Geochemistry International最新文献

{"title":"Formation Conditions of Gold Mineralization in the Spokoininsky Ore Cluster, Aldan Shield, Russia","authors":"V. N. Kardashevskaia,&nbsp;L. A. Kondratieva,&nbsp;E. O. Shaparenko,&nbsp;G. S. Anisimova","doi":"10.1134/S0016702924700824","DOIUrl":"10.1134/S0016702924700824","url":null,"abstract":"<p>The paper presents the first data on individual fluid inclusions hosted in quartz in the ores of three types (polysulfide, gold–silver–telluride, and gold–bismuth) of the Spokoininsky ore cluster with gold ore mineralization. The three ore types show differences in the physicochemical parameters and composition of their fluids. The fluid of the Spokoininsky cluster polysulfide ores are characterized by a relatively low initial temperature (180‒350°C), a higher CO₂ density (0.27‒0.71 g/cm³), and a higher fluid pressure (0.7‒1 kbar) compared to the fluids that formed the gold–silver–telluride ores (temperature 200–260°C, CO₂ density 0.28–0.56 g/cm³, pressure 0.7 kbar). The dominant salts in the fluids of polysulfide ores are Na and Mg chlorides, whereas the mineral-forming fluids of the gold–silver–telluride ores are simpler saline aqueous fluids containing Na chlorides. The fluids that formed the polysulfide ores have a H₂O–CO₂–N₂ composition, whereas the fluid of the gold–silver–telluride ores is mostly of H₂O–CO₂ composition. The gold–bismuth ores in the Mayskoe ore field were formed by H₂O–CO₂-bearing fluids with a salinity concentration of 4.0‒6.4 wt %-equiv. NaCl, a CO₂ density of 0.56‒0.61 g/cm³, at a temperature of 280‒335°C and a pressure of 0.7 kbar. The data led us to conclude that the ore-forming fluid of the Spokoininsky ore cluster was similar to the fluids of orogenic gold deposits.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"63 1","pages":"63 - 76"},"PeriodicalIF":0.7,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143489584","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":"Differentiation Features of Alkaline Rocks in Ilmen Miaskite Massif: New Mineralogical and Geochemical Data","authors":"E. S. Sorokina,&nbsp;E. V. Medvedeva,&nbsp;A. B. Nemov,&nbsp;M. A. Rassomakhin,&nbsp;L. N. Kogarko","doi":"10.1134/S0016702924700782","DOIUrl":"10.1134/S0016702924700782","url":null,"abstract":"<p>The Ilmen miaskite massif in the Southern Urals remains largely understudied from the mineralogical and geochemical standpoints, and theories of its formation are still debatable. The paper presents the first data on the mineral associations of the miaskite varieties and REE-rich minerals. Microchemical studies determined that the pyroxene–amphibole miaskites are the most promising rock variety for REE mineralization (REE content at ca. 1500 ppm). These rocks show clearly discernible positive Nb anomalies combined with a negative Pb anomaly. The temperatures of feldspar exsolution indicate their following formation sequence within the miaskite varieties (from higher temperature to lower temperature ones): pyroxene–amphibole miaskite → garnet–amphibole miaskite → amphibole miaskite → biotite miaskite</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"63 1","pages":"51 - 62"},"PeriodicalIF":0.7,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143489470","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":"Actinides in the Soil Chronosequence of the Amur River Floodplain","authors":"A. V. Martynov","doi":"10.1134/S0016702924700848","DOIUrl":"10.1134/S0016702924700848","url":null,"abstract":"<p>For the first time, a study was conducted at the Russian Far East to assess the rate of accumulation of gross and mobile forms of actinides (U and Th) in a 5000-year-old soil chronosequence embedded within the floodplain of the middle reaches of the Amur River. The relationships between actinides and the properties of alluvial and residual alluvial soils are characterized using regression models. It was found that during the evolution, the content of the gross form of actinides in the soils of the automorphic series increased from 1 to 2 mg/kg for U and from 4 to 10 mg/kg for Th. In the soils of the hydromorphic series, the increase over a shorter time period (2600 years) was from 1 to 3 mg/kg for U and from 4 to 12 mg/kg for Th. The content of the mobile U form in automorphic and hydromorphic soils increased on average from 0.1 to 0.4 mg/kg, and that of Th, from 0.02 to 0.2 mg/kg. In the automorphic soils, the accumulation of U is observed as long as the floodplain is regularly flooded, while Th continues to accumulate even after the floodplain leaves the flood zone. In the hydromorphic soils, the accumulation of actinides continues over the entire chronological range. The results obtained show that the main soil properties determining the accumulation of actinides in soils are the content of clay minerals and iron oxides. The intake of actinides into the soils of the Amur River floodplain occurs mainly due to the weathering of melanocratic granitoid minerals in the alluvium. The mobilization of actinides is affected by pH in automorphic soils and Eh in hydromorphic soils.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"63 1","pages":"96 - 109"},"PeriodicalIF":0.7,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143489412","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":"Low Pb Isotopic Variations in the Extensive Chatkal–Kurama Ore Province, Middle Tien Shan, and Sources of the Large Scale Au, Ag, and Multimetal Mineralization: Evidence from High-Precision Pb Isotope Data","authors":"I. V. Chernyshev,&nbsp;A. V. Chugaev,&nbsp;V. A. Kovalenker","doi":"10.1134/S0016702924700800","DOIUrl":"10.1134/S0016702924700800","url":null,"abstract":"<p>The Chatkal–Kurama region in the central Tien Shan is a superlarge porphyry–epithermal gold ore province. The paleovolcanic area hosts world-class Au, Ag, and base-metal deposits (Kalmakyr, Kochbulak, Kanimansur, etc.). Using the high-precision (±0.02%) MC-ICP-MS method of lead isotope analysis, we studied a collection of 63 ore samples (47 of them are galena) from 18 deposits, which represent all types of Au–Ag, Au–Ag–base metal, and Cu–Au–Mo deposits known in the region. The same method was applied to study 21 samples of igneous rocks from this region, for which lead isotope composition was determined in monomineralic feldspar separates. The Pb isotope ratios ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb, and ²⁰⁸Pb/²⁰⁴Pb from the ore deposits vary within narrow ranges: 17.9885–18.1598, 15.5897–15.6412, and 38.0385–38.2380, respectively. These variations in relative terms are 0.94, 0.33, and 0.52%, respectively, and are among the smallest among ore provinces around the world. An even higher (two to five times) degree of homogeneity is typical of the Pb isotopic composition at individual deposits in the region. The lead isotope composition of deposits and ore fields in the Chatkal–Kurama region does not depend on their mineralogical and geochemical features but is instead controlled by the geological settings of the deposits. The discovered close similarity between ore deposits and Late Paleozoic granitoids in Pb isotope composition provides evidence in support of the hypothesis that genetic connection of the large-scale Au, Ag, and base-metal is genetically related to magmatism, which developed in a subduction environment. An interesting fact is that the Pb isotope composition is identical at the Kalmakyr Cu–Au–Mo porphyry deposit and the neighboring Akturpak Au epithermal deposit, which provides evidence that metals for these deposits (which are different in composition and were formed under different <i>P</i>–<i>T</i> parameters) were derived from a common source. The isotope composition and its evolutionary model characteristics according to the Stacey–Kramers model indicate (in agreement with the data on Sr and Nd) that Pb of the rocks and deposits in the region is mid-crustal, typical of island-arc regions of the Andean type. The mantle component of the source of the regional ore-bearing magmas was the material of mantle lithosphere and oceanic crust that was partially melted in a subduction environment in the mantle wedge zone. The ratio Th/U = 3.86–3.99, which is higher than the average crustal value, indicates a significant contribution of Precambrian basement rocks of the Chatkal–Kurama terrane to the petrogenesis of the ore-bearing magmas.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"63 1","pages":"1 - 29"},"PeriodicalIF":0.7,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143489582","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":"The Archean Age of Granite-Gneiss Complexes from the Kama–Vyatka Zone (the Volga-Ural Segment, East European Craton)","authors":"M. O. Anosova,&nbsp;O. V. Astrakhantsev,&nbsp;A. V. Postnikov,&nbsp;A. A. Fedotova,&nbsp;T. I. Kirnozova,&nbsp;M. M. Fugzan,&nbsp;I. A. Sabirov","doi":"10.1134/S0016702924700794","DOIUrl":"10.1134/S0016702924700794","url":null,"abstract":"<p>The formation history of granulite complexes is fundamental significance for understanding the growth of early continental crust. The work presents the results of an isotope-geochronological study of rock samples from the main lithotectonic complexes of the Kama–Vyatka zone (the Volga–Ural segment of the East European Craton)—enderbites of the Otradnenskaya Group and quartz diorites of the Tanaisky plagiogranitoid massif. The model ages of quartz diorites of the Tanaisky plagiogranitoid massif and enderbites of the Otradnenskaya Groups calculated from Sm–Nd data are 3.2 and 3.0 Ga, respectively. Zircons from the quartz diorites of the Tanaisky plagiogranitoid massif and the enderbites of the Otradnenskaya Group were dated by U–Pb LA-ICP-MS method. Zircon from quartz diorites yielded the Archean age of protolith of the plagiogranitoids of the Tanaisky Massif. This time interval of 3.04–2.98 Ga marks the stage of the oldest granulite metamorphism immediately following the magmatic event. Zircons from weakly gneissose enderbites of the Otradnenskaya Group is subdivided into two age groups: 3.0–2.8 and 2.750–2.60 Ga. Based on the morphology, internal structure of the crystals, and their isotope-geochemical characteristics (Th and U contents, Th/U ratio), each of the indicated age groups includes several zircon generations. Within a time interval of 3.0–2.8 Ga, the identified zircon generations record the following events: the formation of primary enderbites, local partial melting under the granulite-facies conditions, and retrograde metamorphism under transitional granulite–amphibolite facies. With allowance for the model age of the enderbites, the Otradnenskaya Group of the Kama–Vyatka zone of the Volga–Ural segment was dated for the first time at 3.0 ± 0.1 Ga. In the time interval of 2.75–2.60 Ga, zircon from weakly gneissose enderbites records the peak granulite metamorphism, which spanned the entire Volga-Ural segment, and subsequent retrograde metamorphism accompanying by the input of hydrous fluid and temperature decrease.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"63 1","pages":"30 - 50"},"PeriodicalIF":0.7,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143489583","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":"Chemical Composition, Mineralogy, and Physical Properties of the Moon’s Mantle: A Review","authors":"O. L. Kuskov,&nbsp;E. V. Kronrod,&nbsp;V. A. Kronrod","doi":"10.1134/S0016702924700733","DOIUrl":"10.1134/S0016702924700733","url":null,"abstract":"&lt;p&gt;The problem of the internal structure of the Moon plays a special role in understanding its geochemistry and geophysics. The principal sources of information about the chemical composition and physical state of the deep interior are seismic experiments of the Apollo expeditions, gravity data from the GRAIL mission, and geochemical and isotopic studies of lunar samples. Despite the high degree of similarity of terrestrial and lunar matter in the isotopic composition of several elements, the problem of the similarity and/or difference in the major-component composition of the silicate shells of the Earth and its satellite remains unresolved. This review paper summarizes and critically analyzes information on the composition and structure of the Moon, examines the main contradictions between geochemical and geophysical classes models for the mantle structure, both within each class and between the classes, related to the estimation of the abundance of Fe, Mg, Si, Al, and Ca oxides, and analyzes bulk silicate Moon (BSM) models. The paper describes the principles of the approach to modeling the internal structure of a planetary body, based on the joint inversion of an integrated set of selenophysical, seismic, and geochemical parameters combined with calculations of phase equilibria and physical properties. Two new classes of the chemical composition of the Moon enriched in silica (∼50% SiO&lt;sub&gt;2&lt;/sub&gt;) and ferrous iron (11–13% FeO, Mg# 79–81) relative to the bulk composition of the silicate component of the Earth (BSE) are discussed: (i) models E with terrestrial concentrations of CaO and Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; (Earth-like models) and (ii) models M with higher contents of refractory oxides (Moon-like models), which determine the features of the mineralogical and seismic structure of the lunar interior. A probabilistic distribution of geochemical (oxide concentrations) and geophysical (&lt;i&gt;P&lt;/i&gt;-, &lt;i&gt;S&lt;/i&gt;-wave velocities and density) parameters in the four-layer lunar mantle within the range of permissible selenotherms was obtained. Systematic differences are revealed between contents of major oxides in the silicate shells of the Earth and the Moon. Calculations were carried out for the mineral composition, &lt;i&gt;P&lt;/i&gt;-, &lt;i&gt;S&lt;/i&gt;-wave velocities, and density of the E/M models, and two classes of conceptual geochemical models: LPUM (Lunar Primitive Upper Mantle) and TWM (Taylor Whole Moon) with Earth’s silica content (∼45 wt % SiO&lt;sub&gt;2&lt;/sub&gt;) and different FeO and Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; contents. Arguments are presented in support of the SiO&lt;sub&gt;2&lt;/sub&gt;- and FeO-enriched (olivine pyroxenite) lunar mantle, which has no genetic similarity with Earth’s pyrolitic mantle, as a geochemical consequence of the inversion of geophysical parameters and determined by cosmochemical conditions and the mechanism that formed the Moon. The dominant mineral of the lunar upper mantle is high-magnesium orthopyroxene with a low calcium content (rather than olivi","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 12","pages":"1227 - 1290"},"PeriodicalIF":0.7,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1134/S0016702924700733.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143109415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Shaka Ridge (South Atlantic)—a Remnant of Continental Crust?","authors":"N. M. Sushchevskaya,&nbsp;G. L. Leitchenkov,&nbsp;B. V. Belyatsky,&nbsp;D. A. Agapitova","doi":"10.1134/S0016702924700757","DOIUrl":"10.1134/S0016702924700757","url":null,"abstract":"<p>As a result of a study of igneous rocks of the basalt - andesite series, dredged on the Shaka Ridge in the South Atlantic, it was found that they differ from the basalts of mid-ocean ridges and ocean islands, and have an age of 183.8 ± 2.2 Ma, comparable to the time of manifestation of the Karoo-Maud mantle plume in central Gondwana. Geochemical and Sr–Nd–Pb isotopic features of the studied igneous rocks show their similarity with the Jurassic mafic complexes of the Ferrar province in Antarctica and the Falkland Islands, formed during the intrusion of the Karoo-Maud plume and under the influence of paleo-Pacific subduction. However the supply of ice rafted debris into the study area due to ice transportation is considered unlikely. Based on the all data obtained, it was concluded that the Shaka Ridge is a continental block that was moved during the opening of the South Atlantic in the Early Cretaceous-Early Miocene from the continental margin of Africa along an extended transform fault into the present Bouvet triple junction area.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 12","pages":"1332 - 1351"},"PeriodicalIF":0.7,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1134/S0016702924700757.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143109280","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Kinetics of Individual C1–C5 Hydrocarbons Formation of Domanik Shale in Hydrothermal Experiments","authors":"D. A. Bushnev,&nbsp;N. S. Burdelnaya,&nbsp;A. A. Ilchenko,&nbsp;Ya. D. Sennikova,&nbsp;D. V. Kuzmin","doi":"10.1134/S0016702924700769","DOIUrl":"10.1134/S0016702924700769","url":null,"abstract":"<p>Twelve hydrothermal autoclave experiments were conducted with Domanik oil shale from the Ukhta region (Chut River) at temperatures of 250–375°C and run duration of 24 h (6 experiments), 72 h (5 experiments), and 48 h (1 experiment). The composition of hydrocarbon gases C₁–C₅ was studied for each experiment and quantitative data on their yields were obtained. Based on these data, the distributions of generation potential of individual gaseous hydrocarbons by activation energy were established under hydrothermal experimental conditions. The character of the kinetic spectra of individual alkanes C₂–C₅ is virtually identical; their main narrow maximum corresponds to <i>E</i>_a 55 kcal/mol with an Arrhenius factor of 1 × 10¹⁴ s^–1. The distribution of the methane generation potential by activation energies is distinguished by the fact that a significant part of its generation potential falls within the region of activation energies of 60–70 kcal/mol and by the uncertainty of the distribution character in this region.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 12","pages":"1352 - 1357"},"PeriodicalIF":0.7,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143109289","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":"The Formation of K-Cymrite in Subduction Zones and Its Potential for Transport of Potassium, Water, and Nitrogen into the Mantle","authors":"A. G. Sokol,&nbsp;A. V. Korsakov,&nbsp;A. N. Kruk","doi":"10.1134/S0016702924700745","DOIUrl":"10.1134/S0016702924700745","url":null,"abstract":"<p>The conditions of the formation of K-cymrite in volatile-rich pelite and partially devolatilized mica quartz–muscovite–chlorite schist were experimentally investigated at pressures of 5.5, 6.3, and 7.8 GPa and temperatures ranging from 900 to 1090°C corresponding to hot subduction geotherm. Experimental samples at these <i>P–T</i> conditions formed assemblage of solid phases (<i>Grt + Coe + Phe + Cpx + Ky</i>, with accessory <i>Po + Ru + Zrn ± Mnz</i>) and water-enriched supercritical fluid–melt. Analysis of the obtained data indicates that the stability of phengite and its potential replacement by K-cymrite depends on the <i>P–T</i> conditions and the amount of volatiles in the metasediment. In samples of volatile-rich pelite and mica schist at 5.5 GPa and 900°C, as well as at 6.3 GPa and 1000°C, phengite remains stable in equilibrium with 3–13 wt % of the fluid–melt. With increasing pressure up to 7.8 GPa and temperature up to 1090°C, the fraction of supercritical fluid–melt in pelite reaches 20 wt %, while phengite disappears. Only 5 wt % supercritical fluid–melt are formed in the schist at 7.8 GPa and 1070°C, while most part of phengite is preserved. For the first time, phase assemblage with phengite and K-cymrite (±kokchetavite) was obtained in the pelite and schist samples at 7.8 GPa and 1070°C. The assemblage was identified using Raman mapping. At stepwise devolatilization (with removal of fluid–melt portion forming in equilibrium with volatile-bearing minerals that are stable at <i>P–T</i> conditions of experiments), phengite has been preserved up to 7.8 GPa and 1090°C, but K-cymrite is not formed in the absence of fluid–melt. It was concluded that the most effective transport of volatiles (first of all, water) in the metasediment to depths over 240 km may occur during its partial and early (before the formation of supercritical fluid–melt) devolatilization. In this case, almost all phengite may reach depths of 240 km during metasediment subduction and then transform into water-bearing K-cymrite, or, in the presence of nitrogen in the metasediment, into nitrogen-bearing K-cymrite, thus facilitating the further transport of LILE (large-ion lithophile elements), water, and nitrogen. However, the formation of a significant portion of supercritical fluid–melt leads to the complete dissolution of phengite with increasing <i>P–T</i> conditions, making further transport of LILE, water, and nitrogen impossible. During deep multi-stage devolatilization, phengite remains stable up to depths of 240 km; however, during further subduction, it likely transforms into an anhydrous K-hollandite (KAlSi₃O₈).</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 12","pages":"1322 - 1331"},"PeriodicalIF":0.7,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1134/S0016702924700745.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143109281","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exsolution in the Au–Au3Cu Region and Correction of the Au–Ag–Cu Phase Diagram","authors":"S. A. Onishchenko,&nbsp;K. G. Parkhacheva,&nbsp;Yu. V. Glukhov,&nbsp;S. K. Kuznetsov,&nbsp;N. Yu. Nikulova,&nbsp;E. M. Tropnikov","doi":"10.1134/S0016702924700642","DOIUrl":"10.1134/S0016702924700642","url":null,"abstract":"<p>The phase composition of native gold was examined in an insufficiently studied part of the Au–Ag–Cu system in the range between pure gold and Au₃Cu. In this region, a miscibility gap has been established for the Au–Ag–Cu solid solution, which is decomposed into Au–Ag–Cu and Au₃Cu phases. These results in combinations with previously obtained and literature data made it possible to construct a complete phase diagram of the Au–Ag–Cu system in the gold-rich region for low (about 100°C) temperature. The diagram demonstrates the field of a homogeneous Au–Ag–Cu solid solution, and two-phase fields (Au₃Cu and Au–Ag–Cu solid solution) and (AuCu and Au–Ag–Cu solid solution), which are separated by a three-phase field (Au₃Cu, AuCu, and Au–Ag–Cu solid solution).</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 11","pages":"1174 - 1183"},"PeriodicalIF":0.7,"publicationDate":"2024-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1134/S0016702924700642.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142890441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}