Hydrothermal Fluid and Metal Transportation: Fluid Inclusions and Ore-Forming Process

A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Mineral Deposits".

Deadline for manuscript submissions: closed (30 April 2023) | Viewed by 5408

Special Issue Editors


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Guest Editor
School of Civil and Resource Engineering, University of Science and Technology Beijing, Beijing 100083, China
Interests: fluid and melt inclusion; REE deposits; lead–zinc deposits

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Guest Editor
Camborne School of Mines, University of Exeter, Penryn, Cornwall TR10 9FE, UK
Interests: economic geology; mineral exploration; orebody knowledge; geometallurgy; mining geology
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
School of Civil and Resource Engineering, University of Science and Technology Beijing, Beijing 100083, China
Interests: experimental geochemistry; REE mineralizaiton
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Most endogenetic mineral deposits are directly or indirectly genetically related to hydrothermal fluids. Fluid, melt-fluid, and melt inclusions record the origin and evolution of fluids as well as the transition from melts to fluids. Therefore, they provide important constraints on the mechanics of metal transportation and precipitation.

In addition to fluid inclusions, hydrothermal alteration, the result of fluid–rock interaction, also provides geological records on the physico-chemical properties of fluids. The alteration zonation is one of the most important features of an ore-forming system and is widely used as the indicator for mineral exploration.

Experimental and thermodynamic geochemistry are top-down approaches that explore the chemical basis behind hydrothermal ore-forming processes and critical in understanding the nature of the hydrothermal fluids and mechanisms controlling the dissolution and precipitation of metals.

This Special Issue is organized into four sections:

Section 1. Describe the characteristics and evolution of ore-forming fluids: analytical methods, data analysis, and case studies of hydrothermal deposits are discussed.

Section 2. Describe alteration and its application to exploration: case studies, mechanics of the formation of hydrothermal alteration, and its application to exploration are discussed.

Section 3. Describe experimental and thermodynamic simulations of hydrothermal fluids: The solubility of metals in hydrothermal fluids, element speciation in aqueous fluids, the ligand of metal transportation, and the geochemical modeling of hydrothermal fluids are discussed.

Section 4. Describe controls and mechanisms of fluid flow: structural and lithological controls, controls to grade distribution, and ore shoot/pay zone formation are discussed.

This Special Issue aims to present the role of hydrothermal fluids during the formation of mineral deposits and the mechanisms of element dissolution and precipitation.

Prof. Dr. Yuling Xie
Dr. Simon Dominy
Prof. Dr. Richen Zhong
Guest Editors

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Keywords

  • fluid inclusion
  • ore-forming process
  • metal transportation
  • hydrothermal alteration
  • element speciation

Published Papers (3 papers)

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Research

40 pages, 17094 KiB  
Article
Magmatic–Hydrothermal Transport of Metals at Arc Plutonic Roots: Insights from the Ildeus Mafic–Ultramafic Complex, Stanovoy Suture Zone (Russian Far East)
by Pavel Kepezhinskas, Nikolai Berdnikov, Nikita Kepezhinskas, Valeria Krutikova and Ivan Astapov
Minerals 2023, 13(7), 878; https://doi.org/10.3390/min13070878 - 29 Jun 2023
Cited by 3 | Viewed by 1497
Abstract
The Ildeus mafic–ultramafic complex represents plutonic roots of a Triassic magmatic arc tectonically emplaced into the thickened uppermost crust beneath the Mesozoic Stanovoy collided margin. The mafic–ultramafic complex cumulates host Ni-Co-Cu-Pt-Ag-Au sulfide-native metal-alloy mineralization produced through magmatic differentiation of subduction-related primary mafic melt. [...] Read more.
The Ildeus mafic–ultramafic complex represents plutonic roots of a Triassic magmatic arc tectonically emplaced into the thickened uppermost crust beneath the Mesozoic Stanovoy collided margin. The mafic–ultramafic complex cumulates host Ni-Co-Cu-Pt-Ag-Au sulfide-native metal-alloy mineralization produced through magmatic differentiation of subduction-related primary mafic melt. This melt was sourced in the metal-rich sub-arc mantle wedge hybridized by reduced high-temperature H-S-Cl fluids and slab/sediment-derived siliceous melts carrying significant amounts of Pt, W, Au, Ag, Cu and Zn. Plutonic rocks experienced a pervasive later-stage metasomatic upgrade of the primary sulfide–native metal–alloy assemblage in the presence of oxidized hydrothermal fluid enriched in sulfate and chlorine. The new metasomatic assemblage formed in a shallow epithermal environment in the collided crust includes native gold, Ag-Au, Cu-Ag and Cu-Ag-Au alloys, heazlewoodite, digenite, chalcocite, cassiterite, galena, sphalerite, acanthite, composite Cu-Zn-Pb-Fe sulfides, Sb-As-Se sulfosalts and Pb-Ag tellurides. A two-stage model for magmatic–hydrothermal transport of some siderophile (W, Pt, Au) and chalcophile (Cu, Zn, Ag) metals in subduction–collision environments is proposed. Full article
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36 pages, 12893 KiB  
Article
Magmatic-Hydrothermal Fluid Processes of the Sn-W Granites in the Maniema Province of the Kibara Belt (KIB), Democratic Republic of Congo
by Douxdoux Kumakele Makutu, Jung Hun Seo, Insung Lee, Jihye Oh, Pilmo Kang, Albert Tienge Ongendangenda and Frederic Mwanza Makoka
Minerals 2023, 13(4), 458; https://doi.org/10.3390/min13040458 - 24 Mar 2023
Cited by 1 | Viewed by 2282
Abstract
The Kibara belt (KIB) in the Maniema province hosts orebodies bearing cassiterite-wolframite, which are associated with equigranular to pegmatitic late Mesoproterozoic (1094–755 Ma) granites and Sn-W bearing quartz veins that cut through metasedimentary country rocks. Alteration assemblages of muscovite-quartz (±topaz-fluorite-tourmaline) occur in the [...] Read more.
The Kibara belt (KIB) in the Maniema province hosts orebodies bearing cassiterite-wolframite, which are associated with equigranular to pegmatitic late Mesoproterozoic (1094–755 Ma) granites and Sn-W bearing quartz veins that cut through metasedimentary country rocks. Alteration assemblages of muscovite-quartz (±topaz-fluorite-tourmaline) occur in the granites, and muscovite-sericite-quartz occurs in Sn-W quartz veins. Petrographic analyses, including cathodoluminescence (SEM-CL) on cassiterite grains, reveal two types of cassiterite: yellow transparent cassiterite (lighter under SEM-CL: type I) and dark translucent cassiterite (darker under SEM-CL: type II). These types are organized in micro-textures as oscillatory (growth) zones and replacement zones (type II replaces type I). Unlike cassiterite, wolframite is texturally homogenous. LA-ICP-MS results reveal that type II cassiterite is relatively enriched in Fe, Al, Ga, In, As, Pb, Zn, and U, whereas type I is enriched in V, Ti, Zr, Ta, Hf, and Nb. Contrasting Ce anomaly values in the cassiterite types suggest a transition of redox potentials during the Sn precipitation. Fluid inclusion assemblages (FIAs) in quartz, fluorite, and cassiterite are dominantly aqueous, liquid- or vapor-rich, and rarely carbonic-bearing aqueous inclusions. These often texturally coexist in a single “boiling” assemblage in granites. Raman spectroscopy on the bubble part of fluid inclusions in quartz and cassiterite shows various gas species, including CO2, CH4, N2, and H2. Boiling assemblages in the granites suggest that fluid phase separation occurred at about 380–610 bars, which is about 1–2 km (lithostatic) or 3–5 km (hydrostatic) in apparent paleodepth. FIAs in the granites show ranges of salinities of 4–23 wt.% (NaCl equivalent) and homogenization temperatures (Th) of 190–550 °C. FIAs hosted in cassiterite displayed distinctively lower and narrower ranges of salinities of 2–10 wt.% and Th of 220–340 °C compared to the FIAs hosted in quartz in the granites (salinity of 4–23 wt.%, Th of 190–550 °C) and the quartz veins (salinity of 1–23 wt.%, Th of 130–350 °C). This suggests a less salinized and cooler fluid during the cassiterite precipitation. We suggest that magmatic-derived Sn-W bearing fluids be mixed with less saline and cooler aqueous fluids, possibly meteoric water, during the major cassiterite and possibly wolframite depositions in the KIB. This is based on (1) temperature and salinities, (2) hydrothermal alterations, (3) cassiterite micro-textures, and (4) trace element distributions. Full article
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12 pages, 2956 KiB  
Article
The Immobility of Uranium (U) in Metamorphic Fluids Explained by the Predominance of Aqueous U(IV)
by Min Zhang, Richen Zhong, Chang Yu and Hao Cui
Minerals 2023, 13(3), 427; https://doi.org/10.3390/min13030427 - 17 Mar 2023
Viewed by 1231
Abstract
The solubility of uranium (U) in hydrothermal fluid is thought to be controlled by oxidation. In general, uranium is mainly transported as U(VI) in oxidized fluid, but precipitated as U(IV) in reduced fluid. However, many geological observations indicate that metamorphic fluids, which are [...] Read more.
The solubility of uranium (U) in hydrothermal fluid is thought to be controlled by oxidation. In general, uranium is mainly transported as U(VI) in oxidized fluid, but precipitated as U(IV) in reduced fluid. However, many geological observations indicate that metamorphic fluids, which are buffered by metamorphic rocks with oxidized protoliths such as oxidized pelite or altered marine basalt, are not enriched in U. To explore the reason of the low solubility of U in metamorphic fluids, we simulated the hydrous speciation and solubility of U in fluids that are in equilibrium with rocks. The simulations were conducted at pressure–temperature (P-T) conditions of greenschist and amphibolite facies metamorphism. The results show that U is mainly dissolved as U(IV), instead of U(VI), in metamorphic fluids. The solubility of U remains at a low level of ~10−12 molal, and is not significantly influenced by metamorphic temperature, pressure, and fluid salinity. This result is consistent with geological observations and, thus, can explain the low-U nature of natural metamorphic fluids. The simulation also shows high solubility of U(VI) (1.3 × 10−7 molal) in oxidized pelite-buffered fluids at low temperature (<250 °C), consistent with the geological fact that U can be mobilized by low-temperature geofluids. Full article
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