The Mineral Alteration Patterns under High- to Low-Temperature in Geothermal Fields

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

Deadline for manuscript submissions: closed (31 July 2021) | Viewed by 14721

Special Issue Editors


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Guest Editor
Department of Geology and Andean Geothermal Center of Excellence (CEGA), Facultad Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago, Chile
Interests: petrology; geochemistry; geochronology; mineral chemistry; hydrothermal alteratiosn; very low-grade metamorphism; geothermal systems
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Guest Editor
Institut de Chimie des Milieux et des Matériaux de Poitiers, Universite de Poitiers, UMR CNRS 7285, 86073 Poitiers, France
Interests: hydrothermal alteration; geothermal systems; clay minerals; heat–fluid–rock interactions
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The mineral alteration patterns under high- to low-temperature conditions in active and fossil geothermal fields provide challenging topics that aim to understand heat–fluid–rock interaction processes. Geothermal systems allow us to understand and quantify heat–fluid–rock interactions in different geotectonic settings. Most, if not all, of these processes occur under thermodynamic conditions out of equilibrium, involving, among other geological processes, mineral dissolution, precipitation, recrystallisation and chemical transfer. Moreover, all these geological processes occur in a short time span—only several thousand years—with strong structural control, dominated by permeability differences between various affected geological units.

Under this scenario, mineral crystal chemistry in these high- to low-temperature systems is useful for constraining P-T-t-X conditions of these heat–fluid–rock processes. Remarkable advances have been made concerning diagenetic  conditions and reaction progress in clay minerals. However, results obtained for sedimentary basins cannot be directly applied to geothermal systems due to different dynamics. Therefore, contradictory results have been observed in detailed clay mineralogical studies carried out in active geothermal systems.

Contrastingly, the improvement of accuracy and resolution of advanced analytical techniques offered a new vision of how hot fluid interacts with rocks and how hydrothermal alteration mineralogy in high- to low-geothermal systems is formed.

Important and exciting advanced contributions of high- to low-temperature hydrothermal mineralogy in geothermal systems are expected by publishing this Special Issue with contributions from a broad field audience.

Prof. Dr. Diego Morata
Prof. Dr. Patricia Patrier-Mas
Guest Editors

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Keywords

  • Clay Minerals
  • Reaction progress
  • Mineral chemistry
  • Active geothermal systems
  • Geochronological dating
  • Fluid-flow-fractures

Published Papers (6 papers)

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Research

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26 pages, 11994 KiB  
Article
The Hydrothermal Alteration of the Cordón de Inacaliri Volcanic Complex in the Framework of the Hidden Geothermal Systems within the Pabelloncito Graben (Northern Chile)
by Santiago Nicolás Maza, Gilda Collo, Diego Morata, Carolina Cuña-Rodriguez, Marco Taussi and Alberto Renzulli
Minerals 2021, 11(11), 1279; https://doi.org/10.3390/min11111279 - 18 Nov 2021
Cited by 3 | Viewed by 2079
Abstract
Detailed mineralogical analyses in areas with surface hydrothermal alteration zones associated with recent volcanism (<1 Ma) in the Central Andean Volcanic Zone could provide key information to unravel the presence of hidden geothermal systems. In the Cordón de Inacaliri Volcanic Complex, a geothermal [...] Read more.
Detailed mineralogical analyses in areas with surface hydrothermal alteration zones associated with recent volcanism (<1 Ma) in the Central Andean Volcanic Zone could provide key information to unravel the presence of hidden geothermal systems. In the Cordón de Inacaliri Volcanic Complex, a geothermal field with an estimated potential of ~1.08 MWe·km2 has been recently discovered. In this work, we focus on the hydrothermal alteration zones and discharge products of this area, with the aim to reconstruct the geological processes responsible for the space-time evolution leading to the geothermal records. We identified (1) discharge products associated with acid fluids that could be related to: (i) acid-sulfate alteration with alunite + kaolinite + opal CT + anatase, indicating the presence of a steam-heated blanket with massive fine-grained silica (opal-CT), likely accumulated in mud pots where the intersection of the paleowater table with the surface occurred; (ii) argillic alteration with kaolinite + hematite + halloysite + smectite + I/S + illite in the surrounding of the acid-sulfate alteration; and (2) discharge products associated with neutral-alkaline fluids such as: (i) discontinuous pinnacle-like silica and silica deposits with laterally developed coarse stratification which, together with remaining microorganisms, emphasize a sinter deposit associated with alkaline/freshwater/brackish alkaline-chlorine water bodies and laterally associated with (ii) calcite + aragonite deriving from bicarbonate waters. The scarce presence of relics of sinter deposits, with high degree crystallinity phases and diatom remnants, in addition to alunite + kaolinite + opal CT + anatase assemblages, is consistent with a superimposition of a steam-heated environment to a previous sinter deposit. These characters are also a distinguishing feature of paleosurface deposits associated with the geothermal system of the Cordón de Inacaliri Volcanic Complex. The presence of diatoms in heated freshwater bodies at 5100 m a.s.l. in the Atacama Desert environment could be related with the last documented deglaciation in the area (~20–10 ka), an important factor in the recharge of the hidden geothermal systems of the Pabelloncito graben. Full article
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14 pages, 3913 KiB  
Article
Mineralogical Evolution of the Cretaceous Strata in the Songliao Basin, Northeastern China: Implications for Thermal History and Paleoenvironmental Evolution
by Tian Dong, Yuan Gao, He Huang, Xing Tian, Qian Yang, Yuyin Li, Lu Niu and Yongqiang Cao
Minerals 2021, 11(10), 1101; https://doi.org/10.3390/min11101101 - 08 Oct 2021
Cited by 3 | Viewed by 1421
Abstract
The Songliao Basin in northeastern China is one of the largest and longest-lived Cretaceous sedimentary basins enriched in petroleum and geothermal resources worldwide. Although the modern Songliao Basin has a high geothermal gradient, the geological thermal history of the basin has not been [...] Read more.
The Songliao Basin in northeastern China is one of the largest and longest-lived Cretaceous sedimentary basins enriched in petroleum and geothermal resources worldwide. Although the modern Songliao Basin has a high geothermal gradient, the geological thermal history of the basin has not been well constrained. The SK-2 drilling program, as the second stage of the International Continental Drilling Project of Cretaceous Songliao Basin, is for recovering extensive Early Cretaceous terrestrial strata and providing valuable materials for decoding the mineralogical evolution and the paleoenvironmental changes. Here, we present whole-rock and clay mineralogical analysis on 72 core samples covering 3346–5705 m of the Shahezi Formation in the SK-2 borehole. The whole-rock minerals mainly include clay minerals, quartz, plagioclase, as well as some calcite, K-feldspar, siderite, and pyrite. The clay mineral assemblages include illite, chlorite, and illite–smectite interlayer minerals. Above 4500 m, clay minerals are dominated by illite and illite–smectite interlayers. Below 4500 m, more plagioclase, K-feldspar, and calcite are present, while illite–smectite interlayers are completely replaced by illite. The whole-rock and clay mineralogical evolution of the Shahezi Formation is primarily controlled by thermal diagenesis, although paleoenvironmental change may act as a minor contribution. Combined with published data from the Upper Cretaceous in SK-1 cores, we infer that Cretaceous greenhouse climatic and environmental changes left fingerprints on whole-rock and clay mineralogical assemblages and that the Songliao Basin reached a maximum burial depth and a peak of thermal evolution at the end of the Cretaceous. Full article
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30 pages, 7580 KiB  
Article
Contribution of the Paragenetic Sequence of Clay Minerals to Re-Examination of the Alteration Zoning in the Krafla Geothermal System
by David Escobedo, Patricia Patrier, Daniel Beaufort, Benoit Gibert, Léa Levy, Nathaniel Findling and Annette Mortensen
Minerals 2021, 11(9), 935; https://doi.org/10.3390/min11090935 - 27 Aug 2021
Cited by 2 | Viewed by 2358
Abstract
This paper revisits the clay mineralogy of the “smectite” alteration zone in the Krafla geo-thermal field via the study of an exploratory well in which temperatures range from 40 °C to 215 °C. The clay alteration consists of several mineral assemblages superimposed in [...] Read more.
This paper revisits the clay mineralogy of the “smectite” alteration zone in the Krafla geo-thermal field via the study of an exploratory well in which temperatures range from 40 °C to 215 °C. The clay alteration consists of several mineral assemblages superimposed in time and space, resulting from different stages of water-rock interaction. Trioctahedral clay minerals (chlorite, corrensite and smectite) are observed throughout the studied section. These minerals can form in nearly closed systems as replacements of groundmass minerals/glass after interactions with resident and nearly stagnant fluids not far from chemical equilibrium (neutral to basic pH conditions) or from direct precipitation from geothermal fluids. They are locally superimposed by Al clay phases (smectite, illite/smectite and kaolinite), which result from intense leaching of the host rocks due to their interaction with low pH fluids under strong W/R ratios. The absence of mineralogical zoning is explained by the fact that hydrothermal alteration is strongly dependent on very recent hydrodynamics. The current fluid circulation generates trioctahedral clays at depth that cannot be distinguished from pervasive earlier alteration. The only easily detectable signature of current activity and the most relevant signature for geothermal exploration is the presence of Al dioctahedral phases since it indicates leaching and intense hydrothermal activity. Full article
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21 pages, 6806 KiB  
Article
Application of the Mineralogy and Mineral Chemistry of Carbonates as a Genetic Tool in the Hydrothermal Environment
by Javier Carrillo-Rosúa, Salvador Morales-Ruano, Stephen Roberts, Diego Morata and Mauricio Belmar
Minerals 2021, 11(8), 822; https://doi.org/10.3390/min11080822 - 29 Jul 2021
Cited by 3 | Viewed by 2463
Abstract
The mineralogy and mineral chemistry of carbonates from various hydrothermal deposits, including volcanic-hosted Au-Cu epithermal, “Chilean Manto-type” Cu(-Ag), stratabound Mn, and Ag-Ba vein deposits from Spain and Chile, were investigated. Dolomite-ankerite (±siderite) was found in variable amounts within the epithermal deposits and associated [...] Read more.
The mineralogy and mineral chemistry of carbonates from various hydrothermal deposits, including volcanic-hosted Au-Cu epithermal, “Chilean Manto-type” Cu(-Ag), stratabound Mn, and Ag-Ba vein deposits from Spain and Chile, were investigated. Dolomite-ankerite (±siderite) was found in variable amounts within the epithermal deposits and associated hydrothermal alteration, whereas calcite was found either within barren veins or disseminated within the regional alteration. Calcite is the major gangue phase within the stratabound deposits, which tend to lack dolomite/ankerite and siderite. Carbonates precipitated from hydrothermal ore fluids are typically Mn-rich, up to 3.55 at. % in siderite, 2.27 at. % in dolomite/ankerite, and 1.92 at. % in calcite. In contrast, calcite related to very low-grade metamorphism or regional low-temperature alteration is Mn-poor but sometimes Mg-rich, possibly related to a higher temperature of formation. Chemical zonation was observed in the hydrothermal carbonates, although no unique pattern and chemical evolution was observed. This study suggests that the chemical composition of carbonates, especially the Mn content, could be a useful vector within ore-forming hydrothermal systems, and therefore constitutes a possible tool in geochemical exploration. Furthermore, Mn-poor calcites detected in some deposits are suggested to be linked with a later episode, maybe suggesting a predominance of meteoric waters, being not related to the main ore stage formation, thus avoiding misunderstanding of further isotopic studies. Full article
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25 pages, 6446 KiB  
Article
Clay Mineralogy: A Signature of Granitic Geothermal Reservoirs of the Central Upper Rhine Graben
by Carole Glaas, Patricia Patrier, Jeanne Vidal, Daniel Beaufort and Albert Genter
Minerals 2021, 11(5), 479; https://doi.org/10.3390/min11050479 - 30 Apr 2021
Cited by 7 | Viewed by 2170
Abstract
Clay minerals are the signature of hydrothermal alterations related to fluid circulation in volcanic and crystalline rocks. In the French part of the Upper Rhine Graben, in the deep-seated granites, illitic minerals (illite and I/S mixed layers (ml)) are typical products of the [...] Read more.
Clay minerals are the signature of hydrothermal alterations related to fluid circulation in volcanic and crystalline rocks. In the French part of the Upper Rhine Graben, in the deep-seated granites, illitic minerals (illite and I/S mixed layers (ml)) are typical products of the structurally-controlled argillic alteration in the Paleozoic granitic basement. In the new Illkirch geothermal well, GIL-1, drill-cuttings were studied with various petrographic methods to determine the characteristics of illite in paleo- and present-permeable zones, and to compare the alteration mineralogy with that of geothermal Soultz-sous-Forêts and Rittershoffen sites. Alteration petrography, crystal structure as well as the chemical composition of the illitic minerals and the altered bulk rocks were performed all along the well. This complete characterization, combined with geophysical logs and structural results, highlighted that the illitic minerals at Illkirch, Soultz-sous-Forêts, and Rittershoffen are composed of illite and illite-rich illite-smectite mixed layers (I/S ml) (<10% smectite). Two mineralogical assemblages were distinguished: chlorite + illite resulting from the propylitic alteration after the emplacement of the granitic basement under temperatures higher than 350 °C, and illite + I/S ml + carbonates + quartz resulting from the argillic alteration due to fluid circulation in the fractures at temperatures between 130 and 160 °C. Fracture zones are characterized by the occurrence of illitic minerals (illite and I/S ml), and specifically, by higher quantities of I/S ml in present-day permeable zones than in paleo-permeable zones. A conceptual model of the fracture zones at the interface between the overlying sedimentary rocks and the granitic basement is proposed. The present-day permeability distribution is controlled by the fault and fracture network, which consists of sealed zones and unsealed zones. Fluid convection in the URG implies paleo and present fluids circulating in both fractured sedimentary and crystalline reservoirs. Such circulations develop illitic minerals that could be considered as exploration guides for future geothermal sites in the URG. At Illkirch, the repartition of the present-permeable fracture zones (KFZs) in the GIL-1 well indicates that the moderately argillically altered granite distally situated from the Eschau fault is more permeable than the intensely argillically altered granite close to the Eschau fault. Full article
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Review

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27 pages, 14435 KiB  
Review
Induced Polarization as a Tool to Assess Alteration in Geothermal Systems: A Review
by Andre Revil and Marceau Gresse
Minerals 2021, 11(9), 962; https://doi.org/10.3390/min11090962 - 02 Sep 2021
Cited by 12 | Viewed by 2779
Abstract
The mineral alteration patterns in high- to low-temperature geothermal fields affect the induced polarization (electrical conductivity and chargeability) properties of volcanic rocks. Indeed, these properties are sensitive to the cation exchange capacity and the porosity of the rock, which are both dependent on [...] Read more.
The mineral alteration patterns in high- to low-temperature geothermal fields affect the induced polarization (electrical conductivity and chargeability) properties of volcanic rocks. Indeed, these properties are sensitive to the cation exchange capacity and the porosity of the rock, which are both dependent on the alteration path, temperature, and depth of burial. Therefore induced polarization tomography appears as a powerful non-intrusive geophysical method to investigate alteration patterns in geothermal fields. Among clay minerals, the production of smectite through prograde reactions occurs progressively in volcanic rocks up to 220 °C. The presence of smectite dominates the induced polarization response of the volcanic rocks because of its very large cation exchange capacity. It follows that induced polarization can be used as a non-intrusive temperature proxy up to 220 °C for both active and inactive geothermal fields, recording the highest temperatures reached in the past. The influence of magnetite and pyrite, two semi-conductors, also has a strong influence regarding the induced polarization properties of volcanic rocks. Various field examples are discussed to show how induced polarization can be used to image volcanic conduits and smectite-rich clay caps in volcanic areas for both stratovolcanoes and shield volcanoes. Full article
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