Geochemistry International最新文献

{"title":"Geochemistry, Monazite (U–Pb–Th) Geochronology, and P-T Pseudosection Modelling of Two-Pyroxene Mafic Granulite from Sonapahar, Shillong Meghalaya Gneissic Complex, India: Implication for Tectono-Metamorphic Evolution and Global Pan-African Correlation","authors":"Bikash Mahanta,&nbsp;Divya Prakash,&nbsp;Manish Kumar,&nbsp;Saurabh Singh,&nbsp;Rajeev Kumar Pandey,&nbsp;Chandra Kant Singh,&nbsp;Suparna Tewari","doi":"10.1134/S0016702924700319","DOIUrl":"10.1134/S0016702924700319","url":null,"abstract":"<p>Granulites exposed in high-grade regional metamorphic belts and exhumed as xenoliths in basaltic pipes are considered as window into the deep crust thus play a key role in constraining models of crustal processes and evolution. Here we present a detailed investigation of the tectono-metamorphic history of the two-pyroxene mafic granulite located in the southern region of the Sonapahar area. This involves conducting monazite chemical dating, analyzing petrological and geochemical characteristics, applying geothermobarometry, performing phase equilibria modeling, and tracing a pressure-temperature (<i>P-T</i>) path. Metamorphic <i>P-T</i> conditions estimated for the mafic granulite using conventional thermobarometer and winTWQ shows temperature in excess of 800°C and pressure of about 8.6 kbar, stand for high temperature granulite facies metamorphism. The metamorphic evolution path obtained from <i>P-T</i> pseudosection suggest a clockwise <i>P-T</i> evolution path, thus signify isothermal decompression and indicate rapid upliftment. Geochemical study of trace and rare earth elements (REE), suggest protolith is of tholeiite basalt in nature that is derived from back arc basin setting near to subduction zone. Additionally, the analyzed rock was examined using primitive mantle-normalized trace element spider diagram. The results indicate an enrichment in large-ion lithophile elements (Th, U, K, Pb) and a depletion in high field-strength elements (Nb, Ta, Ti). The presence of negative anomalies in Nb and Ti, coupled with elevated values of Th, K, and Pb, suggests the possibility of crustal contamination. Monazite chemical data from the studied rock reveals a peak metamorphism age of 521.3 ± 4.20 Ma, which corresponds to the Kuunga Orogeny in the later phase of global Pan-African collision.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 6","pages":"574 - 608"},"PeriodicalIF":0.7,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140836003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sources and Evolution of Miocene–Pleistocene Alkaline Magmatism in the Northeast Part of the Arabian Plate: Evidence from Sr–Nd–Pb Isotope Data and K–Ar Geochronometry","authors":"A. V. Chugaev,&nbsp;A. V. Parfenov,&nbsp;V. A. Lebedev,&nbsp;I. V. Chernyshev,&nbsp;V. Oyan,&nbsp;Y. Özdemir,&nbsp;E. Oyan,&nbsp;Yu. V. Gol’tsman,&nbsp;I. V. Rassokhina,&nbsp;B. I. Gareev,&nbsp;G. A. Batalin,&nbsp;S. B. Pavlidis","doi":"10.1134/S0016702924020034","DOIUrl":"10.1134/S0016702924020034","url":null,"abstract":"<p>A geochronological and isotope–geochemical study of alkaline basalts from three areas of young magmatism within the northeastern part of the Arabian Plate (Southeastern Turkey), Batman, Kurtalan and Alemdağ, was carried out. The obtained isotope data have indicated that the volcanism in the studied region developed over a 5-Ma period from the end of Miocene to the middle Pleistocene during four pulses separated by breaks in magmatic activity: 6.1–4.9 Ma (Batman area, hawaiites), ~3.0 Ma (Alemdağ plateau, phase I, basalts), 2.0–1.9 Ma (Alemdağ plateau, phase II, tephrites), and 1.5–1.3 Ma (Alemdağ plateau, phase III, basalts; Kurtalan area, basalts). A comparison of spatial–temporal changes of magmatic activity evolution in the studied part of the Arabian Plate and within the largest basalt plateau of Arabian foreland, Karacadağ Plateau, located to the west, was carried out. The results of Sr–Nd–Pb isotope–geochemical studies show that the development of young basalt volcanism in the Arabian Plate was characterized at different time by the contribution of various mantle sources in magma generation under this region. Initial pulses of magmatic activity are associated with melting of Arabian subcontinental lithospheric mantle (SCLM). The processes of fractional crystallization combined with crustal assimilation (AFC) have played an important role in the petrogenesis of lavas as well. Later, a deep mantle source (PREMA) with a depleted isotopic composition played a leading role in the formation of basaltic magmas of increased alkalinity. The melts generated by this source were mixed with the SCLM material in various proportions at different stages of magmatism with a limited participation of AFC processes in the petrogenesis of the rocks. It was concluded that young basalt volcanism of increased alkalinity in the northeast of the Arabian Plate is not related to the collision of the Eurasian and Arabian plates genetically, but presumably manifested here as a result of the migration of the initial rift geodynamic setting from the Red Sea basin to the north along Levantine and East Anatolian transform faults due to directed convection flows in the lower part of mantle under this part of the Earth.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 2","pages":"99 - 123"},"PeriodicalIF":0.7,"publicationDate":"2024-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140567750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental Study of Pargasite NaCa2(Mg4Al)[Si6Al2O22](OH)2 Stability at T = 1000–1100°C and Pressure up to ({{P}_{{{{{text{H}}}_{{text{2}}}}{text{O}}}}}) = 5 Kbar","authors":"V. N. Deviatova,&nbsp;A. N. Nekrasov,&nbsp;G. V. Bondarenko","doi":"10.1134/S0016702924020046","DOIUrl":"10.1134/S0016702924020046","url":null,"abstract":"<p>Pargasite stability was experimentally studied in IHPV at <span>({{P}_{{{{{text{H}}}_{{text{2}}}}{text{O}}}}})</span> = 2 kbar and temperatures of 1000 to 1100^oC, with equilibrium approached from above and below. Calcic amphibole was used to experimentally model processes that occur in a volcanic chamber at pressures up to 5 kbar. The phase diagram of pargasite has been refined. It has been established that the stability of pargasite is controlled by three reactions. (1) At low water pressures of less than 1 kbar, the dehydration reaction <i>Prg</i> = <i>Fo</i> + <i>Sp</i> + <i>Di</i> + <i>Ne</i> + <i>An</i> + H₂O proceeds. (2) At water pressures higher than 1.2–1.5 kbar and a temperature of about 1100°C, the decomposition of pargasite is controlled by its incongruent melting <i>Prg</i> = <i>Fo</i> + <i>Sp</i> + {<i>Di</i> + <i>Ne</i> + <i>An</i>}^<i>L</i> + H₂O. (3) The third reaction <i>Prg</i> + <i>L</i> = <i>Fo</i> + <i>Sp</i> + <i>Di</i> + {<i>Ne</i> + <i>Pl</i>}^<i>L</i> + H₂O occurs within the same pressure range as the previous one but at lower temperatures of about ~1050°C. The reaction controls the pargasite liquidus and is caused by interaction between amphibole and coexisting melt. The liquidus of pargasite seems to most strongly depend on the activity of silica <span>({{a}_{{{text{Si}}{{{text{O}}}_{{text{2}}}}}}})</span> in the melt.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 2","pages":"140 - 154"},"PeriodicalIF":0.7,"publicationDate":"2024-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140567755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Destinezite: A Physicochemical and Calorimetric Study","authors":"Yu. D. Gritsenko,&nbsp;L. P. Ogorodova,&nbsp;M. F. Vigasina,&nbsp;L. V. Melchakova,&nbsp;D. A. Ksenofontov,&nbsp;S. K. Dedushenko","doi":"10.1134/S0016702924030042","DOIUrl":"10.1134/S0016702924030042","url":null,"abstract":"<p>Destinezite (<span>({text{Fe}}_{{1.97}}^{{3 + }})</span>Al_0.02)(PO₄)_0.99(SO₄)_0.90(OH)_1.20⋅5.97H₂O (Czech Republic) has been studied by thermal and electron-microprobe analyses, X-ray powder diffraction, and by IR, Raman, and Mössbauer spectroscopy. The enthalpy of formation of destinezite <span>({text{Fe}}_{2}^{{3 + }})</span>(PO₄)(SO₄)(OH)⋅6H₂O from elements ∆_f<i>H</i>⁰(298.15 K) = –4258 ± 12 kJ/mol was determined by the method of solution calorimetry in lead borate 2PbO⋅B₂O₃ melt on a Setaram (France) Calvet microcalorimeter. The value of its absolute entropy <i>S</i>⁰(298.15 K) = 462.0 J/(mol K) was estimated, the entropy of formation ∆_f<i>S</i>⁰(298.15 K) = –2054 J/(mol K), and the Gibbs energy of formation from the elements ∆_f<i>G</i>⁰(298.15 K) = –3646 kJ/mol were calculated.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 3","pages":"274 - 283"},"PeriodicalIF":0.7,"publicationDate":"2024-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140568112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lithological, Mineralogical, and Geochemical Features of the Lower Maeotian Sediments of the Kazantip Nature Reserve, Crimea","authors":"A. I. Antoshkina,&nbsp;L. V. Leonova,&nbsp;O. V. Valyaeva,&nbsp;Y. S. Simakova","doi":"10.1134/S0016702924030029","DOIUrl":"10.1134/S0016702924030029","url":null,"abstract":"<p>The paper presents the results of a study of carbonate and sulfate–carbonate–clayey rocks of the Lower Maeotian in the sections of the bays of Cape Kazantip using a complex of analytical methods. It is established that the greatest variation of chemical, bituminological, phase, and carbon-isotope composition is characterized by carbonate–clay and clayey rocks of the section bottom. It is proved that the initial OM was accumulated mainly under reducing conditions, but has some variations in composition; it is characterized by a low degree of its catagenetic transformation, which indicates the preservation of the primary isotopic composition. The diverse phase composition of the clay fraction is revealed: dioctahedral illite, kaolinite, chlorite, glauconite, and weakly ordered mixed-layer formations of illite/smectite type with different ratios of illite and smectite components and varying degrees of ordering. Modeling of their diffraction profiles showed that the illite/smectite structure may indicate significant depths of sediment mobilization by mud volcanoes. The isotopic composition of the ¹³С_org ranges widely from –33.72 to –19.27‰ the mode being –22.1…–24.93‰. The isotopic composition of ¹³С_org below –25.6‰ may be related to the entry of isotope-light mass of methane-oxidizing bacteria into the OM. It was revealed that variations of isotopic composition curves ¹³С_carb and ¹³С_org along the section of the studied rocks are rarely characterized by unidirectional (positive or negative) variations and have different trends along the section. Direction of the ¹³С_carb isotope composition curve with some variations has a pronounced upward trend toward heavier weighting, whereas the isotopic values of the ¹³С_org reveals reverse tendency. The results obtained prove that the revealed variations in the composition of OM and carbon isotope composition in the Lower Maeotian sections of Cape Kazantip reflect variations in the sedimentation conditions of temperature, salinity, freshwater ingression, bioproductivity fluctuations, and the influence of local gas–fluid deposition. It is proposed to use such accessory minerals as zircon, monazite, and ilmenite as an indicator of mud paleovolcanism.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 3","pages":"284 - 299"},"PeriodicalIF":0.7,"publicationDate":"2024-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140567744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemistry and Formation Conditions of Mesoarchean Banded Iron Formations (BIF-1) from the Kostomuksha Greenstone Belt, Karelian Craton","authors":"A. I. Slabunov,&nbsp;N. S. Nesterova,&nbsp;O. A. Maksimov","doi":"10.1134/S0016702924030054","DOIUrl":"10.1134/S0016702924030054","url":null,"abstract":"<div><p>Three variably old groups of banded iron formation (BIF) are known in the Kostomuksha Greenstone Belt (KGB) of the Karelian Craton. This paper deals with the earliest of them, Mesoarchean (2.87–2.81 Ga) BIF-1. BIF-1 occurs among the komatiite–basalt unit of the KGB. BIF-1 consists mainly of quartz and magnetite, with varying amounts of amphibole, biotite, and garnet; the variations of SiO₂ (48.3–58.6 wt %) and <span>({text{F}}{{{text{e}}}_{{text{2}}}}{text{O}}_{{text{3}}}^{{text{T}}})</span> (21.34–33.82 wt %) suggest that the rocks are BIF. BIF-1 of the KGB, as well as most Archean BIFs, contain high <span>({text{F}}{{{text{e}}}_{{text{2}}}}{text{O}}_{{text{3}}}^{{text{T}}})</span> concentration, display a contrasting positive Eu anomaly, lack of Ce anomaly, and the depletion of LREE relative to HREE. However, they differ from other BIFs in the higher Al₂O₃, TiO₂, MgO, K₂O, Cr, Ni, Zr, Ba, Cu and Zn concentrations. BIF-1 was formed in a marine basin at an anoxic atmosphere due to hydrothermal fluids, the proportion of which varies from 20 to 80%, and a terrigenous component derived mainly from basalts, komatiites, and dacites of host rocks. Mesoarchean BIF-1 of the KGB was accumulated in a small rift structures within an oceanic volcanic plateau, the formation of which is associated with the influence of a mantle plume on the oceanic lithosphere.</p></div>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 3","pages":"245 - 266"},"PeriodicalIF":0.7,"publicationDate":"2024-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140567751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Variability of Stishovite Genesis under Terrestrial Conditions: Physicogeochemical Aspects","authors":"Yu. A. Litvin,&nbsp;A. V. Spivak,&nbsp;A. V. Kuzyura","doi":"10.1134/S0016702924020071","DOIUrl":"10.1134/S0016702924020071","url":null,"abstract":"<p>A model of the genesis of stishovite and other SiO₂ phases in terrestrial matter is developed; it combines the physicochemical and geodynamic conditions of their formation. Based on the experimental data, a <i>P–T</i> diagram of SiO₂ polymorphs in combination with the boundaries of geospheres and geotherm was plotted. Stishovite and other SiO₂ phases of cosmic-impact synthesis were buried in the early Earth during the period of meteorite accretion (50 Ma). These SiO₂ phases are completely assimilated by melts of the pyrolite global magma ocean that existed for 500 Ma. By 2.0 Ga, the magma ocean crystallized, and the Earth’s crust, upper mantle, transition zone, and lower mantle with layer D” (with seismic boundaries between them) were formed. During this period, the main mass of the Earth’s core was separated, which completed by 2.7 Ga. As a result, the gravitational field intensified, which contributed to the fractional ultramafic–mafic evolution of mantle magmas with peritectic reactions of ringwoodite–akimotoite in the transition zone and bridgmanite in the lower mantle with melts and the formation of stishovite (shown experimentally at 20 and 26 GPa). These reactions in diamond-forming carbonate–silicate–carbon melts provided the formation of stishovite, which was captured as a paragenetic inclusion by diamonds and transported to the Earth’s surface by magmas. The genesis of stishovite under the terrestrial conditions is controlled by global mantle convection as well. The subduction of lithospheric plates to layer D'' near the liquid core was accompanied by the formation of stishovite, and then its transformation into poststishovite phases. When superplumes rise from layer D'' to the Earth’s crust, the peritectic reactions of postperovskite and bridgmanite, and then ringwoodite–akimotoite, with melts are likely to form stishovite and cause its subsequent transformation into low-pressure SiO₂ phases. With the emergence of the Earth’s crust, the impact-meteorite genesis of stishovite resumes. Stishovite that formed under the terrestrial conditions appears as an inclusion in ultradeep diamonds on the Earth’s surface. Stishovite of cosmic-impact synthesis is preserved in meteorite craters. In both cases, stishovite is a metastable phase.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 2","pages":"124 - 139"},"PeriodicalIF":0.7,"publicationDate":"2024-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140567756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Partition of Trace Elements between Minerals and Melt: Parameterization of Experimental Data on Olivine, Pyroxene, and Feldspars","authors":"A. V. Girnis","doi":"10.1134/S0016702924030030","DOIUrl":"10.1134/S0016702924030030","url":null,"abstract":"<p>The partition of trace elements between minerals (olivine, orthopyroxene, clinopyroxene, and feldspars) and silicate melts is analyzed based on experimental data within broad <i>P</i>–<i>T</i> ranges (from 1 atm to 10 GPa and ∼1000–2000°C) and the compositions of melts (from ultramafic to ultrasilicic) and minerals. The dependences of the logarithmic partition coefficients (ln<i>D</i>_<i>i</i>) on <i>P</i>–<i>T</i> parameters and compositions are approximated by linear functions of 1/<i>T</i>, <i>P</i>/<i>T</i> (where <i>P</i> is pressure and <i>T</i> is temperature in K) and compositional parameters of the minerals and melts. The <i>D</i>_<i>i</i>/<i>D</i>_<i>j</i> ratios of a large number of pairs of elements are found out to be independent of experimental parameters and vary within narrow ranges. The parameters of the dependences of <i>D</i>_<i>i</i> on <i>P</i>–<i>T</i> and compositions are estimated by minimizing the squared deviations of model <i>D</i>_<i>i</i> and <i>D</i>_<i>i</i>/<i>D</i>_<i>j</i> values from experimental ones. The dependences thus derived make it possible to calculate <i>D</i>_<i>i</i> for numerous elements accurate to a factor of 1.2–2.0. As an illustrative example, a model is discussed for the derivation of mafic basaltic melts in mid-oceanic ridges at the melting of a peridotite source and crystallization of primary magmas under crustal parameters.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 3","pages":"221 - 233"},"PeriodicalIF":0.7,"publicationDate":"2024-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140567855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental Study of the ({text{Mo}}{{{text{O}}}_{{text{2}}}}{text{Cl}}_{{2left( {{text{aq}}} right)}}^{^circ }) Stability in Hydrothermal Solutions at 100–350°C and Saturated Vapor Pressure","authors":"A. A. Yakimenko,&nbsp;A. Yu. Bychkov","doi":"10.1134/S0016702924030066","DOIUrl":"10.1134/S0016702924030066","url":null,"abstract":"<div><p>The solubility of crystalline MoO₃ in HCl solutions with variable concentration was investigated at 100, 155, 200, 250, 300, 350°C and saturated vapor pressure. The results showed that the MoO₃ solubility increases with increasing HCl concentration. Using the OptimA program, the Gibbs energies of MoO₂Cl₂ complex have been determined. The stability constants of MoO₂Cl₂ are calculated according to the reaction:</p><div><div><span>$${text{Mo}}{{{text{O}}}_{{{text{3(c)}}}}} + 2{text{HC}}{{{text{l}}}_{{{text{(aq)}}}}} to {text{Mo}}{{{text{O}}}_{{text{2}}}}{text{Cl}}_{{2{text{(aq)}}}}^{^circ } + {{{text{H}}}_{{text{2}}}}{{{text{O}}}_{{{text{(l)}}}}}.$$</span></div></div><p>The <i>pK</i> values are 1.07 ± 0.29; 1.06 ± 0.49; 1.74 ± 0.71; 1.83 ± 0.47; 1.50 ± 0.28; 0.95 ± 0.57, respectively, at 100, 155, 200, 250, 300, 350°C (saturated vapor pressure).</p></div>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 3","pages":"267 - 273"},"PeriodicalIF":0.7,"publicationDate":"2024-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140567849","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Atacamite from the Paleofumaroles of Mount 1004, Tolbachik Volcano, Kamchatka: Thermodynamic Properties","authors":"Yu. D. Gritsenko,&nbsp;M. O. Bulakh,&nbsp;L. P. Ogorodova,&nbsp;M. F. Vigasina,&nbsp;L. V. Melchakova,&nbsp;D. A. Ksenofontov","doi":"10.1134/S001670292402006X","DOIUrl":"10.1134/S001670292402006X","url":null,"abstract":"<p>Atacamite, empirical formula (Cu_1.97Zn_0.01)Cl_0.94(OH)_3.02, from the paleofumaroles of the monogenic volcano of Mount 1004, Tolbachik, Kamchatka, Russia, has been studied by thermal and electron microprobe analyses, X-ray powder diffraction, IR and Raman spectroscopy, and Calvet microcalorimetry. The thermal decomposition of atacamite was studied using X-ray diffraction and IR spectroscopy. The enthalpy of formation from elements for atacamite of the theoretical composition Cu₂Cl(OH)₃ (−810.2 ± 7.7 kJ/mol) was determined by melt dissolution calorimetry, and the Gibbs energy of formation (−657.0 ± 7.7 kJ/mol) was calculated. The stability of atacamite in the Cu–O–Cl–H system was thermodynamically modeled based on the obtained data, and the boundaries of its stability field were calculated under conditions of high alkalinity and high acidity of the mineral-forming medium.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 2","pages":"172 - 183"},"PeriodicalIF":0.7,"publicationDate":"2024-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140567857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}