Geochemistry International最新文献

{"title":"Orogenic Gold Deposits of Northern Transbaikalia, Russia: Geology, Age, Sources, and Genesis","authors":"A. V. Chugaev","doi":"10.1134/S0016702924700484","DOIUrl":"10.1134/S0016702924700484","url":null,"abstract":"<p>The paper presents newly obtained and summarizes preexisting data of long-term geochronological and isotope studies of orogenic mesothermal gold deposits in the world’s largest Lena metallogenic province and reviews interpretations of their genesis. Geochronologic data indicate that the gold mineralization was formed during three ore-forming Paleozoic events. The early Late Ordovician–Early Silurian (450–430 Ma) event produced the abundant veinlet—disseminated gold–sulfide mineralization in Neoproterozoic carbonaceous terrigenous–carbonate rocks of the Baikal–Patom foldbelt (BPB). The mineralization was formed simultaneously with regional metamorphic processes. The rejuvenation of hydrothermal activity in the BPB resulted in gold-bearing quartz veins, which was produced in the Middle Carboniferous (340–330 Ma) in relation to postcollisional granitoid magmatism. The latest ore-forming event occurred in the Early Permian (290–280 Ma) and affected exclusively in Precambrian structures of the Baikal-Muya foldbelt (BMB). It was synchronous with the development of intraplate alkaline and subalkaline magmatism in the region. Newly obtained and preexisting isotopic-geochemical (⁸⁷Sr/⁸⁶Sr, ¹⁴³Nd/¹⁴⁴Nd, Pb–Pb, and δ³⁴S) data indicate that the mesothermal ore-forming systems of northern Transbaikalia were heterogeneous in their isotopic characteristics, which distinguishes them from the ore–magmatic (intrusion-related type) systems. Comparison of the Sr, Nd, and Pb isotopic composition of the ores and rocks, including magmatic rocks coeval with the gold mineralization, indicates that the Precambrian continental crust was the dominant source of mineral-forming components for the hydrothermal systems of the gold deposits. The contribution of the magmatic source to the genesis of the orogenic gold mineralization was limited and is identifiable only for the Early Permian ore-forming systems of the BMB, for which the input of metals from alkaline mafic melts was suggested.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 9","pages":"909 - 978"},"PeriodicalIF":0.7,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1134/S0016702924700484.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142519079","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":"Methane and Sulfide Sulfur in Water and Bottom Sediments of Watercourses of the Steppe Zone of the European Part of Russia","authors":"D. N. Gar’kusha,&nbsp;Yu. A. Fedorov,&nbsp;N. S. Tambieva","doi":"10.1134/S0016702924700459","DOIUrl":"10.1134/S0016702924700459","url":null,"abstract":"<p>The results of long-term studies of the conjugate distribution of methane (CH₄) and sulfide sulfur (S_sulfide) concentrations in the bottom sediments of watercourses of the steppe zone of the European part of Russia are analyzed. In addition to CH₄ and S_sulfide, Eh and pH values, humidity and density were determined in different sediment horizons; CH₄, dry residue, and pH values were determined in water. Concentrations of CH₄ in the watercourses vary from &lt;0.1 to 2007.0 μL/L (median 24.3 μL/L), with the largest number of values (72%) in the range 10.1–100.0 μL/L. The concentrations of CH₄ and S_sulfide in the bottom sediments of watercourses are quite high and vary, respectively, from &lt;0.01 to 51.0 µg/g of wet sediment (median 1.35 µg/g) and from &lt;0.001 to 4.50 mg/g of wet sediment (median 0.813 mg/g). Usually, the CH₄ and S_sulfide concentrations increase from the surface layer to the subsurface horizons, and then decrease. The difference between the distributions of S_sulfide and CH₄ is the more frequent occurrence of maximum concentrations of S_sulfide in less deep sediment horizons. Seasonal changes were recorded in the vertical distribution of CH₄ and S_sulfide not only in terms of their concentrations, but also in the position of maximum and minimum values. There is a weak positive correlation between the concentrations of CH₄ and S_sulfide, which indicates the synchronous formation of these gases in separate layers of sediments of the studied watercourses. The positive correlation established between the CH₄ concentrations in water and 0–2 cm layer of bottom sediments indicates that the sediments are an important source of CH₄ in water and its emission into the atmosphere.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 8","pages":"878 - 896"},"PeriodicalIF":0.7,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142414237","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":"Trends in Some Geochemical Parameters of Fine-Grained Clastic Rocks of Lower Riphean Sedimentary Sequences in the Northeastern and Central Parts of the Bashkirian Meganticlinorium, Southern Urals","authors":"A. V. Maslov","doi":"10.1134/S0016702924700411","DOIUrl":"10.1134/S0016702924700411","url":null,"abstract":"<p>The type sections of the Lower Riphean Burzyan Group (Ai, Satka, and Bakal formations) are located in the northeast part of the Bashkirian meganticlinorium. In its central and southern regions, the above formations are traditionally compared with the Bolshoi Inzer, Suran, and Yusha formations. Our studies whose results are discussed herein were centered on trends in the indicator ratios of trace elements in clay rocks of the six formations to obtain arguments in support of certain variants of their correlations. The trends in the average geochemical characteristics of clay rocks of the Burzyan Group in the northeastern and central + southern regions of the meganticlinorium, reflecting the composition of their parental rocks, were found out to be notably different. This does not necessarily indicate that individual correlations between the Burzyan Group rocks in various regions should be incorrect but rather highlights the necessity to revisit this problem.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 8","pages":"824 - 831"},"PeriodicalIF":0.7,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142413906","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":"Underwater Discharge of Fluids at the Bottom of Lake Baikal: Composition, Sources, and Migration Peculiarities within the MSU Structure","authors":"T. V. Pogodaeva,&nbsp;G. G. Akhmanov,&nbsp;N. A. Onishchuk,&nbsp;O. V. Shubenkova,&nbsp;A. V. Khabuev,&nbsp;O. M. Khlystov","doi":"10.1134/S0016702924700447","DOIUrl":"10.1134/S0016702924700447","url":null,"abstract":"<p>The paper presents geochemical study of bottom sediments from the MSU structure located on the large Gydratny Fault in the Central Basin of Lake Baikal at a depth of 1380 m. The first detailed data on the spatial variations in the qualitative and quantitative composition of the pore waters are presented. Pioneering data were obtained on Li, B, and Sr contents in the pore water of the sediments. It has been established that fluids are actively discharged within the MSU structure, and the main pathways of their near-surface migration are confined to the tops of hills of this structure on the downthrown fault block. The fluids are highly mineralized (up to 2900 mg/L), showing the highest mineralization ever found in Lake Baikal sediments. The waters are significantly enriched in Mg, Li, B, and Sr but depleted in K. The waters are thought to be generated by the processes of authigenic formation and illitization of smectite at depths of 1 to 2.5 km in the sedimentary sequence. The maximum values of concentration gradients are recorded in the pore waters of the sediments of the western hill, which may indicate a gradual westward shift of the center of the fluid seepage activity along the fault.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 8","pages":"864 - 877"},"PeriodicalIF":0.7,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142414238","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":"Dissolution of Ta–Nb and Nb Minerals in Granitoid Melts","authors":"V. Yu. Chevychelov,&nbsp;A. A. Viryus","doi":"10.1134/S001670292470040X","DOIUrl":"10.1134/S001670292470040X","url":null,"abstract":"<p>The effective solubilities (maximum contents) of Ta and Nb in model felsic lithium-fluoride melts of variable alkalinity and alumina content were experimentally determined at the dissolution of Ta–Nb and Nb minerals: pyrochlore, microlite, ilmenorutile, and ferrotapiolite at <i>T</i> = 650–850°C and <i>P</i> = 100 and 400 MPa. The Ta and Nb partitioning in the mineral-melt systems was also studied. When pyrochlore is dissolved in granitoid melts at <i>P</i> = 100 MPa and <i>T</i> = 650–850°C, the highest effective solubilities of Nb (0.7–1.8 wt %) are obtained in alkaline melt, and they significantly decrease (to 0.03–0.5 wt %) in subaluminous and peraluminous melts. A temperature increase increases the solubility (content) of Nb in the melt. Similar dependences were obtained for Ta solubility by dissolving microlite. In peraluminous granitoid melt, microlite remains stable, while pyrochlore becomes unstable. A pressure decrease from 400 to 100 MPa in alkaline and subaluminous melts was found out to not significantly affect on the dissolution of microlite and pyrochlore, whereas Ta and Nb contents in the peraluminous melt noticeably decrease. The dependences of Nb solubility and its partitioning between granitoid melts and ilmenorutile on the alkalinity–alumina content of the melt are similar to those for the dissolution of columbite and tantalite. The dependences obtained by dissolving ferrotapiolite, pyrochlore, and microlite differ from them.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 8","pages":"805 - 823"},"PeriodicalIF":0.7,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142413886","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":"Organic Matter in Hydrotherms of the Pauzhetka Field: Composition and Comparative Analysis with Other Sites","authors":"V. N. Kompanichenko,&nbsp;V. A. Poturay","doi":"10.1134/S0016702924700423","DOIUrl":"10.1134/S0016702924700423","url":null,"abstract":"<p>The composition of medium-volatile organic matter (OM) was studied in the steam–water mixture condensate (<b>SWC</b>) from deep production wells of the Pauzhetka geothermal field. Using solid-phase extraction and chromatography–mass spectrometry, 17 organic compounds, including 14 aliphatic and aromatic hydrocarbon (HC), were identified in the studied SWC. These components are strongly dominant in the Pauzhetka hydrothermal system and a number of other geothermal fields in Kamchatka, with their average contents amounting to higher than 60%. According to the specifics of the molecular weight distribution of the saturated HC, the high temperature of the steam–water mixture condensate (more than 108°C at the wellhead), and the absence of obviously biogenic components, these HC are thought to be produced by thermogenic processes: the transformation of organic remnants under the effect of high temperatures and pressures. The contents of the other compounds are much lower, and these components are mostly oxygen-containing compounds (ketones, aldehydes, and alcohols). Similarities between the spectra of organic compounds in the Pauzhetka and Uzon SWC may be at least partly explained by their extraction from volcanogenic–sedimentary layers containing buried organic matter.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 8","pages":"832 - 843"},"PeriodicalIF":0.7,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142413913","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":"Biogeochemistry of Peat Deposits of the Holocene Section of the Vydrino Bog (Southern Baikal Region)","authors":"A. E. Maltsev,&nbsp;V. A. Bobrov,&nbsp;G. A. Leonova,&nbsp;Y. I. Preis,&nbsp;M. A. Klimin,&nbsp;V. A. Bychinsky","doi":"10.1134/S0016702924700435","DOIUrl":"10.1134/S0016702924700435","url":null,"abstract":"<p>The paper reports the detailed studies of drilling cores from peat deposits of the Vydrino bog with a thickness of 4.4 m and an age of 13 100 cal. years. The peat is composed of fen, transitional, and raised types. The early-diagenetic transformations of peat sediments are considered, and the distribution of elements, the formation of authigenic minerals, and the chemical composition of bog waters are studied. The destruction of organic matter begins from the upper intervals of peat at the early diagenetics stage. Pyrograms do not have clearly defined high-temperature peaks, “rudiments” of the macromolecular structure of kerogen, which indicates a low degree of transformation of peat organic matter. The high abundance of organotrophic, ammonifying, nitrifying, and phosphate-mobilizing microorganisms, and the low abundance of Fe- and Mn-oxidizing microorganisms, and sulfate-reducing bacteria are revealed. The presence of organotrophic microorganisms throughout the section indicates that the biogeochemical processes of the carbon cycle span the entire peat sequence. The low S(II) content indicates the low intensity of sulfate reduction. The fen peat is characterized by the high contents of Si, Al, Fe, Ca, Sr, Ba, Zr, La and anomalous contents of Cu, Zn, which is caused by the peatland formation under conditions of rich mineral nutrition. The ash part of the transitional peat demonstrates a decrease in the contents of Si, Fe, Sr, Br, K Si, Ca, Ba, Cu, Zn and La, which reflects the gradual weakening of the connection of the peat deposit with the underlying rocks. The near-surface horizon of raised peat is characterized by an increase in the contents of K, Mn, Zn, Hg, Pb and As, which is accompanied by an increase in atmospheric dust and anthropogenic impact on the bog ecosystem in the 20th and 21st centuries. The bog waters of the fen peat are characterized by the high contents of the main ions, Al, Fe, Mn, Sr, while the transitional peat shows a decrease in DOC, <span>({text{SO}}_{4}^{{2 - }})</span>, <span>({text{HCO}}_{3}^{ - })</span>, Al, Fe, Ni, Ca, Mg. The oligotrophic stage peat deposit layer is characterized by the development of Fe oxides and hydroxides, the presence of vivianite is noted for transitional peats, and the eutrophic stage layer includes rhodochrosite and sulfides of Fe, Cu, and Zn.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 8","pages":"844 - 863"},"PeriodicalIF":0.7,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142414115","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":"Trace Element Composition of Discordant Zircon as a Reflection of the Fluid Regime of Paleoproterozoic Granulite Metamorphism (Khapchan Terrane, Anabar Shield)","authors":"S. G. Skublov,&nbsp;N. I. Gusev,&nbsp;L. I. Salimgaraeva,&nbsp;L. Yu. Romanova","doi":"10.1134/S0016702924700393","DOIUrl":"10.1134/S0016702924700393","url":null,"abstract":"<p>New data on the U–Pb age (SHRIMP-II) and trace element composition (SIMS) of zircon from gneisses of the Khapchan Group of the Khapchan terrane of the Anabar Shield are presented. Zircon grains contain relicts of magmatic zircon, the protolith and source areas of which are difficult to specify. The only zircon in this group with the least altered core preserved the ²⁰⁷Pb/²⁰⁶Pb protolith age of 1971 ± 19 Ma. During granulite metamorphism, the zircon was subjected to the impact of fluid enriched in incompatible elements. The disurbances affected both the U–Pb isotope system (zircon age was “reset” at metamorphic age of 1920–1930 Ma) and composition of zircon, magmatic cores of which were significantly recrystallized in a solid state or dissolved by fluid up to the practically complete disappearance of primary zircon. In both the cases, zircon was sharply enriched in incompatible elements (Ca, Ti, Pb, Sr, Ba, and some others) owing to fluid effect, while preserved cores seemed to be rimmed by a new zircon population (CL-black). The REE distribution patterns in the recrystallized cores acquired a “bird’s wing” profile atypical for zircon. When the fluid lost its reactivity, the main part of the zircon grain crystallized, typical of granulite zircon. This zircon population is less enriched in incompatible element than the cores are. The horizontal pattern of HREE distribution is consistently repeated, which indicates the co-crystallization of zircon and garnet. The estimated crystallization temperature of the main part of zircon varies in a narrow range of 800–830°C. All zircon domains in the Wetherill concordia diagram form a single trend with a zero lower intercept and an upper intercept confirmed by concordant cluster with an age around 1920–1930 Ma. This value corresponds to the age of regional Paleoproterozoic granulite metamorphism. A unique feature of zircon from the Khapchan gneisses is that its cores did not retain the age marks of the protolith, but were completely reset during metamorphism both in terms of the U-Pb system and the trace element composition, which can be explained by the extremely high intensity of fluid impact during the granulite facies metamorphism superimposed on the rocks of the Khapchan terrane of the Anabar Shield.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 8","pages":"793 - 804"},"PeriodicalIF":0.7,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142414242","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":"Cryolite as a Reference Mineral of Rare Metal Mineralization: An Experimental Study","authors":"A. A. Rusak,&nbsp;T. I. Shchekina,&nbsp;N. G. Zinovieva,&nbsp;A. Y. Bychkov,&nbsp;O. A. Lukanin","doi":"10.1134/S0016702924700332","DOIUrl":"10.1134/S0016702924700332","url":null,"abstract":"<p>Phase relations and the distributions of rare earth elements (REE), Sc, Y, and Li between aluminofluoride and aluminosilicate melts in the model granite system Si–Al–Na–K–Li–F–O–H were experimentally studied at 700°C, 1 and 2 kbar, and water contents of 3 to 50 wt %. Our original and available literature experimental data on phase relations in the granite system saturated with water and fluorine and containing trace elements are compared with the mineral assemblages of rare-metal cryolite-bearing granites from the Zashikhinsky, Katugin, and Ulug-Tanzek deposits in eastern Siberia. Liquid immiscibility between granite and salt aluminofluoride melts, which occurs at high contents of fluorine and lithium in the system, is proved to facilitate the accumulation of rare elements in salt cryolite-like melts. At a temperature of 700°C and pressures of 1 and 2 kbar, aluminofluoride melt in the granite system crystallizes and forms cryolite. Fluorine-bearing minerals of trace and rare earth elements, such as pyrochlore and gagarinite, occur at these deposits in association with cryolite and lithium micas. Comparison of experimental data and natural observations provides arguments in support of the hypothesis that liquid immiscibility should play an important role in the formation of cryolite. Cryolite is thought to be able to serve as a reference mineral for rare metal-rare earth mineralization in granites with high lithium and fluorine content.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 7","pages":"714 - 732"},"PeriodicalIF":0.7,"publicationDate":"2024-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208341","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":"EPR Spectroscopic and Calorimetric Study of Minerals of the Amblygonite–Montebrasite Series from Rare-Metal Pegmatite of the Voron’i Tundras (Kola Peninsula) and Sangilen Highlands (Tuva)","authors":"S. V. Vyatkin,&nbsp;Yu. D. Gritsenko,&nbsp;L. P. Ogorodova,&nbsp;M. F. Vigasina,&nbsp;D. A. Ksenofontov,&nbsp;L. V. Melchakova","doi":"10.1134/S0016702924700344","DOIUrl":"10.1134/S0016702924700344","url":null,"abstract":"<p>The paper reports the first comprehensive physicochemical study of minerals of the amblygonite LiAlPO₄F–montebrasite LiAlPO₄(OH) series. An EPR spectroscopic and calorimetric study of montebrasite LiAlPO₄(OH)_0.9F_0.1 from the Shuk-Byul rare-metal granite pegmatites (Sangilen Highlands, Tuva) and amblygonite LiAlPO₄F_0.5(OH)_0.5 from pegmatites of the Voron’i Tundras (Kola Peninsula) was carried out. Using the EPR method, the radiation-sensitive paramagnetic O^– centers were discovered. They were formed without participation of impurity elements in the regular sites of crystal lattice. The possibility use of minerals of the amblygonite–montebrasite series for EPR geochronometry has been demonstrated for the first time. Using the method of high-temperature melt dissolution calorimetry on a Tian-Calvét microcalorimeter, the enthalpies of formation from elements <span>({{Delta }_{f}}H_{{{text{el}}}}^{0})</span> (298.15 K) = –2326.3 ± 2.2 kJ/mol for montebrasite with the composition LiAl(PO₄)(OH)_0.9F_0.1 and for amblygonite with the composition LiAl(PO₄)F_0.5(OH)_0.5 (‒2347.9 ± 3.1 kJ/mol) are obtained; and the values of this parameter are calculated for the end members with an ideal composition of the series: for montebrasite (–2315.5 ± 2.2 kJ/mol) and for amblygonite (–2401.6 ± 3.1 kJ/mol). The values of the standard entropy <i>S</i>⁰ (298.15 K) and the Gibbs energy of formation <span>({{Delta }_{f}}G_{{{text{el}}}}^{0})</span> (298.15 K) for intermediate and end members of the amblygonite–montebrasite series are estimated.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 7","pages":"748 - 759"},"PeriodicalIF":0.7,"publicationDate":"2024-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208342","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}