongs to the Special Issue Fluid Inclusion Characteristic of the Gold Deposits and Its Implication for Ore Genesis)

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26 pages, 6319 KiB

Open AccessArticle

Contrasting Fluids in the Svetlinsk Gold-Telluride Hydrothermal System, South Urals

by Olga Vikent’eva, Vsevolod Prokofiev, Andrey Borovikov, Sergey Kryazhev, Elena Groznova, Mikhail Pritchin, Ilya Vikentyev and Nikolay Bortnikov

Minerals 2020, 10(1), 37; https://doi.org/10.3390/min10010037 - 30 Dec 2019

Cited by 17 | Viewed by 3247

Abstract

The large gold-telluride Svetlinsk deposit (~135 t Au) is considered to be a nontraditional one in the Urals and its origin is debated. A specific feature of the deposit is the abundance of various tellurides, such as tellurides of Fe, Ni, Pb, Sb, [...] Read more.

The large gold-telluride Svetlinsk deposit (~135 t Au) is considered to be a nontraditional one in the Urals and its origin is debated. A specific feature of the deposit is the abundance of various tellurides, such as tellurides of Fe, Ni, Pb, Sb, Bi, Ag, and Au. The new data of microthermometry, Raman spectroscopy, LA-ICP-MS, and crush-leach analysis (gas and ion chromatography, ICP-MS) for fluid inclusions as well as O-isotope data for quartz were obtained for the construction of PTX parameters of ore-formation and fluid sources in the deposit. Mineralisation was formed at a wide range of temperature and pressure (200–400 °C, 1–4 kbar) and from contrasting fluids with multiple sources. At the early stages, the magmatic fluid evolved during its ascent and phase separation and the fluid derived from the host rock decarbonation and dehydration were involved in the hydrothermal system. In addition, mantle-derived fluid might be involved in the ore-forming process during gold-telluride precipitation as well as heated meteoric waters during the late stages. Early fluids were rich in H₂S, S⁰, and CH₄, while the Au-Te mineralisation was formed from N₂-rich fluid. Full article

(This article belongs to the Special Issue Fluid Inclusion Characteristic of the Gold Deposits and Its Implication for Ore Genesis)

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11 pages, 438 KiB

Open AccessArticle

Accurate Calculation Procedure for V-x Parameters of Hydrothermal Gold Ore Fluid Inclusions

by Shixiang Yang, Rui Sun, Xiqiang Liu, Zhao Liu and Jingyuan Wen

Minerals 2019, 9(11), 673; https://doi.org/10.3390/min9110673 - 31 Oct 2019

Cited by 1 | Viewed by 2325

Abstract

Determining the V-x parameters of H₂O–NaCl–CO₂ fluid inclusions (total density of inclusions, gas content, homogenization pressure, etc.) is of great value for the exploration of hydrothermal deposits. However, previous accurate calculation methods are only applicable to H₂O–NaCl–CO₂ [...] Read more.

Determining the V-x parameters of H₂O–NaCl–CO₂ fluid inclusions (total density of inclusions, gas content, homogenization pressure, etc.) is of great value for the exploration of hydrothermal deposits. However, previous accurate calculation methods are only applicable to H₂O–NaCl–CO₂ fluid inclusions with homogenization temperature above 300 °C and CO₂ phase homogenization temperature above the CO₂ clathrate melting temperature. In this paper, a new calculation method is proposed to accurately solve the V-x parameters of H₂O–NaCl–CO₂ fluid inclusions with complete homogenization temperature lower than 300 °C. The algorithm first determines the salinity of inclusions with respect to the melting temperature of CO₂ clathrate and the partial homogenization temperature of the CO₂ phase and then determines the internal pressure of inclusions when CO₂ clathrate is completely melted. The V-x parameters of the inclusions are then iteratively solved. The new algorithm does not require a visual estimation of the volume fraction of the CO₂ phase as an input parameter. It is possible to avoid the significant error brought about by traditional method of calculating the inclusion V-x parameters involving visual estimation of the CO₂ phase volume fraction. A computer program is developed on the basis of the new method and is applied to the analysis of fluid inclusions in medium and low temperature hydrothermal gold ore. Full article

(This article belongs to the Special Issue Fluid Inclusion Characteristic of the Gold Deposits and Its Implication for Ore Genesis)

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22 pages, 4070 KiB

Open AccessFeature PaperArticle

Geochemical and Geochronological Discrimination of Biotite Types at the Detour Lake Gold Deposit, Canada

by Renelle Dubosq, David A. Schneider, Alfredo Camacho and Christopher J.M. Lawley

Minerals 2019, 9(10), 596; https://doi.org/10.3390/min9100596 - 30 Sep 2019

Cited by 6 | Viewed by 6539

Abstract

The Detour Lake deposit is at a faulted contact between mafic volcanic and siliciclastic to volcaniclastic rocks, differing from other orogenic Au deposits in the dominantly greenschist facies Abitibi region, by possessing amphibolite facies assemblages. Consequently, typical indicator minerals for mineralization, like secondary [...] Read more.

The Detour Lake deposit is at a faulted contact between mafic volcanic and siliciclastic to volcaniclastic rocks, differing from other orogenic Au deposits in the dominantly greenschist facies Abitibi region, by possessing amphibolite facies assemblages. Consequently, typical indicator minerals for mineralization, like secondary biotite, may not be useful for locating ore zone, due to the challenge of distinguishing hydrothermal versus metamorphic and magmatic phases. Herein, geochemical and ⁴⁰Ar/³⁹Ar geochronological data are presented for biotite from mineralized and barren (distal) magmatic rocks to characterize potential geochemical and geochronological variations between biotite types. Petrological observations reveal four biotite types: (1) Biotite hosted in mineralized, sulphidized quartz-calcite veins, (2) halo biotite at the margins of the aforementioned veins; (3) host rock biotite defining the foliation within the mafic volcanic rocks of the deposit; and (4) biotite defining the foliation within the barren meta-plutonic host rocks. Chemical analysis reveals a lower Ti- and higher Mg-content of mineralized biotite types, indicative of secondary hydrothermal processes. ⁴⁰Ar/³⁹Ar ages for all biotite types (2600–2390 Ma) post-date the main syn-deformation mineralization event at Detour Lake (≤2700 Ma). These results suggest chemical variations within biotite are due to a post-mineralization hydrothermal event, thus biotite should be used cautiously as a vector for gold mineralization in amphibolite facies terranes. Full article

(This article belongs to the Special Issue Fluid Inclusion Characteristic of the Gold Deposits and Its Implication for Ore Genesis)

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29 pages, 7148 KiB

Open AccessArticle

Ore Genesis of Shanmen Ag Deposit in Siping Area of Southern Jilin Province, NE China: Constraints from Fluid Inclusions and H-O, S, Pb Isotopes

by Xinhao Sun, Yunsheng Ren, Peng Cao, Yujie Hao and Yu Gao

Minerals 2019, 9(10), 586; https://doi.org/10.3390/min9100586 - 27 Sep 2019

Cited by 7 | Viewed by 3448

Abstract

The Shanmen Ag deposit, located in the southeastern part of the Siping area, Jilin Province, is one of the large-scale Ag deposits in Northeastern (NE) China. Almost all Ag orebodies, Ag-bearing quartz-sulfide veins are strictly controlled by NE-trending faults or brittle fractures and [...] Read more.

The Shanmen Ag deposit, located in the southeastern part of the Siping area, Jilin Province, is one of the large-scale Ag deposits in Northeastern (NE) China. Almost all Ag orebodies, Ag-bearing quartz-sulfide veins are strictly controlled by NE-trending faults or brittle fractures and are hosted in the Yanshanian monzonite and quartz diorite. In terms of deposit geology, three mineralization stages are recognized: the pyrite-quartz stage (I), the quartz-Ag-polymetallic sulfide stage (II), and the carbonate-quartz stage (III). The research results of the fluid inclusions in the different stages indicate that the early stage (Stage I) mainly contains three types of fluid inclusions: liquid-rich two-phase (L-type), vapor-rich two-phase (V-type), and CO₂ aqueous multi-phase (C-type). The fluid belongs to a medium–high temperature and medium–low salinity H₂O-NaCl-CO₂ system and has boiling characteristics. The middle stage (Stage II) is mainly characterized by liquid-rich two-phase (L-type) and vapor-rich two-phase (V-type) inclusions, in which the mixing of fluids of different nature leads to the escape of CO₂. Only liquid-rich two-phase (L-type) inclusions are distinguished in the late stage (Stage III). The fluids of two later stages belong to the medium-low-temperature and low-salinity H₂O-NaCl system. Homogenization temperatures from the early to late stages range from 272.2 to 412.5 °C, 124.1 to 313.3 °C, and 128.6 to 224 °C, respectively. Fluid salinities in the early to late stages range from 1.6 to 12.1, 1.4 to 8.9, and 0.4 to 5.8 wt.% NaCl equivalent, respectively. The gradually decreasing trends of homogenization temperatures and salinities and the reduction in the CO₂ content indicate that the release of CO₂ and the low-temperature environment are important causes of the precipitation of Ag-bearing minerals. The δ¹⁸O_H2O values of the ore-bearing quartz veins in the different stages range from −3.7 to +8.1‰, and the δD values of fluid inclusions in the quartz range from −113 to −103‰, indicating that the initial ore-forming fluid was mainly derived from magma and that the input of meteoric water gradually increased during the mineralization process. The δ³⁴S values (ranging from −11.4‰ to +1.8‰) and Pb isotope compositions (²⁰⁶Pb/²⁰⁴Pb = 18.143–18.189, ²⁰⁷Pb/²⁰⁴Pb = 15.543–15.599, ²⁰⁸Pb/²⁰⁴Pb = 38.062–38.251) of sulfides suggest that the ore-forming materials have mixed mantle and crustal sources. Therefore, we propose that the release of CO₂ and the low-temperature environment are important conditions for silver minerals precipitation, and the mixing of fluids of different nature is the dominant mechanism causing precipitation. The Shanmen Ag deposit can be classified as an intrusion-related medium–low temperature hydrothermal vein-type deposit. Full article

(This article belongs to the Special Issue Fluid Inclusion Characteristic of the Gold Deposits and Its Implication for Ore Genesis)

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23 pages, 7933 KiB

Open AccessFeature PaperArticle

Ore Genesis at the Jinchang Gold–Copper Deposit in Heilongjiang Province, Northeastern China: Evidence from Geology, Fluid Inclusions, and H–O–S Isotopes

by Shunda Li, Xuebing Zhang and Lingling Gao

Minerals 2019, 9(2), 99; https://doi.org/10.3390/min9020099 - 10 Feb 2019

Cited by 11 | Viewed by 4327

Abstract

The Jinchang gold–copper deposit is located in Eastern Heilongjiang Province, Northeastern China. The orebody comprises primarily hydrothermal breccias, quartz veins, and disseminated ores within granite, diorite, and granodiorite. Three paragenetic stages are identified: early quartz–pyrite–arsenopyrite (Stage 1), quartz–pyrite–chalcopyrite (Stage 2), and late quartz–pyrite–galena–sphalerite [...] Read more.

The Jinchang gold–copper deposit is located in Eastern Heilongjiang Province, Northeastern China. The orebody comprises primarily hydrothermal breccias, quartz veins, and disseminated ores within granite, diorite, and granodiorite. Three paragenetic stages are identified: early quartz–pyrite–arsenopyrite (Stage 1), quartz–pyrite–chalcopyrite (Stage 2), and late quartz–pyrite–galena–sphalerite (Stage 3). Gold was deposited during all three stages and Stage 1 was the major gold-producing stage. Copper is associated with the mineralization but has low economic value. Fluid inclusions (FIs) within the deposit are liquid-rich aqueous, vapor-rich aqueous, and daughter-mineral-bearing types. Microthermometric data for the FIs reveal decreasing homogenization temperatures (T_h) and salinities of the ore-forming fluids over time. The T_h for Stages 1–3 of the mineralization are 421–479, 363–408, and 296–347 °C, respectively. Stage 1 fluids in vapor-rich and daughter-mineral-bearing inclusions have salinities of 5.7–8.7 and 49.8–54.4 wt% NaCl equivalent, respectively. Stage 2 fluids in vapor-rich, liquid-rich, and daughter-mineral-bearing inclusions have salinities of 1.2–5.4, 9.5–16.0, and 43.3–48.3 wt% NaCl, respectively. Stage 3 fluids in liquid-rich and daughter-mineral-bearing inclusions have salinities of 7.9–12.6 and 38.3–42.0 wt% NaCl equivalent, respectively. The estimated trapping pressures are 160–220 bar, corresponding to an entrapment depth of 1.6–1.2 km in the paleo-water table. Oxygen and hydrogen isotope data (δ¹⁸O_V-SMOW = 8.6‰ to 11.4‰; δD_V-SMOW = −92.2‰ to −72.1‰) suggest that the ore-forming fluids were derived from magmatic fluids during the early stages of mineralization and subsequently incorporated meteoric water during the late stages. The sulfide minerals have δ³⁴S_VCDT values of 0.2‰–3.5‰, suggesting that the sulfur has a magmatic origin. The Jinchang deposit is a typical gold-rich gold–copper porphyry deposit. Full article

(This article belongs to the Special Issue Fluid Inclusion Characteristic of the Gold Deposits and Its Implication for Ore Genesis)

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33 pages, 15652 KiB

Open AccessArticle

The Tocantinzinho Paleoproterozoic Porphyry-Style Gold Deposit, Tapajós Mineral Province (Brazil): Geology, Petrology and Fluid Inclusion Evidence for Ore-Forming Processes

by Adriana Araújo Castro Lopes and Márcia Abrahão Moura

Minerals 2019, 9(1), 29; https://doi.org/10.3390/min9010029 - 05 Jan 2019

Cited by 9 | Viewed by 4461

Abstract

The Tocantinzinho gold deposit, located in the Tapajós Mineral Province, Amazonia, Brazil, is considered the largest gold deposit in the region. It is a stockwork-disseminated gold deposit, hosted in a 1982 ± 8 Ma hydrothermalized monzogranite of the Creporizão Intrusive Suite, with petrographic [...] Read more.

The Tocantinzinho gold deposit, located in the Tapajós Mineral Province, Amazonia, Brazil, is considered the largest gold deposit in the region. It is a stockwork-disseminated gold deposit, hosted in a 1982 ± 8 Ma hydrothermalized monzogranite of the Creporizão Intrusive Suite, with petrographic and geochemical characteristics of volcanic arc to post-collisional granites. Gold is mainly associated with phyllic alteration. Primary fluid inclusions trapped in the mineralization stages are H₂O–NaCl and unsaturated and homogenize either to the vapor or to the liquid with Th_(t) of 300–430 °C, salinity of 2–16 wt % NaCl eq. and density from 0.43 to 0.94 g/cm³. At these conditions, Au is expected to be transported as Au(HS)₂⁻ complexes and ore is deposited as the result of boiling in the first mineralizing stages and of mixing between magmatic fluid and meteoric water during the phyllic alteration. Compared with other deposits, Tocantinzinho has similarities with magmatic-hydrothermal oxidized calc-alkaline granite-related gold deposits classified as porphyry gold deposits but we classify as a porphyry-style gold deposit, as it lacks some characteristics of the Phanerozoic porphyry-type deposits. The results from this study can be used to elaborate and guide prospection models in Amazonia and in similar Proterozoic terrains. Full article

(This article belongs to the Special Issue Fluid Inclusion Characteristic of the Gold Deposits and Its Implication for Ore Genesis)

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Review

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38 pages, 2750 KiB

Open AccessReview

Physicochemical Parameters and Geochemical Features of Ore-Forming Fluids for Orogenic Gold Deposits Throughout Geological Time

by Vsevolod Yu. Prokofiev and Vladimir B. Naumov

Minerals 2020, 10(1), 50; https://doi.org/10.3390/min10010050 - 05 Jan 2020

Cited by 14 | Viewed by 6265

Abstract

This paper reviews data from numerous publications focused on the physicochemical parameters and chemical composition of ore-forming fluids from orogenic gold deposits formed during various geological epochs. The paper presents analysis of the distribution of the principal parameters of mineralizing fluids depending on [...] Read more.

This paper reviews data from numerous publications focused on the physicochemical parameters and chemical composition of ore-forming fluids from orogenic gold deposits formed during various geological epochs. The paper presents analysis of the distribution of the principal parameters of mineralizing fluids depending on the age of the mineralization. Some parameters of the fluids (their salinity and pressure) at orogenic gold deposits are demonstrated to systematically vary from older (median salinity 6.1 wt.%, median pressure 1680 bar) to younger (median salinity 3.6 wt.%, median pressure 1305 bar) deposits. The detected statistically significant differences between some parameters of mineralizing fluids at orogenic gold deposits are principally new information. The parameters at which mineralization of various age was formed are demonstrated to pertain to different depth levels of similar mineralization-forming systems. The fluid parameters of the most ancient deposits (which are mostly deeply eroded) correspond to the deepest levels of orogenic fluid systems. Hence, the detected differences in the salinity and pressure of the mineralizing fluids at orogenic deposits of different age reflect the vertical zoning of the mineralizing fluid systems. Full article

(This article belongs to the Special Issue Fluid Inclusion Characteristic of the Gold Deposits and Its Implication for Ore Genesis)

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