Boiling and depth calculations in active and fossil hydrothermal systems: A comparative approach based on fluid inclusion case studies from Mexico

Cruz-Pérez, Miguel Á.; Canet, Carles; Franco, Sara; Camprubí, Antoni; Gonzáléz-Partida, Eduardo; Rajabi, Abdorrahman

doi:10.1016/j.oregeorev.2015.08.016

Cited by 11 publications

(4 citation statements)

References 43 publications

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“…The acid conditions are formed by the disproportionation of magmatic SO 2 and the presence of acids (e.g., HCl and HF, Aguilera et al, 2012), subsequent to magmatic vapours being absorbed by ground water . Here acid sulphate alteration occurs dominantly as a stratabound blanket that caps the system, generally with opal, cristobalite, kaolinite, alunite, sulphides and native sulphur association, such as shown in volcanic geothermal systems (Henley and Ellis, 1983;Hedenquist, 1991) and epithermal deposits (Ebert and Rye, 1997;Cruz-Pérez et al, 2016). Alunite may also form as a fumarole sublimate (Zimbelman et al, 2005).…”

Section: Discussionmentioning

confidence: 99%

Hydrothermal alteration, fumarolic deposits and fluids from Lastarria Volcanic Complex: A multidisciplinary study

Aguilera

Layana

Rodríguez-Díaz

et al. 2016

andgeo

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ABSTRACT.A multidisciplinary study that includes processing of Landsat ETM+ satellite images, chemistry of gas condensed, mineralogy and chemistry of fumarolic deposits, and fluid inclusion data from native sulphur deposits, has been carried out in the Lastarria Volcanic Complex (LVC) with the objective to determine the distribution and characteristics of hydrothermal alteration zones and to establish the relations between gas chemistry and fumarolic deposits. Satellite image processing shows the presence of four hydrothermal alteration zones, characterized by a mineral assemblage constituted mainly by clay minerals, alunite, iron oxides, and more subordinated ferrous minerals and goethite. Hydrothermal alteration zones present in the Lastarria sensu stricto volcano are directly related to the recent fumarolic activity. Geochemistry of fumarolic gas condensed, obtained from two fumaroles at temperatures between 328 and 320 °C, has allowed detecting 37 diverse elements corresponding to halogens, chalcophiles, siderophiles, alkali metals, alkali earth metals and Rare Earth Elements (REE), with concentrations that vary widely between 5,620 ppm (chlorine) and 0.01 ppm (Mo, Ag, Sn, Pb, Se, Mg and Cr). Logarithm of Enrichment Factor (log EF i ) for each element present values between 6.35 (iodine) and <1 (K, Na, Ca, Fe and Al). Those elements are originated primarily from a magmatic source, whereas at shallow level a hydrothermal source contributes typical rock-related elements, which are leached from the wall rock by a strong interaction with hyperacid fluids. Mostly of elements detected are transported to the surface in the fumarolic emissions as gaseous species, while very few elements (Mg, Ca and Al) are transported in silicate aerosols. A wide spectrum of minerals are present in the fumarolic deposits, which are constituted by sublimates and incrustations, and the main minerals phases are distributed in six mineral families, corresponding to sulphates, hydrated sulphates, sulphides, halides, carbonates, silicates and native element minerals. The sublimate/incrustation minerals are dominated by the presence of sulphate, sulphur, chlorine and diverse rock-related elements, which are formed by processes that include a. oxidation of gaseous phase; b. strong rock-fluid interaction; c. dissolution of silicate minerals and volcanic glass; d. gas-water interaction; e. deposition/precipitation of saline bearing minerals; f. oxidation of sublimates/incrustations to form secondary minerals and g. remobilization of sulphur deposits by meteoric water. Despite that sublimate/ incrustation minerals are dominated by rock-related elements, its chemistry shows high contents of high-volatile elements as As, Sb, Cd, among others. Fluid inclusions studies carried out in thin pseudobanded native sulphur from fumarolic deposits, by use of Raman and infrared spectroscopy combined with microthermometry analyses, provided evidence of H 2 O, CO 2 , H 2 S, SO 4 , COS bearing fluids, homogenization temperatures around 110 °C and salinities v...

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Section: Discussionmentioning

confidence: 99%

Hydrothermal alteration, fumarolic deposits and fluids from Lastarria Volcanic Complex: A multidisciplinary study

Aguilera

Layana

Rodríguez-Díaz

et al. 2016

andgeo

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“…The change of conditions with depth, and particularly the boiling and flashing of the hydrothermal fluids in the deeper levels, is consistent with the wider range of salinities recorded for this stage (Table 2, Figure 12). In a boiling scenario, the separation of a steam phase from the hydrothermal fluid is related to the fractionation of volatiles (e.g., CO 2 , H 2 S) and relative volumetric changes between the steam and fluid phases, therefore inducing changes in the physico-chemical characteristics of the residual hydrothermal fluids, such as a variation in their salinities [127][128][129]. Moreover, following [80], the combination of boiling a gas-rich fluid with subsequent dilution is characterized by a drop in Tm due to the loss of dissolved gas followed by a gentle Tm decrease with fluid inclusion homogenization temperatures (Th).…”

Section: Deep-seated Hydrothermal Fluidsmentioning

confidence: 99%

Hydrothermal Alteration in the Nevados de Chillán Geothermal System, Southern Andes: Multidisciplinary Analysis of a Fractured Reservoir

et al. 2023

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The interplay between a heat source, primary plus secondary permeability, and hydrothermal fluids makes geothermal systems a highly dynamic environment where evolving physico-chemical conditions are recorded in alteration mineralogy. A comprehensive characterization of hydrothermal alteration is therefore essential to decipher the major processes associated with geothermal system development. In this study, we defined the hydrothermal mineralogical evolution of the Nevados de Chillán Geothermal System (NChGS), located in the Southern Volcanic Zone (SVZ) of the central Andes, where the regional framework of the system is formed by a direct association with a currently active volcanic complex, a favorable structural control, and vertically inhibited fluid circulation. To characterize the secondary mineralogy present in the NChGS, we integrated optical petrography, Scanning Electron Microscopy (SEM) observations, X-ray Diffraction (XRD) analysis, and microthermometric measurements along a drill core with a depth of 1000 m at the Nieblas-1 well. These mineralogical approaches were combined with a structural field analysis to highlight the relevance of multidisciplinary study in understanding active geothermal systems. The results indicated that the evolution of the system involved four paragenetic stages, with the main processes in each phase being the heating, boiling, and mixing of fluids and re-equilibration to new physico-chemical conditions. Additionally, three hydrothermal zones were recognized: an upper argillic section, an intermediate sub-propylitic zone, and a deep propylitic domain. Sampled thermal springs are characterized by pH values of 2.4–5.9 and high SO4= concentrations (>290 ppm). These acid-sulfate steam-heated waters suggest the contribution of primary magmatic volatiles to the hydrothermal system. Alunite recorded in the alteration halos of veinlets presents at depths of 170–230 m denote the circulation of acidic fluids at these levels which were favored by reverse faults. These findings indicate that, at this depth range, the condensation of magmatic volatiles into shallow aquifers controls the recharge area of the superficial thermal manifestations. Conversely, deep-seated hydrothermal fluids correspond to near-neutral chloride fluids, with salinities ranging from 0.1 to 6.9 wt.% NaCl eq. The distribution of illite/smectite and chlorite/smectite mixed-layered minerals outline the presence of a significant clay cap, which, in this system, separates the steam-heated domain from the deep hydrothermal realm and restricts fluid circulation to existing permeable channels. Our mineralogical and structural study provides critical data for the interpretation of heat–fluid–rock interaction processes in the NChGS. The interplay between hydrothermal fluids and active faults is also discussed in the context of the complex of geological processes in active geothermal systems along the Chilean Southern Volcanic Zone.

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“…No pH estimates exist for the hydrothermal fluids forming the greisen and veins, but several observations suggest that it is unlikely that fluids avoided extensive rock buffering for up to two km in the thin pathways of the veins: (i) primary minerals in the wall rock adjacent to the veins are extensively altered [29]; (ii) the fluid inclusions were characterized by moderate to high salinity, Na-, Ca-, and K-chloridedominated compositions, and Na, Ca, Fe, or Si in the solid phases indicating that feldspar and possibly pyroxene, biotite, and magnetite contributed with chemical species throughout greisenization and veining; and (iii) at high fluid/rock ratios, greisen mineral assemblages are dominated by topaz-quartz [49], a feature not observed in the study area where the amount of topaz in the investigated greisen was very low. Boiling, or effervescence, is another process that may either decrease or increase fluid pH depending on the acidity of the gas phase released by unmixing [50,51]. The lack of a vapor phase in the primary fluid inclusions and the absence 13 Geofluids of a salinity increase with a decreasing homogenization temperature suggest that the formation depth of greisen and veins at 4-8 km [21] was too deep for boiling to occur.…”

Section: Physicochemical Evolution Of the Hydrothermal Systemmentioning

confidence: 99%

Fractionation of Rare Earth Elements in Greisen and Hydrothermal Veins Related to A-Type Magmatism

et al. 2019

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This study focuses on concentrations and fractionation of rare earth elements (REE) in a variety of minerals and bulk materials of hydrothermal greisen and vein mineralization in Paleoproterozoic monzodiorite to granodiorite related to the intrusion of Mesoproterozoic alkali- and fluorine-rich granite. The greisen consists of coarse-grained quartz, muscovite, and fluorite, whereas the veins mainly contain quartz, calcite, epidote, chlorite, and fluorite in order of abundance. A temporal and thus genetic link between the granite and the greisen/veins is established via high spatial resolution in situ Rb-Sr dating, supported by several other isotopic signatures (δ34S, 87Sr/86Sr, δ18O, and δ13C). Fluid-inclusion microthermometry reveals that multiple pulses of moderately to highly saline aqueous to carbonic solutions caused greisenization and vein formation at temperatures above 200–250°C and up to 430°C at the early hydrothermal stage in the veins. Low calculated ∑REE concentration for bulk vein (15 ppm) compared to greisen (75 ppm), country rocks (173–224 ppm), and the intruding granite (320 ppm) points to overall low REE levels in the hydrothermal fluids emanating from the granite. This is explained by efficient REE retention in the granite via incorporation in accessory phosphates, zircon, and fluorite and unfavorable conditions for REE partitioning in fluids at the magmatic and early hydrothermal stages. A noteworthy feature is substantial heavy REE (HREE) enrichment of calcite in the vein system, in contrast to the relatively flat patterns of greisen calcite. The REE fractionation of the vein calcite is explained mainly by fractional crystallization, where the initially precipitated epidote in the veins preferentially incorporates most of the light REE (LREE) pool, leaving a residual fluid enriched in the HREE from which calcite precipitated. Fluorite occurs throughout the system and displays decreasing REE concentrations from granite towards greisen and veins and different fractionation patterns among all these three materials. Taken together, these features confirm efficient REE retention in the early stages of the system and minor control of the REE uptake by mineral-specific partitioning. REE-fractionation patterns and fluid-inclusion data suggest that chloride complexation dominated REE transport during greisenization, whereas carbonate complexation contributed to the HREE enrichment in vein calcite.

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Boiling and depth calculations in active and fossil hydrothermal systems: A comparative approach based on fluid inclusion case studies from Mexico

Cited by 11 publications

References 43 publications

Hydrothermal alteration, fumarolic deposits and fluids from Lastarria Volcanic Complex: A multidisciplinary study

Hydrothermal alteration, fumarolic deposits and fluids from Lastarria Volcanic Complex: A multidisciplinary study

Hydrothermal Alteration in the Nevados de Chillán Geothermal System, Southern Andes: Multidisciplinary Analysis of a Fractured Reservoir

Fractionation of Rare Earth Elements in Greisen and Hydrothermal Veins Related to A-Type Magmatism

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