Magmatogene fluids of metal-bearing reefs in the Bushveld Complex, South Africa: Based on research data on fluid inclusions in quartz

Zhitova, L.M.; Kinnaird, Judith A.; Gora, M. P.; Shevko, E. P.

doi:10.1134/s1075701515050086

Cited by 15 publications

(8 citation statements)

References 41 publications

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“…Their salinity varies from high (60−70 wt % NaCl equiv) to moderate-to-low (20 to ∼7 wt % NaCl equiv) depending on the entrapment temperature. 17,18 Abundance of H 2 O-, Cl-, and F-bearing minerals crystallized in Norilsk ores in the vicinity of Au chalcogenides, chlorides, and intermetallic compounds suggests that the Au mineralization was related to postmagmatic hydrothermal stage, which took place at a temperature of 350 °C and below. 19 Nuggets and particles of native gold are often formed during volcanic eruptions and fumarolic activity.…”

Section: Introductionmentioning

confidence: 99%

Gold Transport in Hydrothermal Chloride-Bearing Fluids: Insights from in Situ X-ray Absorption Spectroscopy and ab Initio Molecular Dynamics

Тагиров

Trigub

Filimonova

et al. 2018

ACS Earth Space Chem.

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Chloride-bearing fluids are widespread in the Earth’s interior from low-temperature subsurface conditions to deep lithosphere. The concentration of chloride salts varies from diluted aqueous solutions to concentrated brines and anhydrous (dry) chloride melts beneath volcanoes. Here we report an investigation of the state of Au in hydrothermal chloride fluids and anhydrous melts by means of in situ X-ray absorption spectroscopy combined with ab initio molecular dynamics simulations and thermodynamic modeling. The experiments included registration of Au L3-edge X-ray absorption near edge structure/extended X-ray absorption fine structure spectra of Au-bearing fluids in the temperature range from 350 to 575 °C at pressures of 150–4500 bar. Spectra of Au dissolved in dry CsCl/NaCl/KCl + K2S2O8 melt were recorded at 650 °C. It was found that Au is coordinated by two Cl atoms (R Au–Cl = 2.25–2.28 Å). The alkali metal atoms (Me) were detected in the distant coordination sphere of Au at R Au‑Me = 3.3–4.1 Å. The alkali metal cations in the vicinity of Au–Cl complex partly compensate the positive charge located on Au and, by this way, affect the Au–Cl distance. An increase of the fluid pressure causes expansion of the second coordination sphere composed of the alkali metal cations, which leads to the increase of the positive Au charge and results in slight contraction of the first coordination sphere of Au. Accordingly, the transport of Au in high-temperature chloride-bearing natural ore-forming fluids of moderate to high densities (>0.3 g·cm–3) can be explicitly described by the formation of the AuCl2 – at any salt concentration from low-salinity fluids to hydrosaline liquids and anhydrous melts. In general, this means that the hydrothermal fluid chemistry simplifies with increasing temperature.

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Section: Introductionmentioning

confidence: 99%

Gold Transport in Hydrothermal Chloride-Bearing Fluids: Insights from in Situ X-ray Absorption Spectroscopy and ab Initio Molecular Dynamics

Тагиров

Trigub

Filimonova

et al. 2018

ACS Earth Space Chem.

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“…Thus, the crystallization of Fe 2 (OH) 3 Cl minerals could be an important transitional event for later ore-remobilization and ore-forming processes. This is supported by the fact that remobilization of magmatic ore minerals by post-magmatic fluids is known and well documented in several large intrusive complexes, such as the Bushveld Complex (Ballhaus and Stumpfl 1986;Zhitova 2016;Kawohl and Frimmel 2016), the Duluth Complex (Mogessie and Stumpfl 1992;Ripley 1990;Dahlberg and Saini-Eidukat 1991), and the Sudbury Complex (Hanley and Mungall 2003). In each of these complexes, the presence of ferrous hydroxychlorides was also reported.…”

Section: Discussionmentioning

confidence: 80%

Ferrous hydroxychlorides hibbingite [γ-Fe2(OH)3Cl] and parahibbingite [β-Fe2(OH)3Cl] as a concealed sink of Cl and H2O in ultrabasic and granitic systems

Koděra

Majzlan

Pollok

et al. 2022

American Mineralogist

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Ferrous hydroxychlorides are geochemically important, but less recognized, mineral species due to their extreme sensitivity to oxidation and hydration in contact with air (typically they convert to This is the peer-reviewed, final accepted version for American Mineralogist, published by the Mineralogical Society of America.The published version is subject to change. Cite as Authors (Year) Title. American Mineralogist, in press.

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“…This is another argument in favor of studying platinum-bearing gold deposits, of which the Natalkinskoe deposit is no exception. Information about the Pt content in the fluid is of particular value in view of the complex behavior of Pt and the heterogeneity of its distribution under the capture of gas-liquid inclusions, the composition of which is determined by LA-ICP-MS as a proxy of the ore fluid composition [47].…”

Section: Interval Of Masses (Mg)m (Mg)r (Mm)smentioning

confidence: 99%

Platinum Group Elements in Arsenopyrites and Pyrites of the Natalkinskoe Gold Deposit (Northeastern Russia)

et al. 2020

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The peculiarities of the distribution and binding forms of platinum group elements (Pt, Pd, Ru, Rh, Os and Ir) in the arsenopyrites and pyrites of the Natalkinskoe gold ore deposit (Northeastern Russia) were examined using atomic absorption spectrometry with analytical data selections for single crystals (AAS-ADSSC), a “phase” chemical analysis (PCA) based on AAS of different size-fractions of minerals, scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDX) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The arsenopyrites and pyrites of the Natalkinskoe gold deposit were found to concentrate not only Au but also platinum group elements (PGEs) such as Pt, Pd, Ru and Rh. The PCA showed that the highest contents (in ppm) were found in the monofractions of arsenopyrite—Pt up to 128, Pd up to 20, Ru up to 86 and Rh up to 21—and comparably lower in monofractions of pyrite—Pt to 29, Pd to 15, Ru to 58 and Rh to 5.9. The AAS-ADSSC method revealed two forms of uniformly distributed Pt, Pd and Ru corresponding to the chemically bound element in the structure of the mineral and in the superficial non-autonomous phase (NAP). The superficially bound form dominates over the structural form and presumably exists in a very thin surface layer of the crystal (~100–500 nm). The maximum contents of these PGE, chemically bound in the structure of arsenopyrite, reached values of (in ppm) 48, 5.9 and 48; and in pyrite structure, 68, 5.2 and 34 for Pt, Pd and Ru respectively. The contents of Pt, Pd and Ru related to NAP on the surface of the crystal were significantly higher and amounted (in ppm) for arsenopyrite to 714, 114 and 1083; and for pyrite 890, 62 and 690 for Pt, Pd and Ru, respectively. Preliminary results for the Rh form in arsenopyrite crystals suggest that the surface-related form (154–678 ppm) is more abundant than the structural form (17–45 ppm). Data from studying the surfaces of sulphide minerals by SEM-EDX and LA-ICP-MS confirmed the presence of Pt, Pd, Ru and Rh on the surface of arsenopyrite and pyrite crystals. These methods generated primary data on the content of Os and Ir in arsenopyrite and pyrite in the surface layer. The maximum content of Os and Ir found in arsenopyrites was up to 0.7 wt%. PGE-enriched fluids (up to ~3 ppm Pt) may exist in the gold ore deposit. It is assumed that there is a common mechanism of impurities uptake associated with the active role of the crystal surface and surface defects for gold-bearing arsenopyrites and pyrites. The surface enrichment is due to peculiarities in the crystal growth mechanism through the medium of NAP and the dualism of the element distribution coefficient in the system of mineral–hydrothermal solution, which is higher for NAP, compared to the volume of the crystal. Although mineral forms of Pt, Pd, Ru, Rh, Os and Ir have not been found at the Natalkinskoe gold deposit, their existence in the form of nano-scale particles is not excluded. This follows from the evolutionary model of surficial NAPs, assuming their partial transformation and aggregation with the formation of nano- and micro-sized autonomous phases of trace elements. The presence of PGE in the ores and the possibility of their extraction significantly increase the quality and value of the extracted raw gold materials at the Natalkinskoe deposit, and adds to the list of known platiniferous ore formations.

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Magmatogene fluids of metal-bearing reefs in the Bushveld Complex, South Africa: Based on research data on fluid inclusions in quartz

Cited by 15 publications

References 41 publications

Gold Transport in Hydrothermal Chloride-Bearing Fluids: Insights from in Situ X-ray Absorption Spectroscopy and ab Initio Molecular Dynamics

Gold Transport in Hydrothermal Chloride-Bearing Fluids: Insights from in Situ X-ray Absorption Spectroscopy and ab Initio Molecular Dynamics

Ferrous hydroxychlorides hibbingite [γ-Fe2(OH)3Cl] and parahibbingite [β-Fe2(OH)3Cl] as a concealed sink of Cl and H2O in ultrabasic and granitic systems

Platinum Group Elements in Arsenopyrites and Pyrites of the Natalkinskoe Gold Deposit (Northeastern Russia)

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