Journal articles on the topic 'Chlorite geothermometry'
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Walker, Jeffrey R. "Chlorite Polytype Geothermometry." Clays and Clay Minerals 41, no. 2 (1993): 260–67. http://dx.doi.org/10.1346/ccmn.1993.0410212.
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de Caritat, Patrice. "Chlorite Geothermometry: A Review." Clays and Clay Minerals 41, no. 2 (1993): 219–39. http://dx.doi.org/10.1346/ccmn.1993.0410210.
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Bourdelle, Franck. "Low-Temperature Chlorite Geothermometry and Related Recent Analytical Advances: A Review." Minerals 11, no. 2 (January 28, 2021): 130. http://dx.doi.org/10.3390/min11020130.
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Chlorite, a 2:1:1 phyllosilicate, has all the required attributes to form the basis of a geothermometer: this mineral is ubiquitous in metamorphic, diagenetic, and hydrothermal systems with a broad field of stability and a chemical composition partly dependent on temperature (T) and pressure (P) conditions. These properties led to the development of a multitude of chlorite thermometers, ranging from those based on empirical calibrations (linking T to AlIV content) to thermodynamic or semi-empirical models (linking T to chlorite + quartz + water equilibrium constant). This present study provides an overview of these geothermometers proposed in the literature for low-temperature chlorite (T < 350 °C), specifying the advantages and limitations of each method. Recent analytical developments that allow for circumventing or responding to certain criticisms regarding the low-temperature application of thermometers are also presented. The emphasis is on micrometric and nanometric analysis, highlighting chemical intracrystalline zoning—which can be considered as evidence of a succession of local equilibria justifying a thermometric approach—and mapping ferric iron content. New perspectives in terms of analysis (e.g., Mn redox in Mn-chlorite) and geothermometer (molecular solid-solution model, oxychlorite end-member) are also addressed.
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López-Munguira, A., F. Nieto, and D. Morata. "Chlorite composition and geothermometry: a comparative HRTEM/AEM-EMPA-XRD study of Cambrian basic lavas from the Ossa Morena Zone, SW Spain." Clay Minerals 37, no. 2 (June 2002): 267–81. http://dx.doi.org/10.1180/0009855023720033.
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AbstractChlorites from Cambrian basaltic vesicular lavas, characterized by relatively highXc (0.81-0.98), gave temperatures of formation of 285 to 350°C (Cathelineau's empirical geothermometer). Both theXcand temperature calculations gave results which were too high for the diagenetic conditions indicated by the interbedded shale mineralogy. The HRTEM and XRD studies indicate the absence of smectite layers in these chlorites; i.e. according to lattice images, the actual value ofXcis 1. The chlorite composition in these basaltic lavas must, therefore, be explained in relation to their whole-rock geochemistry, with which a good correlation has been found. The basaltic lavas are characterized by relatively high FeO/M ratios (3.28±1.66) and must be considered as an Fe-rich system, with similar chemical behaviour to pelitic rocks. In these cases, direct chlorite formation, without a previous smectite precursor, is a normal occurrence and theXccalculation and empirical geothermometric calculations are inadequate.
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PERRAKI, M., and E. MPOSKOS. "New constraints for the alpine HP metamorphism of the Ios basement, Cyclades, Greece." Bulletin of the Geological Society of Greece 34, no. 3 (January 1, 2001): 977. http://dx.doi.org/10.12681/bgsg.17130.
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The pre-Alpine basement of the Ios Island involves large Variscan granitoid bodies intruded into metasediments that had already been metamorphosed under upper amphibolite facies conditions, as it is indicated by residual migmatitic textures and deformed muscovite pegmatites. The Alpine HP-metamorphism, documented on various cycladic islands, has, also, affected the basement rocks of Ios. Pressures of '25 Kbar and temperatures of '540 °C, are estimated for the Alpine HP event, applying the chloritoid-chlorite and garnetclinopyroxene geothermometers, and the garnet-phengite-omphacite and garnet-rutile-quartz-sphene-clinozoisite geobarometers. Garnet-hornblende geothermometry yielded temperatures of '520 °C and garnet-chlorite geothermobarometry yielded temperatures of 450 °C at 15 Kbar. This suggests that, at least the first stages of decompression were accompanied by cooling, indicating a rapid exhumation, related to tectonic processes.
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Süssenberger, Annette, Susanne Theodora Schmidt, Florian H. Schmidt, and Manuel F. G. Weinkauf. "Reaction progress of clay minerals and carbonaceous matter in a contact metamorphic aureole (Torres del Paine intrusion, Chile)." European Journal of Mineralogy 32, no. 6 (December 9, 2020): 653–71. http://dx.doi.org/10.5194/ejm-32-653-2020.
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Abstract. This study reports on reaction processes in a transition zone from contact to regional metamorphism by using Raman spectroscopy on carbonaceous matter (RSCM), illite “crystallinity” (Kübler index, KI), chlorite geothermometry, and thermal modeling. The thermal effect due to the emplacement of the Torres del Paine intrusion (TPI, assembly time of ca. 150 kyr) had different consequences for inorganic and organic compounds of the host rock. The thermal alteration of the pre-intrusive regional metamorphosed host rock is documented by elevated RSCM temperatures, high-temperature chlorite generations, and the appearance of epidote and retrograde Fe-rich chlorite. Microprobe analysis on chlorite indicates incomplete re-equilibration as evidenced by various chlorite populations of individual contact metamorphic samples. This study indicates that the maturity of organic matter is the most reliable and unequivocal indicator on timescales of several thousand years to determine the lateral extension of the TPI contact aureole. Raman geothermometry reveals that the lateral extension of the contact-influenced zone expands up to a distance of 1.5 km and, thus, expands to ca. 1.1 km further out than the macroscopically mappable hornfels contact aureole. The best match between measured (Raman geothermometry) and calculated (thermal modeling) ΔTmax values (ΔT=54 ∘C) is achieved with a total intrusion assembly time of 150 kyr, a magmatic temperature of 800 ∘C, a two-batch model (batch repose time of 10 kyr) with five pulses per batch, short heating durations (3 kyr), and long pulse repose times (15 kyr).
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Jiang, Wei-Teh. "Chlorite Geothermometry?—Contamination and Apparent Octahedral Vacancies." Clays and Clay Minerals 42, no. 5 (1994): 593–605. http://dx.doi.org/10.1346/ccmn.1994.0420512.
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Esteban, J. J., J. Cuevas, and J. M. Tubía. "Geochemistry and origin of zircon in chlorite schists of the Ronda peridotites (Betic Cordilleras, southern Spain)." Lithosphere 11, no. 6 (November 4, 2019): 855–67. http://dx.doi.org/10.1130/l1088.1.
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Abstract This work deals with scarce chlorite schists scattered through the Ronda peridotites (Betic Cordilleras, Spain). These schists have unusually high zircon contents, which contrast with the usual lack of this mineral in ultramafic rocks. From field data and detailed petrographic, geochemical, and geothermometric studies, we focused on the origin of the zircon, a relevant issue for the interpretation of geochronological results. The chlorite schists appear as concordant sheets with granite dikes and as blackwall zones between dikes and serpentinized peridotites. As the intrusion age of the dikes and chlorite schist zircon crystallization (ca. 22 Ma) is slightly older than the age of serpentinization and related chlorite schist formation (ca. 19 Ma), we propose that the chlorite schists are tied to the intrusion of the granite dikes and the subsequent serpentinization of peridotites. Trace and rare earth elements alone are not indicative of the magmatic or hydrothermal origin of the zircon, but the combination of information about zircon morphology, melt inclusions, geothermometry, and the structural relationships between granite dikes and chlorite schists points to late magmatic melts for the zircon origin. We suggest that high-temperature melts saturated in F and Cl acted as Zr carriers under low-pH conditions. A change of the pH conditions, due to hydrothermal alkaline fluids incoming for the concomitant peridotite serpentinization, would have led to zircon crystallization and concentration at the apical zones of the dikes, and to rodingitization before the extensive observed chloritization.
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Pires, F. R. M., and L. C. Bertolino. "Estudo do metamorfismo nas formações proterozóicas no quadrilátero Ferrífero, MG." Anuário do Instituto de Geociências 14 (December 1, 1991): 1–9. http://dx.doi.org/10.11137/1991_0_1-9.
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The study of the metamorphism of Proterozoic units of the Quadrilátero Ferrífero is revisited in terms of the historical evolution and the application of the carbonate geothermometry method. Previous work indicates an eastward increase of the metamorphic grade and the relative distribuition of the chlorite, biotite, kyanite and staurolite zones. Oxygen isotope and carbonate geothermometry values corroborate previous investigations. Microprobe analysis of coexisting calcite and dolomite indicate attainment of exchange equilibrium for samples of Aguas Claras, Morro Agudo mines and Dom Bosco area. Temperatures of equilibrium obtained from calcite-dolomite pairs range from 283ºC to 547º.
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Maison, Tatiana, Sébastien Potel, Pierre Malié, Rafael Ferreiro Mählmann, Frank Chanier, Geoffroy Mahieux, and Julien Bailleul. "Low-grade evolution of clay minerals and organic matter in fault zones of the Hikurangi prism (New Zealand)." Clay Minerals 53, no. 4 (December 2018): 579–602. http://dx.doi.org/10.1180/clm.2018.46.
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ABSTRACTClay minerals and organic matter occur frequently in fault zones. Their structural characteristics and their textural evolution are driven by several formation processes: (1) reaction by metasomatism from circulating fluids; (2)in situevolution by diagenesis; and (3) neoformation due to deformation catalysis. Clay-mineral chemistry and precipitated solid organic matter may be used as indicators of fluid circulation in fault zones and to determine the maximum temperatures in these zones. In the present study, clay-mineral and organic-matter analyses of two major fault zones – the Adams-Tinui and Whakataki faults, Wairarapa, North Island, New Zealand – were investigated. The two faults analysed correspond to the soles of large imbricated thrust sheets formed during the onset of subduction beneath the North Island of New Zealand. The mineralogy of both fault zones is composed mainly of quartz, feldspars, calcite, chabazite and clay minerals such as illite-muscovite, kaolinite, chlorite and mixed-layer minerals such as chlorite-smectite and illite-smectite. The diagenesis and very-low-grade metamorphism of the sedimentary rock is determined by gradual changes of clay mineral ‘crystallinity’ (illite, chlorite, kaolinite), the use of a chlorite geothermometer and the reflectance of organic matter. It is concluded here that: (1) the established thermal grade is diagenesis; (2) tectonic strains affect the clay mineral ‘crystallinity’ in the fault zone; (3) there is a strong correlation between temperature determined by chlorite geothermometry and organic-matter reflectance; and (4) the duration and depth of burial as well as the pore-fluid chemistry are important factors affecting clay-mineral formation.
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Bourdelle, Franck, and Michel Cathelineau. "Low-temperature chlorite geothermometry: a graphical representation based on a T–R2+ –Si diagram." European Journal of Mineralogy 27, no. 5 (September 7, 2015): 617–26. http://dx.doi.org/10.1127/ejm/2015/0027-2467.
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Bozkaya, Ömer, and Hüseyin Yalçın. "Mineral Chemistry of Low-Temperature Phyllosilicates in Early Paleozoic Metaclastic Rocks, Eastern Tauride Belt, Türkiye." Minerals 12, no. 9 (August 28, 2022): 1088. http://dx.doi.org/10.3390/min12091088.
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The mineral chemistry of illite/mica and chlorites, together with the evaluation of textural data of low-temperature metaclastic rocks, plays an important role in determining their origin and metamorphic grade. This study aimed to investigate the chemical properties of phyllosilicates in early Paleozoic metaclastic rocks in the Eastern Tauride Belt, Türkiye. The textural (electron microscopy) and chemical (mineral chemistry analysis) analyses were performed on the samples representing different grades of metamorphism. The illites/micas and chlorites are observed as detrital (chlorite–mica stacks) and neoformation origin. Trioctahedral chlorites (chamosite) exhibit different chemistry for detrital and neoformed origin as well as the metamorphic grade. Tetrahedral Al and octahedral Fe + Mg increase, whereas octahedral Al decreases together with the increasing grade of metamorphism. The detrital chlorites have higher tetrahedral Al and Fe contents than their neoformed counterparts. Chlorite geothermometry data (detrital: 241–≥350 °C; neoformed: 201–268 °C) are compatible with the texture and illite Kübler index data. Illite/white-mica compositions display muscovite and Na-K mica. Tetrahedral Al and interlayer K + Na contents of illites/micas increase with metamorphic grade. Na-K mica and paragonite are observed as replacement-type developments within the detrital CMS. The obtained data indicate that phyllosilicate chemistry can be used effectively for determining the geological evolution of low-grade metamorphic sequences.
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Kordi Sykan, D., and SV Shahrokhi. "Mineral chemistry and geothermometry of chlorite in Zavarijan area (NE Broujerd-Iran)." Iranian Journal of Crystallography and Mineralogy 29, no. 1 (March 1, 2021): 3–18. http://dx.doi.org/10.52547/ijcm.29.1.3.
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Bobos, I., F. Noronha, and A. Mateus. "Fe-, Fe,Mn- and Fe,Mg-chlorite: a genetic linkage to W, (Cu,Mo) mineralization in the magmatic-hydrothermal system at Borralha, northern Portugal." Mineralogical Magazine 82, S1 (March 21, 2018): S259—S279. http://dx.doi.org/10.1180/minmag.2017.081.104.
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ABSTRACTA genetic linkage between W, (Cu, Mo)-mineralization and chlorite minerals, and the discrimination of different mineralization events in the magmatic-hydrothermal system of Borralha, northern Portugal, is discussed on the basis of textural relationships, crystal chemistry and stable isotopic data obtained from chlorite. Chlorite minerals were identified in assemblages with quartz, feldspars, tungstates and sulfides. X-ray diffraction studies of selected chlorite minerals shows a trioctahedral structural type. Electron probe micro-analyses identified four different compositions and associations: (1) Fe,Mn-chlorite with scheelite I; (2) Fe-chlorite with wolframite + scheelite II ± sulfide; (3) Fe,Mg-chlorite with molybdenite + bismuthinite; and (4) Mg,Fe-chlorite with chalcopyrite. The composition of Fe-chlorite (Al3.01Fe3+0.25Fe2+7.95Mn0.26Mg0.19)11.66(Si5.44Al2.56)8O20(OH)8 corresponds to daphnite and Fe,Mn-chlorite (Al2.69Fe3+0.02 Fe2+7.54Mn1.08Mg0.62)11.89(Si5.31Al2.68)4O20(OH)8 to a mixed composition between daphnite and amesite. The Fe,Mg-chlorite (Al2.89Fe3+0.24Fe2+6.42Mn0.21Mg2.08)11.84 (Si5.31Al2.79)8F0.31O20(OH)8 corresponds to ripidolite and Mg,Fe-chlorite (Al2.63Fe3+0.37Fe2+1.72Mn0.01Mg6.40Ca0.26)11.39(Si6.02Al1.98)8O20(OH)8 to pychnochlorite.Chlorite geothermometry estimates a temperature for Fe,Mn-chlorite (scheelite I) from 400°C to 500°C, for Fe-chlorite (Mn-rich wolframite + scheelite II ± sulfide) from 250 to 350°C, for Fe,Mg-chlorite (Mo-mineralization) from 200°C to 250°C and for Mg,Fe-chlorite at ~150°C. Oxygen isotopes (V-SMOW) yielded values of +3.8 (1σ) (Fe-chlorite), +6.91 (1σ) (Fe,Mn-chlorite) and +1.5 (1σ) (Fe,Mg-chlorite). The calculated δ18OF of Fe- and Fe,Mg-chlorite is ~+3.75 (1σ) and +1.45 (1σ) for the mineralizing fluid, whereas for Fe,Mn-chlorite it is +8.17 (1σ). The δ18O data obtained from quartz in W- and Mo-mineralization yielded values of +12.6 and +11.4 (1σ), whereas for adularia δ18O is about +10 (1σ). These estimates allow us to conclude that the Fe,Mn-chlorite crystallized from a magmatic-hydrothermal fluid, whereas the Fe- and Fe,Mg-chlorite quartz and adularia resulted from a mixed contribution between meteoric and magmatic-hydrothermal fluid.
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Plotinskaya, O. Yu. "Mineralogy of precious metals in ores of the Yubileinoe porphyry gold deposit (Kazakhstan)." МИНЕРАЛОГИЯ (MINERALOGY), no. 3 (October 28, 2020): 44–53. http://dx.doi.org/10.35597/2313-545x-2020-6-3-4.
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Gold and silver mineralogy is studied in ores of the Yubileinoe porphyry gold deposit (Kazakhstan). Native gold is the major gold mineral. Its fneness varies from 970‰ in magnetite-hematite assemblage to 733–860‰ in pyrite-chalcopyrite assemblage. Silver occurs as admixture in native gold and, occasionally, as silver telluride. Native gold is associated with bi and Pb minerals: rucklidgeite, galenaclaustalite, and tetradymite-kawazulite. According to chlorite geothermometry, the Au, Ag and bi minerals precipitated at temperatures of 250-230 °С. These features are typical of the porphyry gold deposits worldwide. Figures 5. Tables 3. References 17.
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Wang, Yongjian, Honghai Fan, Yaqing Pang, and Wei Xiao. "Geochemical Characteristics of Chlorite in Xiangshan Uranium Ore Field, South China and Its Exploration Implication." Minerals 12, no. 6 (May 30, 2022): 693. http://dx.doi.org/10.3390/min12060693.
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Chlorite is one of the most important hydrothermal minerals in many hydrothermal uranium deposits worldwide and is commonly closely associated with the uranium mineralization. Trace elements in chlorite have been extensively applied to fingerprinting the hydrothermal fluid evolution and indicating the concealed ore bodies in porphyry Cu (-Au) deposits and skarn-related Pb-Zn deposits. However, this approach was rarely attempted on hydrothermal uranium deposits to date. Xiangshan uranium ore field, located in the southeast part of Gan-Hang Metallogenic (or Volcanic) Belt (GHMB), is the largest volcanic-related ore field in the whole country. In this study, the focus was placed on the petrographic characteristics and trace elements in hydrothermal chlorite from two typical deposits (Zoujiashan and Yunji) at Xiangshan. Four types of chlorites were identified, i.e., Chl1-Y and Chl2 from Yunji deposit, and Chl1-Z and Chl3 from Zoujiashan deposit. The pre-ore Chl1-Y and Chl1-Z are formed through replacing the original magmatic biotite. Chl2 and Chl3 occur as veinlets or disseminated, and are closely associated with early-ore U mineralization and main-ore U mineralization, respectively. All the four types of chlorites are typically trioctahedral chlorite. Vein-type/disseminated Chl2 and Chl3 in ore veins were precipitated directly from the hydrothermal fluids through dissolution-migration-precipitation mechanism, whereas the replacement-type chlorite was formed by the dissolution–crystallization mechanism. Empirical geothermometry indicates that the chlorite from Yunji and Zoujiashan were crystallized at 179~277 °C, indicating a mesothermal-epithermal precipitation environment. EPMA and LA-ICP-MS results show that the replacement-type chlorite has relatively consistent compositions at Yunji and Zoujiashan. Both Chl2 and Chl3 are enriched in U, Th but depleted in Mn and Ti. Compared with the Chl2 related to early-ore U mineralization, Chl3 that formed at main-ore stage has higher concentrations of Fe, U, Th, REEs, Mn and Ti, as well as higer Fe/(Fe + Mg) ratios. Such compositional differences between Chl2 and Chl3 are mainly attributed to the formation temperatures and fluid compositions/natures. Combined with petrology and chemical compositions of different types of chlorite, we propose that the presence of vein-type/disseminated chlorite with high U and Fe/(Fe + Mg) ratio but relatively low Mn, Ti and Pb contents can be regarded as an effective vector toward the most economic (high U grade) mineralized zone, whereas the occurrence of Chl2 is likely to indicate the subeconomic U mineralization and less potential exploration for uranium at depth.
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Timpa, Sean, Kathryn M. Gillis, and Dante Canil. "Accretion-related metamorphism of the Metchosin Igneous Complex, southern Vancouver Island, British Columbia." Canadian Journal of Earth Sciences 42, no. 8 (August 1, 2005): 1467–79. http://dx.doi.org/10.1139/e05-043.
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The metamorphic history of the volcanic sequence of the Metchosin Igneous Complex (MIC), an Eocene ophiolite exposed on southern Vancouver Island, British Columbia, Canada, was studied to examine the roles of seafloor and accretion-related processes. Metamorphic facies in the volcanics vary from prehniteactinolite assemblages in the east to greenschist and amphibolite assemblages in the west. In the east, metamorphism is typified by chlorite ± prehnite ± epidote ± actinolite assemblages that fill vesicles and replace interstitial material; plagioclase is variably albitized, and clinopyroxene is relatively fresh. In the west, the common groundmass assemblage is amphibole + epidote ± chlorite. These assemblages and chlorite geothermometry show a regional eastwest gradient of ∼510 °C/km that is oblique to the volcanic stratigraphy. The regional metamorphic facies distribution for the MIC volcanics is not consistent with seafloor hydrothermal metamorphism documented for ocean crust from mid-ocean ridges, ocean islands, or island arcs. We speculate that underthrusting of the MIC beneath the Pacific Rim Terrane led to the regional metamorphism of the MIC, and that the change in metamorphic grade from east to west results from regional tilting of the complex, perhaps by orographic effects, during or after accretion.
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Breheny, C., K. R. Moore, A. Costanzo, and M. Feely. "Reconstruction of an Ordovician seafloor volcanohydrothermal system: a case study from the Copper Coast, southeastern Ireland using field, geochemical and fluid inclusion data." Mineralogical Magazine 80, no. 1 (February 2016): 157–74. http://dx.doi.org/10.1180/minmag.2015.079.7.09.
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AbstractVolcanic rocks in south County Waterford include flow-top hyaloclastite, pillow lavas and peperite, which are formed typically by sub-aqueous eruption or intrusion into unconsolidated sediment. Element mobility in wet sediment during emplacement of volcanic intrusions was reconstructed on a variety of spatial scales using bulk-rock and mineral analysis. Magma-sediment and magma-water interactions enhanced hydrothermal alteration. The chemistry of chlorite was a function of mixing between an Fe-rich magmatic fluid and a Mg-rich meteoric fluid. Chlorite geothermometry yields temperatures of formation between 230 and 388°C compatible with other metamorphic indicators. Fluid inclusion microthermometric data from genetically-related mineralized quartz veins reveal a hydrothermal vein mineralization event that occurred at lower temperatures during the end stage of volcanic activity. A convection driven mixing trend reflects the trapping of co-existing brine with entrained seawater concomitant with, the late stages of emplacement of the Bunmahon Volcano intrusions.
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Beaufort, D., C. Rigault, S. Billon, V. Billault, A. Inoue, S. Inoue, and P. Patrier. "Chlorite and chloritization processes through mixed-layer mineral series in low-temperature geological systems – a review." Clay Minerals 50, no. 4 (September 2015): 497–523. http://dx.doi.org/10.1180/claymin.2015.050.4.06.
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AbstractThis present study provides an overview of the clay-mineral reactions involved in the chloritization process in a mixed-layer mineral series, and focuses on the properties of the resulting lowtemperature chlorites (formed at <220°C) in diagenetic and hydrothermal systems. According to the literature, most chlorite species occurring in low-temperature geological systems are derived fromspecific clay precursors except for direct precipitates from solution in veins. In addition, three main types of clay-mineral series have been associated with these chloritization processes: saponite-to-chlorite, berthierineto- chlorite and kaolinite-to-sudoite reactions. The conversion of saponite to chlorite results in the most common sequence of trioctahedral clay minerals related to the occurrence of Mg-Fe trioctahedral chlorite in a wide variety of hydrothermal and diagenetic to very low-grade metamorphism environments. Two models were proposed in the literature to describe the saponite-to-chlorite conversion through corrensite. The first model is a continuous transition model based on solid-state transformation (SST) mechanisms and is valid in rock-dominated systems (closed micro-systems with very low fluid-rock ratios). The second model is a stepwise transition model based on dissolution-crystallization mechanisms (DC) and is efficient in fluid-dominated systems (open systems with high fluid-rock ratio). The berthierine to Fechlorite transition results in a sequence of trioctahedral phases which are related to chloritization processes in iron-rich and reducing environments. This transformation is a cell-preserved phase transition dominated by a SST mechanismthat operates simultaneously in different domains of the parental mineral and may be considered as a polymorphic mineral reaction. Finally, the conversion of kaolinite to sudoite (Al-Mg ditrioctahedral chlorite) has not been documented like the other two aforementioned conversion series. Despite the scarcity of detailed investigations, the conversion of kaolinite to sudoite through tosudite is considered a stepwise mineral reaction that is dominated by a DC mechanism. From a compilation of literature data, it appears that several parameters of hydrothermal and diagenetic chlorites differ, including the minimal temperature, the textural and structural characteristics and the extents of compositional fields. In hydrothermal systems, discrete chlorite occurs at a minimal temperature near 200°C, regardless of its chemical composition. In diagenetic systems, discrete chlorite occurs at minimal temperatures that vary according to its crystal chemistry (100–120°C for Mg-chlorite as opposed to 40–120°C for Fe chlorite). The strong discrepancy between the lowest temperature at which Mg- and Fe-chlorite form in buried sediments and in geothermal systems should result from drastically different heating rates, heat-flow conditions and tectonism between basins at passivemargins and geothermal systems at active margins. The morphology, structure and compositional fields of the diagenetic Fe-rich chlorite may have been inherited from those of the berthierine precursor. All of the chlorite species formed through theDC mechanism have good geothermometry potential. However, the SST mechanism in which berthierine is transformed into chlorite could have unexplored consequences regarding the use of the chemistry (including stable isotope composition) of diagenetic Fe-chlorite for reconstructing the burial history of sediments. Further investigations regarding the formationmechanisms of mixed-layerminerals are required to provide us with insight to understand the chloritization process in low-temperature geological systems.
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Inoue, Atsuyuki, Kyohei Kurokawa, and Tamao Hatta. "Application of Chlorite Geothermometry to Hydrothermal Alteration in Toyoha Geothermal System, Southwestern Hokkaido, Japan." Resource Geology 60, no. 1 (March 2010): 52–70. http://dx.doi.org/10.1111/j.1751-3928.2010.00114.x.
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Grambling, Jeffrey A. "Internally-consistent geothermometry and H2O barometry in metamorphic rocks: The example garnet-chlorite-quartz." Contributions to Mineralogy and Petrology 105, no. 6 (November 1990): 617–28. http://dx.doi.org/10.1007/bf00306528.
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Scheepers, R., R. D. O'Brien, and A. E. Schoch. "An occurrence of bavenite in the Cape Granite Suite, southwestern Cape Province, South Africa, and its implication on the formation of the host pegmatite." South African Journal of Geology 120, no. 2 (June 1, 2017): 223–30. http://dx.doi.org/10.25131/gssajg.120.2.223.
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Abstract Bavenite, (Ca4[(Al,Be)4(Si9(O,OH)26-n)](OH)2+n), is present in a pegmatite of the Paarl Pluton, a metaluminous I-type granite of Late Precambrian age. We are not aware of any other previous description of a beryllium mineral occurrence in the Cape Granite Suite. The pegmatite consists essentially of quartz and microcline microperthite together with albite, calcite and fluorite. A hydrothermal alteration assemblage of epidote, chlorite and bavenite occurs in vugs and veins within the pegmatite. Stilbite, which is stable below 170ºC, is also present, but not texturally related to the alteration assemblage. Microthermometric analyses and mineral chemistry of associated minerals elucidate the conditions of formation for the bavenite. According to primary fluid inclusions in the cores of euhedral quartz, the minimum temperature of crystallization of the pegmatite is 450ºC. Homogenization temperatures of later fluids indicate a minimum temperature of 210ºC for the main hydrothermal event. Chlorite geothermometry yields crystallization temperatures around 320ºC. The bavenite formed between 210ºC and 320ºC, at a pressure of less than 2 kbar.
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Wilkinson, Jamie J., Michael J. Baker, David R. Cooke, and Clara C. Wilkinson. "Exploration Targeting in Porphyry Cu Systems Using Propylitic Mineral Chemistry: A Case Study of the El Teniente Deposit, Chile." Economic Geology 115, no. 4 (June 1, 2020): 771–91. http://dx.doi.org/10.5382/econgeo.4738.
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Abstract The mineral chemistry of epidote and chlorite from the propylitic halo at El Teniente, in samples collected at distances up to 6.6 km from the deposit center, was determined by microprobe and laser ablation-inductively coupled plasma-mass spectrometry. Results show that both minerals systematically incorporated a range of trace elements that define a much larger footprint to the system than is easily recognized using conventional means such as whole-rock geochemistry. Apart from Fe and Mg in chlorite, there is no significant control of mineral chemistry by bulk-rock composition. For chlorite, geothermometry temperatures and Ti and V concentrations are high proximal, whereas Li, As, Co, Sr, Ca, and Y are low proximal and elevated in distal positions. Ratios of these elements define gradients toward ore varying over three to five orders of magnitude. The proximal-high Ti content is thought to reflect crystallization temperature, whereas proximal-low signatures are believed to characterize elements that are relatively fluid mobile in the inner parts of the propylitic halo in the presence of mildly alkaline to mildly acidic and oxidized fluids so that they are not incorporated into crystallizing chlorite, despite being generally compatible within the mineral structure. These elements begin to substitute into chlorite in the distal parts of the propylitic halo where fluids are largely rock buffered in terms of major element chemistry. In epidote, As defines a broad proximal low and is generally elevated at distances of at least 3 km from the edge of the ore shell. Zinc, La, Yb, Y, and Zr in epidote, among others, appear to define a geochemical shoulder that surrounds the deposit. These patterns are broadly similar to those observed in previous work at Batu Hijau and in the Baguio district, suggesting that these minerals behave consistently in porphyry systems and can therefore provide useful exploration tools within propylitic green rocks.
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González-Esvertit, Eloy, Àngels Canals, Josep Maria Casas, and Fernando Nieto. "Insights into the structural evolution of the pre-Variscan rocks of the Eastern Pyrenees from La Molina quartz veins; constraints on chlorite and fluid inclusion thermometry." Geologica Acta 18 (November 26, 2020): 1—XXIV. http://dx.doi.org/10.1344/geologicaacta2020.18.18.
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Quartz veins hosted in the infra and overlying series to the (Sardic) Upper Ordovician Unconformity provide new insights into the structural and thermal evolution of the pre-Variscan rocks of the Eastern Pyrenees. In the La Molina area (Canigó massif), two generations of metric quartz veins (V1 and V2) are distinguished by their distribution patterns and their relationships to the deformational macro, meso, and microstructures. P-T formation conditions are obtained by combining chlorite geothermometry and fluid inclusion microthermometry data. Discrepancy on formation temperature for chlorites located at different positions within the veins are discussed, concluding that veins grew in a low fluid/rock ratio regime. V1 veins can be related to the Late Ordovician syn-sedimentary faulting episode as revealed by their distribution patterns, formation mechanisms, and fluid-rock interactions. We propose an Alpine age for the V2 veins, based on their structure and the emplacement conditions of 318 ± 12°C and 2.4 ± 0.2kbar, with an estimated geothermal gradient of 34°C∙km-1 and a burial depth of ca. 9km. Results obtained here are compared with other quartz veins spread throughout the Paleozoic basement of the Eastern Pyrenees.
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TAGHIPOUR, SEDIGHEH, MAHMOUD KHALILI, MOHAMMAD ALI MACKIZADEH, ALI KANANIAN, and BATOUL TAGHIPOUR. "Mineralogy, geochemistry and petrogenesis of igneous inclusions within three inactive diapirs, Zagros belt, Shahre-kord, Iran." Geological Magazine 150, no. 1 (July 5, 2012): 72–88. http://dx.doi.org/10.1017/s0016756812000301.
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AbstractThe Kaj-Rostam Abad, Dashtak and Doab diapirs are part of the Precambrian–Cambrian Hormuz series that are rich in igneous inclusions concentrated by dissolution of diapiric salt. They are situated in the Iran–Pakistan salt range and commonly associated with inclusions of basalt, trachyte, andesite, micro-gabbro, gypsum and anhydrite, with lesser amounts of carbonate rocks. The mineral assemblage in these inclusions developed in three stages: (I) magmatic stage (diopside, Ti-augite, kaersutite, plagioclase, apatite, biotite and opaque minerals), (II) late magmatic stage (biotite, quartz, chlorite, albite, calcite, titanite, epidote, actinolite and opaque minerals) and (III) vein mineralization (quartz, chlorite, albite, calcite, garnet, epidote, opaque minerals and actinolite). Clinopyroxene is diopside to Ti-augite. Actinolite, kaersutite, albite and pycnochlorite are constituents of the metasomatic rocks of the area. Chlorite geothermometry yielded a temperature of 330–500 °C for chlorite formation. Clinopyroxene thermobarometry ranges from 960 ≤ T ≤ 1440 °C and 1 ≤ P ≤ 10 kbar. The presence of halite-bearing fluid inclusions in hydrothermal quartz veins with homogenization temperatures between 320 and 350 °C points to strong evidence of hydrothermal events. The salinity of these fluids is 39.8–42.7 wt% NaCl. δ18O data on hydrothermal quartz veins range from 14.89 to 22.09 ‰ (SMOW), indicating that the studied samples were affected by fluids originated from sedimentary-evaporitic rocks. Meteoric water that penetrated the evaporitic rocks likely mixed with late magmatic fluids while subjected to magmatic heat, when buried to depths of several kilometres by the Phanerozoic cover sequence. Whole-rock geochemistry data for the studied rocks emphasize their alkaline to sub-alkaline affinities, in a transitional magmatic series.
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Lalonde, Erik, and Georges Beaudoin. "Petrochemistry, hydrothermal alteration, mineralogy, and sulfur isotope geochemistry of the Turgeon Cu–Zn volcanogenic massive sulfide deposit, northern New Brunswick, Canada." Canadian Journal of Earth Sciences 52, no. 4 (April 2015): 215–34. http://dx.doi.org/10.1139/cjes-2014-0093.
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The Turgeon deposit is a mafic-type, Cu–Zn volcanogenic massive sulfide (VMS) deposit. It is hosted by Middle Ordovician pillow basalts of the Devereaux Formation of the Fournier Group within the Elmtree-Belledune inlier, near the Bathurst Mining Camp (BMC) in northern New Brunswick, Canada. The Turgeon deposit consists of two Cu–Zn massive sulfide lenses (“100m Zn”, “48-49”) composed of pyrite, chalcopyrite, pyrrhotite, and sphalerite, which are underlain by chalcopyrite–pyrite stockwork veins. Pyrite is overprinted and replaced by chalcopyrite in the stockwork and vent complex sulfide facies, where both minerals are enriched in Se and Co relative to pyrite and chalcopyrite in the massive pyrite and breccia sulfide facies. In, Se, and Co display a positive covariation with Cu, whereas Zn displays a positive covariation with Cd. Trace element geochemistry indicates that the host rocks are primarily tholeiitic basalts and andesites that have signatures between that of mid-ocean ridge basalt and island-arc tholeiite. The hanging wall rhyolite plots as an ocean ridge rhyolite and is geochemically similar to VMS-bearing FIIIa-type rhyolites. Hydrothermal alteration mineral assemblages in the footwall basalts proximal to mineralization are dominantly chlorite ± quartz in the stockwork zone, which is characterized by compositional gains in Fe and Mg and losses in Na and Ca. The chlorite-altered basalts and andesites have undergone up to 35% mass loss. Stockwork chlorite is an Fe-rich chamosite, whereas chlorite in the massive sulfides is a Mg-rich clinochlore. Chlorite geothermometry yields temperatures of 329–361 °C for chamosite and 246–286 °C for clinochlore. Sulfides at Turgeon have an average δ34SCDT of +6.9‰ (range: +5.8‰ to +10‰), indicating that sulfur was mostly derived from thermochemical reduction of Ordovician seawater sulfate. The Turgeon VMS deposit differs from those of the BMC, which is a reflection of their different tectonic settings; but it is similar to other mafic-type VMS deposits, such as the Betts Cove, Tilt Cove, and Rambler VMS deposits in Newfoundland, Canada.
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Chinchilla, Darío, Xabier Arroyo, Raúl Merinero, Rubén Piña, Fernando Nieto, Lorena Ortega, and Rosario Lunar. "Chlorite geothermometry applied to massive and oscillatory-zoned radiated Mn-rich chlorites in the Patricia Zn-Pb-Ag epithermal deposit (NE, Chile)." Applied Clay Science 134 (December 2016): 210–20. http://dx.doi.org/10.1016/j.clay.2016.10.013.
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Pacey, Adam, Jamie J. Wilkinson, Adrian J. Boyce, and Ian L. Millar. "Magmatic Fluids Implicated in the Formation of Propylitic Alteration: Oxygen, Hydrogen, and Strontium Isotope Constraints from the Northparkes Porphyry Cu-Au District, New South Wales, Australia." Economic Geology 115, no. 4 (June 1, 2020): 729–48. http://dx.doi.org/10.5382/econgeo.4732.
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Abstract In porphyry ore deposit models, the propylitic alteration facies is widely interpreted to be caused by convective circulation of meteoric waters. However, recent field-based and geochemical data suggest that magmatic-derived fluids are likely to contribute to development of the propylitic assemblage. In order to test this hypothesis, we determined the oxygen and hydrogen isotope compositions of propylitic mineral separates (epidote, chlorite, and quartz), selected potassic mineral separates (quartz and magnetite), and quartz-hosted fluid inclusions from around the E48 and E26 deposits in the Northparkes porphyry Cu-Au district, New South Wales, Australia. In addition, the strontium isotope composition of epidote was determined to test for the potential contribution of seawater in the Northparkes system given the postulated island-arc setting and submarine character of some country rocks. Oxygen isotope geothermometry calculations indicate potassic alteration occurred between ~600° and 700°C in magmatic/mineralized centers, persisting to ~450°C upon lateral transition into propylitic alteration. Across the propylitic facies, temperature progressively decreased outward to <250°C. These temperature estimates and additional data from chlorite geothermometry were utilized to calculate the oxygen and hydrogen isotope composition of the fluid in equilibrium with the sampled minerals. Results show that propylitic fluids spanned a range of compositions with δ18O between 0.5 and 3.7‰ and δD between –49 and –17‰. Comparison of these results with the modeled compositions of meteoric and/or magmatic fluids during their evolution and isotopic exchange with local country rocks shows that a magmatic fluid component must exist across the propylitic halo during its formation. Strontium isotope data from propylitic epidote provide initial (based on formation at ~450 Ma) 87Sr/86Sr values in the range of 0.704099 to 0.704354, ruling out the presence of seawater as a second fluid in the system. Although we cannot exclude magmatic-meteoric mixing, especially toward the fringes of the system, our results support a model in which magmatic-derived fluid is the primary driver of propylitic alteration as it undergoes cooling and chemical equilibration during outward infiltration into country rocks. This is consistent with chemical mass transfer calculations for Northparkes and published chemical-thermodynamic models that only require a magmatic fluid for the production of propylitic assemblages. In view of this and supporting data from other deposits, we suggest that magmatic fluids are essential drivers of propylitic alteration in porphyry systems.
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Voudouris, P., S. Constantinidou, M. Kati, C. Mavrogonatos, C. Kanellopoulos, and E. Volioti. "Genesis of alpinotype fissure minerals from Thasos Island, Northern Greece - Mineralogy, mineral chemistry and crystallizing environment." Bulletin of the Geological Society of Greece 47, no. 1 (September 5, 2013): 468. http://dx.doi.org/10.12681/bgsg.11024.
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Alpinotype fissure-minerals in Thasos Island are hosted in gneisses, amphibolites, Mn-rich schists and calc-silicate layers, and marbles of the Carboniferous-Permian Pangeon Unit, which represents the lower tectonostratigraphic unit of the southern Rhodope metamorphic core complex. Alpinotype fissures crosscut metamorphic fabrics and are closely related to the exhumation processes of the core complex during the Oligocene-Miocene. Most mineralized fissures occur close to a major detachment fault, which separates gneisses from marbles and amphibolites. The mineralogy of the alpinotype fissures is closely related to the host rocks: amphibolite-hosted fissures include adularia, albite, quartz, titanite, apatite, actinolite, chlorite, calcite, hematite and rutile. Fissures in para- and orthogneisses- and in metapegmatites are characterized by smoky and clear quartz, adularia, muscovite and hematite. Fissures within spessartite-piemontite schists contain quartz, chlorite, spessartite, hematite, rutile, albite, epidote and traces of zircon. Finally fissures in calc-silicate layers include Mn-grossular, quartz and Mn-clinozoisite. Hydrothermal alteration halos surrounding the fissures may suggest leaching of the wall rocks as a potential mechanism for mineral deposition. Scepter quartz crystals consist of a lower Tessinhabit crystal and several generations of upper prismatic quartz crystals, suggesting several stages of crystallization and changing P-T-x conditions with time. Chlorite geothermometry indicates temperatures of formation in the range between 286 and 366 °C. Tessin habit quartz was deposited from CO2-bearing fluids, probably at the transition from a compressional to an extensional tectonic regime and was later dissolved by meteoric water dominated fluids resulting in the formation of quartz scepters. Oxidizing conditions are indicated by the widespread occurrence of hematite in the mineralization. The studied area represents a unique mineralogical geotope. Its geological-mineralogical heritage should be protected through establishment of a mineralogical-petrological geopark that will also promote sustainable development of the area.
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Xie, Xiaogang, Gary R. Byerly, and Ray E. Ferrell Jr. "IIb trioctahedral chlorite from the Barberton greenstone belt: crystal structure and rock composition constraints with implications to geothermometry." Contributions to Mineralogy and Petrology 126, no. 3 (January 23, 1997): 275–91. http://dx.doi.org/10.1007/s004100050250.
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Hidayatullah, Muhammad Shofi, Agus Didit Haryanto, Johanes Hutabarat, and Ryan Hidayat. "etermination of Geothermal Reservoir Zone of Sorik Marapi, Mandailing Natal, North Sumatra." Indonesian Association of Geologists Journal 1, no. 1 (March 31, 2021): 13–24. http://dx.doi.org/10.51835/iagij.2021.1.1.24.
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The Sorik Marapi Geothermal Power (SMGP) Field is located in Mandailing Natal (350 km to the southeast from Medan), North Sumatra. This study needed alteration mineral data validation with fluid geochemical characteristics from surface manifestations, and production wells were determined the geothermal reservoir zone. Therefore geothermometer and geoindicator calculations were used. Laboratory tests were carried out on 38 surface manifestations and 11 cutting samples of exploration well. Manifestations in this area include hot springs, fumaroles, and steaming ground. Alteration minerals found in the study area are anhydrite, epidote, calcite,chlorite, muscovite, pyrophyllite, and zeolite. The alteration zone is located in the zeolite zone, the epidote zone,and the anhydrite-sericite zone. Geochemical manifestations of surface and production wells containing chloride water, sulfate water, sulfate-chloride water, and bicarbonate water. The estimated reservoir temperature of SH-01 well shows temperatures ranging from 240–280˚C, SH-02 well shows temperatures of 249.89–302.92˚C, SH-03 well show temperatures of 231.09–280˚C. The mineral geothermometer calculation, which is correlated with the geochemical fluid geothermometer, shows valid results. This is evident from the estimated reservoir temperatures of the two geothermometers.
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López de Azarevich, Vanina, Paolo Fulignati, Anna Gioncada, and Miguel Azarevich. "Rare element minerals’ assemblage in El Quemado pegmatites (Argentina): insights for pegmatite melt evolution from gahnite, columbite-group minerals and tourmaline chemistry and implications for minerogenesis." Mineralogy and Petrology 115, no. 5 (May 19, 2021): 497–518. http://dx.doi.org/10.1007/s00710-021-00752-0.
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AbstractThe pegmatite district of El Quemado (NW Pampean Ranges, NW Argentina) hosts several Ordovician pegmatite bodies of the LCT (Li, Cs, Ta) type. We present paragenetic assemblages for a set of samples from two of the El Quemado pegmatite groups, Santa Elena and Tres Tetas, and mineral chemistry analyses for gahnite, columbite-group minerals, tourmaline, micas, albite, microcline, and discuss the relation between their major element composition and the degree of evolution of pegmatite melts. The chemical composition of rare element minerals allows recognizing an evolutive trend reaching highly differentiated compositions, with complex paragenetic assemblages including Li-, Zr-, U-, Zn-, P-, Mn- and Ta-bearing minerals. The temperature of crystallization during the magmatic phase was below 400 °C. Non-pervasive hydrothermal alteration, testified by a moderate presence of phyllosilicates, affected the pegmatite bodies. Chlorite geothermometry indicates that the circulation of post-magmatic hydrothermal fluids occurred at a temperature ranging between 200 °C and 250 °C. The mineralogical features recognized in the El Quemado pegmatite rocks have implications for the metallogenesis of the region, suggesting that the pegmatites potentially contributed to the genesis of Ta-Nb oxide placer mineralizations.
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Visser, Diederik, and Antony Senior. "Mg-rich dumortierite in cordierite-orthoamphibole-bearing rocks from the high-grade Bamble Sector, south Norway." Mineralogical Magazine 55, no. 381 (December 1991): 563–77. http://dx.doi.org/10.1180/minmag.1991.055.381.09.
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AbstractDumortierite is described from several occurrences of cordierite-orthoamphibole-bearing rocks in the upper-amphibolite facies area of the Bamble Sector, south Norway. Dumortierite occurs with chlorite, muscovite and quartz in late M4 alteration zones or aggregates after M3, peak-metamorphic cordierite and garnet and early M4 vein-cordierite, and intergrown with or replacing orthoamphibole. Late M4P-T conditions, which are interpreted as conditions of dumortierite formation, are estimated from the associated late M4 kyanite-andalusite-chlorite-quartz assemblage and Mg-Fe exchange geothermometry to be 500 ± 50 °C and 3–4 kbar. Retrogression of M3 mineral assemblages is initiated by influx of fluids with XCO2 of 0.3–0.4 during early M4 followed by more water-rich fluids during late M4. Late M4 fluids may show local variations in alkalis and boron. The dumortierites are the most Mg-rich (2.23–3.42 wt. % MgO) ever reported, and contain 0.00–2.05 wt.% TiO2, 0.00–1.08 wt.% Fe2O3, 29.62–32.42 wt.% SiO2 and 55.20–59.71 wt.% Al2O3. Al is the most likely substituent for Si, which shows a minor deficiency at the tetrahedral sites in most dumortierites. The major variations in the mineral chemistry can be described by the coupled substitutions Mg + Ti = 2AlVI, 3Mg = 2AlVI and possibly Mg + H = AlVI. Favoured by low ƒO2 prevailing conditions a significant part of total iron in dumortierites at one locality is present as Fe2+ giving evidence for the Fe2+ + SiIV = AlIV + AlVI tschermakite substitution. FeMg−1 substitution is considered to be limited. Ti-rich dumortierites coexist with rutile, ilmenite or titaniferous magnetite. The development of dumortierite from orthoamphibole correlates with an observed decrease of Al, Mg and Na and increase of Si and Fe in orthoamphibole towards dumortierite.
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Do Campo, Margarita, Fernando Nieto, Guillermo L. Albanesi, Gladys Ortega, and Rubén Monaldi. "Outlining the thermal posdepositional evolution of the Ordovician successions of northwestern Argentina by clay mineral analysis, chlorite geothermometry and Kübler index." Andean Geology 44, no. 2 (May 31, 2017): 179. http://dx.doi.org/10.5027/andgeov44n2-a04.
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El Arbaoui, Amal, Ismaïla N’Diaye, Zaineb Hajjar, Amina Wafik, Abdelhak Boutaleb, Said Ilmen, Abderrahim Essaifi, and Mohammed Bouabdellah. "Fluid Origin and Evolution of the Roc Blanc Silver Deposit (Jebilet Massif, Variscan Belt, Morocco): Constraints from Geology and Fluid Inclusions." Geofluids 2022 (December 7, 2022): 1–22. http://dx.doi.org/10.1155/2022/3882516.
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The Roc Blanc Pb-Zn-Ag-Au vein deposit is located in the NW of Marrakech, in the Central Jebilet massif. It is spatially related to Bramram-Tabouchennt-Bamega (BTB) granodioritic pluton (ca. 330 Ma) metamorphism aureole. The main veins hosted in black shales are oriented N-S to NNW-SSE. Pb-Zn-Ag-Au ore is associated with quartz, chlorite, sericite, and carbonate gangue minerals. Two major stages of ore deposition were distinguished. The preore stage (stage I) comprises two quartz-mineralised vein generations with Fe, As, Zn, and Cu ores (vg1 and vg2). The main ore stage (stage II) consists mainly on Ag, Au, Pb, Zn, Cu, and Sb ores, which is hosted by carbonaceous vein (vg3) and by two late quartz generations veins (vg4 and vg5 with a geodic quartz). Three types of fluid inclusions have been recognized in silver mineralisation bearing quartz veins according to petrographic investigations, microthermometry, and Raman spectroscopy studies: (i) liquid-rich H2O-N2-CH4±CO2-(salt) fluid inclusions (type 1), (ii) vapour-rich H2O-CO2-CH4-N2-(salt) fluid inclusions (type 2), and (iii) aqueous H2O-(salt) fluid inclusions (type 3). The interpretation of fluid inclusion data shows a mixing of two fluids that are metamorphic and surface to subsurface origin, trapped at boiling state. The first mineralised stage was deposited at 350 ± 20 ° C (this temperature of ore deposition was supported also by chlorite geothermometry) with salinity of 13.7 wt% NaCl equiv., while the deposition of the argentiferous stage, which consists of the main economic mineralisation of the Roc Blanc deposit, occurs during decreasing temperature at 150°C with a salinity of 12.1 wt% NaCl equiv. The all-mineralised ore was deposited at relatively low pressure, below ~1-1.1 kbar. So, fluid dilution and cooling are probably the main factor for silver deposition in the Roc Blanc polymetallic vein deposit. In addition, fluid inclusion studies reveal that the mineralising fluid corresponds to a mixture of metamorphic fluid (H2O-CH4-N2-CO2) with surface to subsurface aqueous gas-free fluids (H2O-salt, meteoric, or brine).
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Chaumba, Jeff B. "Inferences on late-stage evolution of the Russell Lake Allochthon and the Soapstone Ridge Complex in Georgia, Southern Appalachians, based on chlorite geothermometry." International Journal of Earth Sciences 109, no. 5 (April 9, 2020): 1639–57. http://dx.doi.org/10.1007/s00531-020-01861-5.
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Voudouris, P., A. Xinou, C. Kanellopoulos, M. Kati, C. Mavrogonatos, and P. Lyberopoulos. "A new occurrence of pyrophanite from the amphibolite-hosted skarn in Western Kimmeria, Xanthi, Northern Greece." Bulletin of the Geological Society of Greece 47, no. 1 (September 5, 2013): 487. http://dx.doi.org/10.12681/bgsg.11027.
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A new occurrence of pyrophanite (MnTiO3) in Greece is described from the garnetclinopyroxene-wollastonite exoskarn of western Kimmeria. Hostrock of the pyrophanite-bearing skarn is amphibolite (retrogressed eclogites) of the Nestos suture zone in the Rhodope massif. In addition endo- and exo-skarns occur both in the Xanthi granodiorite and the surrouding marbles and consinst of diopside-vesuvianitequartz and wollastonite-garnet-calcite-quartz respectively. Pyrophanite formed in the prograde stage, together with garnet, pyroxene, wollastonite, titanite, zircon, rutile, thorite and ouranothorianite. Retrograde minerals are quartz, epidote, calcite, hematite, and sulfides. Chlorite-geothermometry revealed temperatures in the range from 300 to 350 oC for the retrograde event. Calcic garnets (andraditegrossular solid solutions) from the prograde amphibolite-hosted skarn are chemically zoned with either isotropic or anisotropic cores surrounded by non-cubic anisotropic rims, thus suggesting chemical disequilibrium or disordering phenomena during crystal growth. The pyrophanite crystals are included in titanite and are accompanied by U-rich thorium minerals (uranothorianite, thorite) and by rutile. Electron microprobe analyses indicate that the studied pyrophanites are solid solutions between end-member pyrophanite and ilmenite, with isomorphous substitution of Mn2+ by Fe2+. No Mg has been detected (geikielite end-member). The alteration of pyrophanite and rutile to titanite suggests an increase of fO2 values of the fluids, probably due to increased incursion of meteoric waters to the system. The assemblage thorite, uranothorianite, pyrophanite and zircon indicates a magmatic contribution from the Xanthi granodiorite.
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Owens, E. O., and R. W. Hodder. "Aluminosilicate mineral assemblages in the Cargo Muchacho Mountains, southern California: metasomatism and gold concentration associated with magmatism and deformation in mesozonal environments." Canadian Journal of Earth Sciences 31, no. 2 (February 1, 1994): 310–22. http://dx.doi.org/10.1139/e94-029.
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Aluminous, kyanite-bearing mineral assemblages with more than 30% Al2O3 and less than 2% CaO + Na2O + K2O, like aluminous occurrences elsewhere, are spatially associated with gold deposits in the Cargo Muchacho Mountains, southeastern California. They are part of a zoned sequence of mineral assemblages that grade from regional amphibolite-facies quartzofeldspathic gneiss into locally occurring quartz–oligoclase–biotite–epidote–magnetite (feldspar zone), quartz–muscovite–biotite–magnetite–apatite–tourmaline (muscovite zone), and quartz–kyanite–magnetite–rutile–apatite–tourmaline–lazulite (kyanite zone). Field relations show that the mineral assemblages developed during emplacement of a Jurassic metaluminous–peraluminous plutonic suite, and that magmatism and aluminosilicate formation were partly contemporaneous with crosscutting low-angle shear zones.Mineral assemblage variation and bulk rock compositions point to aluminosilicate formation by pervasive H -ion metasomatism. Replacement of biotite by magnetite and variation in biotite Fe/(Fe+Mg) from 0.51 in the feldspar zone to 0.38 in the kyanite zone indicate oxidation was important during metasomatism. Calculated pH is 6.5 or less, and oxygen fugacity is 10−27 to 10−18 bars (1 kbar = 100 MPa) for fluids in equilibrium with the kyanite zone. Staurolite-bearing kyanite zone limits pressures to more than 400 MPa, and garnet–biotite geothermometry gives temperatures of 500–550 °C for metasomatism. The data are consistent with an origin by oxidizing, near-neutral magmatic fluids arising from crystallization of Jurassic mesozonal metaluminous–peraluminous magma. The high oxidation state suggests gold would have been transported to more reduced chlorite- and pyrite-bearing assemblages distal to the aluminosilicates.
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Portella, Yuri de Melo, Federica Zaccarini, and Giuseppe Etiope. "First Detection of Methane within Chromitites of an Archean-Paleoproterozoic Greenstone Belt in Brazil." Minerals 9, no. 5 (April 29, 2019): 256. http://dx.doi.org/10.3390/min9050256.
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Abiotic methane is widely documented in seeps, springs and aquifers associated with mafic-ultramafic rocks in Phanerozoic ophiolites, peridotite massifs and intrusions worldwide. Chromitites in ophiolites, in particular, have been interpreted as the rocks potentially generating methane though CO2 hydrogenation. Here, we document, for the first time, the presence of methane within chromitites in South America. We analyzed, through milling and gas extraction, the content of gas occluded in Cedrolina chromitite samples, belonging to the Pilar de Goiás greenstone belt in Brazil. The chromitites display significant gas concentrations up to 0.31 µg CH4/grock and 2800 ppmv of hydrogen, while the host talc schist is devoid of gas. Stable C isotope composition of methane (δ13C from −30 to −39.2‰) and the absence of organic-matter rich metasediments in the region suggest an abiotic origin. Hydrogen and methane concentrations appear related to high-Cr chromite modal content and to the presence of Ni-sulfides/alloys, which are potential catalysts of CO2 hydrogenation at temperatures above 200 °C. Accessory ruthenium-bearing minerals occurring in the chromitites could also act as catalysts, even at lower temperatures. Geothermometry of chlorite found in the chromitites constrains serpentinization at ~250 °C, during lower greenschist facies retrometamorphism. Hydrogen could be autochthonous, and thus formed under similar temperature, which we hypothesize represents the upper limit for abiotic methane generation in the area (250 °C). The Cedrolina chromitites are the first example of CH4 occurrence in ultramafic rocks related to an Archean-Paleoproterozoic greenstone belt. This may imply that serpentinized Cr-rich chromitites could have been sources of methane for the early Earth’s atmosphere.
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Brueckner, Stefanie M., Gregory Johnson, Stephanie Wafforn, Harold Gibson, Ross Sherlock, Christina Anstey, and Ken McNaughton. "Potential for Volcanogenic Massive Sulfide Mineralization at the A6 Anomaly, North-West British Columbia, Canada: Stratigraphy, Lithogeochemistry, and Alteration Mineralogy and Chemistry." Minerals 11, no. 8 (August 11, 2021): 867. http://dx.doi.org/10.3390/min11080867.
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The Middle Jurassic A6 Anomaly is located 30 km southeast of Eskay Creek, north-central British Columbia and consists of thick, altered felsic igneous rocks overlain by a mafic volcano-sedimentary package. Lithogeochemistry on igneous rocks, X-ray diffraction on altered felsic units, and electron probe microanalysis and secondary ion mass spectrometry on illite and quartz were applied to explore the volcanogenic massive sulfide (VMS) potential, characterize alteration, and determine fluid conditions at the A6 Anomaly. Lithogeochemistry revealed calc-alkaline rhyodacite to trachyte of predominantly FII type, tholeiitic basalts with Nb/Yb < 1.6 (i.e., Group A), and transitional to calc-alkaline basalts and andesites with Nb/Yb > 2.2 (i.e., Group B). The felsic units showed weakly to moderately phyllic alteration (quartz–illite with minor orthoclase and trace chlorite–pyrite–calcite–barite–rutile). Illite ranged in composition from illite/smectite (K = 0.5–0.69 apfu) to almost endmember illite (K = 0.69–0.8 apfu), and formed from feldspar destruction by mildly acidic, relatively low temperature, oxidized hydrothermal fluids. The average δ18O composition was 10.7 ± 3.0‰ and 13.4 ± 1.3‰ relative to Vienna Standard Mean Ocean Water for illite and quartz, respectively. Geothermometry involving illite composition and oxygen isotope composition on illite and quartz yielded average fluid temperatures of predominantly 200–250 °C. Lithogeochemical results showed that the A6 Anomaly occurred in a late-Early to Middle Jurassic evolving back-arc basin, further east then previously recognized and in which transitional to calc-alkaline units formed by crustal assimilation to enriched Mid-Ocean Ridge Basalt (EMORB) (i.e., felsic units, Group B), followed by thinning of the crust resulting in tholeiitic normalized MORB basalts (i.e., Group A) with a minor crustal component. The alteration assemblage is representative of distal footwall alteration, and metal transport in this zone was limited despite favorable temperature, pH, and redox state, indicating a metal depleted source (i.e., felsic units).
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Pérez-Cáceres, Irene, David Jesús Martínez Poyatos, Olivier Vidal, Olivier Beyssac, Fernando Nieto, José Fernando Simancas, Antonio Azor, and Franck Bourdelle. "Deciphering the metamorphic evolution of the Pulo do Lobo metasedimentary domain (SW Iberian Variscides)." Solid Earth 11, no. 2 (April 3, 2020): 469–88. http://dx.doi.org/10.5194/se-11-469-2020.
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Abstract. The Pulo do Lobo domain is one of the units exposed within the orogenic suture zone between the Ossa-Morena and the South Portuguese zones in the SW Iberian Variscides. This metasedimentary unit has been classically interpreted as a Rheic subduction-related accretionary prism formed during pre-Carboniferous convergence and eventual collision between the South Portuguese Zone (part of Avalonia) and the Ossa-Morena Zone (peri-Gondwanan terrane). Discrete mafic intrusions also occur within the dominant Pulo do Lobo metapelites, related to an intra-orogenic Mississippian transtensional and magmatic event that had a significant thermal input. Three different approaches have been applied to the Devonian–Carboniferous phyllites and slates of the Pulo do Lobo domain in order to study their poorly known low-grade metamorphic evolution. X-ray diffraction (XRD) was used to identify the mineralogy and measure crystallographic parameters (illite “crystallinity” and K-white mica b-cell dimension). Compositional maps of selected samples were obtained from electron probe microanalysis, which allowed for processing with XMapTools software, and chlorite semiempirical and thermodynamic geothermometry was performed. Thermometry based on Raman spectroscopy of carbonaceous material (RSCM) was used to obtain peak temperatures. The microstructural study shows the existence of two phyllosilicate growth events in the chlorite zone, the main one (M1) related to the development of a Devonian foliation S1 and a minor one (M2) associated with a crenulation cleavage (S2) developed in middle–upper Carboniferous times. M1 entered well into epizone (greenschist facies) conditions. M2 conditions were at lower temperature, reaching the anchizone–epizone boundary. These data accord well with the angular unconformity that separates the Devonian and Carboniferous formations of the Pulo do Lobo domain. The varied results obtained by the different approaches followed, combined with microstructural analysis, provide different snapshots of the metamorphic history. Thus, RSCM temperatures are higher in comparison with the other methods applied, which is interpreted to reflect a faster re-equilibration during the short-lived thermal Mississippian event. Regarding the metamorphic pressure, the data are very homogeneous: very low celadonite content (0 %–10 %) in muscovite (and low values of K-white mica b-cell dimension; 8.995 Å mean value), indicating a low pressure–temperature gradient, which is unexpected in a subduction-related accretionary prism. Highlights A multidisciplinary approach has been applied to study the metamorphism of the Pulo do Lobo metapelites. Devonian metamorphism entered epizone conditions. Carboniferous metamorphism reached the anchizone–epizone boundary. The inferred low-pressure gradient is incompatible with a subduction-related accretionary prism.
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Cathelineau, M. "Cation site occupancy in chlorites and illites as a function of temperature." Clay Minerals 23, no. 4 (December 1988): 471–85. http://dx.doi.org/10.1180/claymin.1988.023.4.13.
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AbstractThe relationships between the composition and the crystallization temperature of chlorites and illites have been investigated in different geothermal fields and in particular the Los Azufres system in Mexico, considered to be a natural analogue to experimental laboratories, as the main changes in physical and chemical conditions and mineralogy are related to progressively increasing temperature with depth. Temperature was estimated from combined geothermometric approaches, and especially from fluid inclusion studies on quartz coexisting with clays. The Al(IV) content in the tetrahedral site of chlorites, and the K content and total interlayer occupancy of illites increase with temperature. These chemical changes are mainly related to the marked decrease in the molar fraction of the Si(IV)-rich end-members (kaolinite for chlorites, and pyrophyllite for illites) which become negligible at ∼300°C. Other chemical changes, such as the variation in Fe and Mg contents, are partly influenced by temperature, but are strongly dependent on the geological environment, and consequently on the solution composition. The empirical relationships between chemical variables and temperature were calibrated from 150–300°C, but extrapolations at lower and higher temperatures seem possible for chlorites. Such geothermometers provide tools for estimating the crystallization temperature of the clays, and are important for the study of diagenetic, hydrothermal and low-T metamorphic processes.
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Cathelineau, M. "The chlorite and illite geothermometers." Chemical Geology 70, no. 1-2 (August 1988): 182. http://dx.doi.org/10.1016/0009-2541(88)90734-6.
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Árkai, P., and D. Sadek Ghabrial. "Chlorite crystallinity as an indicator of metamorphic grade of low-temperature meta-igneous rocks: a case study from the Bükk Mountains, Northeast Hungary." Clay Minerals 32, no. 2 (June 1997): 205–22. http://dx.doi.org/10.1180/claymin.1997.032.2.04.
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AbstractX-ray diffraction chlorite crystallinity (ChC) indices and major element chemical compositions of chlorites and bulk rocks were determined and correlated in meta-igneous rocks from different Mesozoic formations in various tectonic units of the Bükk Mountains, NE Hungary. The rocks, of basic to acidic compositions, range from ocean-floor metamorphic prehnite-pumpellyite facies (diagenetic zone) through regional metamorphic prehnite-pumpellyite facies (anchizone) up to the regional metamorphic pumpellyite-actinolite and greenschist facies (epizone). As in the case of meta-sedimentary rocks, chlorite crystallinity can be applied as an empirical, complementary petrogenetic tool to determine relative differences in grades of low-temperature meta-igneous rocks. Electron microprobe and XRD data show that ChC is controlled mainly by the decreasing amounts of contaminants (mixed-layered components or discrete, intergrown phases of mostly smectitic composition) in chlorite with advancing metamorphic grade, up to the epizone. The apparent increase in calculated Aliv content of chlorite with increasing temperature is related to the decrease of these contaminants, as stated earlier by Jiang et al. (1994). On the basis of the significant correlations found between ChC and temperatures, derived by the chlorite-Aliv geothermometer of Cathelineau (1988), both methods may be used for estimating the approximate temperatures of metamorphism, in spite of the contrasting interpretation of chemical data from chlorites obtained by electron microprobe analyses. After determining the effects of changing bulk chemistry on chlorite composition and ChC, the chlorite crystallinity method may complement the correlation of the illite crystallinity-based zonal classification of meta-sediments and the mineral facies classification of meta-igneous rocks.
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MIZUTA, Toshi. "The Best Article Award 2010 of the Society of Resource Geology was Presented to Atsuyuki Inoue, Kyohei Kurosawa, and Tamao Hatta, for the Following Paper: Application of chlorite geothermometry to hydrothermal alteration in Toyoha geothermal system, South." Resource Geology 61, no. 3 (June 23, 2011): 311. http://dx.doi.org/10.1111/j.1751-3928.2011.00168.x.
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Myšľan, Pavol, and Peter Ružička. "Sľudy a chlority ako indikátory podmienok metamorfózy karbonátových hornín gelnickej skupiny južného gemerika (Slovenská republika)." Bulletin Mineralogie Petrologie 30, no. 1 (2022): 108–23. http://dx.doi.org/10.46861/bmp.30.108.
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Investigated metacarbonates are located in the Early Paleozoic rocks of Southern Gemericum unit, Slovakia. Metacarbonates are part of Vlachovo Formation (Tichá Voda, Stará Voda) and Bystrý potok Formation (Betliar, Čučma, Malá Hekerová, Smolník - Mária Terézia, Holec). Detailed studies indicated metamorphic pressure-temperature (P-T) conditions of 3 - 7 kbar at 330 - 370 °C for the Gelnica Group. The calculated P-T conditions were verified using chlorite geothermometer and phengite geobarometer. Mineral association of metacarbonates consists of Si rich (3.10 - 3.35 apfu) phengitic micas, Fe-Mg chlorites (clinochlore and chamosite), quartz, K-feldspars and accessory fluorapatite. Micas and Mg-Fe chlorites originated from metamorphic recrystallization of clay material with incorporations of basic pyroclastic material during the regional metamorphosis of pelitic protolith, which sedimented continuously with carbonates. Metacarbonates belong to the upper parts of Gelnica Group, which were metamorphosed under the greenschist facies conditions.
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Inoue, Atsuyuki, Alain Meunier, Patricia Patrier-Mas, Cecile Rigault, Daniel Beaufort, and Philippe Vieillard. "Application of Chemical Geothermometry to Low-Temperature Trioctahedral Chlorites." Clays and Clay Minerals 57, no. 3 (June 1, 2009): 371–82. http://dx.doi.org/10.1346/ccmn.2009.0570309.
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Trincal, Vincent, and Pierre Lanari. "Al-free di-trioctahedral substitution in chlorite and a ferri-sudoite end-member." Clay Minerals 51, no. 4 (September 2016): 675–89. http://dx.doi.org/10.1180/claymin.2016.051.4.09.
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AbstractA compilation of Fe3+-bearing chlorite analyses is used: (1) to investigate the Alfree di-trioctahedral (AFDT) substitution 2Fe3++□= 3(Mg,Fe2+) in chlorite; and (2) to estimate the composition of a ferri-sudoite end-member (Si3Al)[(Fe2+,Mg)2□Al]O10(OH)8within the chlorite solid-solution domain. According to our observations, up to two Fe3+cations might be allocated in the M2-M3 chlorite sites by the substitution AFDT, which does not involve Al. These unexpected observations were made possible by the development of μXANES techniques allowingin situmeasurements ofXFe3+(Fe3+/(Fe2++ Fe3+)) in heterogeneous chlorite. Although further studies are required to confirm the crystallographic position of Fe3+ and refine its ionic/ magnetic behaviour in chlorite, this development creates opportunities for developing new geothermometers.
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Battaglia, Stefano. "Applying X-Ray Geothermometer Diffraction to a Chlorite." Clays and Clay Minerals 47, no. 1 (1999): 54–63. http://dx.doi.org/10.1346/ccmn.1999.0470106.
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Ait-Ouali, Abdelkader, Salima Ouali, MM Hadjiat, and Khaled Imessad. "The main geothermal reservoirs in the south Algeria and their interest for local economic development." E3S Web of Conferences 80 (2019): 01006. http://dx.doi.org/10.1051/e3sconf/20198001006.
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The study area is one of the important geothermal provinces in south Algeria. It is characterized by a hot arid climate with intense dryness and very high evaporation rates. The Albian geothermal system is exploited by the wells mainly for domestic and agricultural purposes. The sandstone Continental Intercalary (CI) formation constitutes the reservoir for the Albian aquifer, covering an area of 600,000 km2. This reservoir is covered by calcareous formations which yield the chemical characteristics of highly mineralized Na-Cl type representing the deep thermal waters and Ca-SO4 type determined the presence of evaporate lithology . For a better understanding of geothermal reservoir characteristic, a multidisciplinary approach was adopted, including hydrogeochemistry and geothermometry. More than fifty samples collected from wells recently in 2017 with a temperature average between 38 and 60° C and conductivities range from 2010 to 3460 μS/cm. Geochemical analysis of those thermal waters exhibits a certain degree of salinity with sodium-chloride type waters domination. The maximal geothermal reservoir temperature estimated using geothermometry is about 120°C.