Geochemistry International最新文献

{"title":"Characteristics and Formation Mechanism of Geothermal Resources in Tectonically Active Regions: A Case Study of the Red River Fault in Western Yunnan Province, China","authors":"Longfei Xu,&nbsp;Shijing Chen,&nbsp;Jinchuan Zhang,&nbsp;Yishan Cheng,&nbsp;Qianchao Li,&nbsp;Lei Chen,&nbsp;Yuhang Sun,&nbsp;Hui Tan","doi":"10.1134/S0016702924700605","DOIUrl":"10.1134/S0016702924700605","url":null,"abstract":"<p>Geothermal Resource as a kind of renewable energy is widely distributed in tectonically active regions. Using hot springs along the Red River fault zone as an example, this study attempts to analyze the recharge source, recharge elevation, reservoir temperature, circulation depth, mixing of cold groundwater, and heat source through ions, stable hydrogen and oxygen isotopes, and data in previous studies to determine the characteristics and formation mechanism of geothermal resources in tectonically active regions. The findings show that whereas the non-thermal groundwater is abundant in <span>({text{HCO}}_{3}^{ - })</span>–Ca²⁺, the hot springs in the Red River Fault are predominantly of the <span>({text{HCO}}_{3}^{ - })</span>–Na⁺ type. The stable hydrogen and oxygen isotopes indicate that the geothermal water is derived from local meteoric precipitation, with a positive excursion in the oxygen isotope indicating that the geothermal water has undergone the strong water-rock interaction under high reservoir temperature. The recharge area is located in the mountainous regions on both sides of the Red River Fault, with recharge elevations ranging from 2252 and 3482 m. The reservoir temperature varies from 67.4 to 173.42°C calculated by the SiO₂ geothermometer, and the associated circulation depth is between 1601.18–5134.12 m. Furthermore, the data of previous studies suggest that the primary heat sources in the study area are mantle-derived heat, crust-derived heat, and radioactive heat, while the composition ratio of various heat sources is different from north to south because of the influence of structural development. The primary determinants of geothermal resources in tectonically active regions are the composition of the heat source and the scale and number of large faults, which in turn affect the temperature of geothermal resources.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 13","pages":"1433 - 1449"},"PeriodicalIF":0.7,"publicationDate":"2024-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143108486","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":"Noble Gases, Carbon and Nitrogen Isotopes in Different Lithologies of Pesyanoe: Irradiation History and Impact Processes on the Aubrite Parent Body","authors":"A. I. Buikin,&nbsp;A. B. Verchovsky,&nbsp;J. Hopp,&nbsp;C. A. Lorenz,&nbsp;E. V. Korochantseva,&nbsp;M. Trieloff,&nbsp;U. Ott","doi":"10.1134/S0016702924700617","DOIUrl":"10.1134/S0016702924700617","url":null,"abstract":"<p>We present the results of stepwise crushing and combustion analyses for noble gases, carbon and nitrogen in Pesyanoe aubrite pyroxene lithologies, composed of grey (Px-G) and light (Px-B) enstatites differing in the degree of impact processing and the number of inclusions. Our study identifies three main noble gas endmembers in Pesyanoe: a cosmogenic component, radiogenic ⁴⁰Ar, and an endmember representing a mixture of solar wind and Q components in variable proportions. Based on petrographic and noble gas data we argue that these gases accumulated in the material during its regolith history and were later redistributed into gas inclusions/voids as the result of an impact event. During impact metamorphism, Px-G acquired its grey color and multiple gas inclusions were formed within it, more than in case of Px-B. Our study demonstrates for the first time: (1) The host phase of gases trapped during shock metamorphism are grains of rock-forming minerals, in particular Px-G, due to the formation of a large number of cracks in the direction of cleavage during brittle deformation, (2) The gas capture is associated not with the final stage of the formation of consolidated fragmental breccia, at which lithification of the fragments occurred, but with one of the intermediate impact events. High amounts of trapped and cosmogenic noble gases are released during the stepwise crushing—significantly higher than in case of any other studied aubrite. Some unusually high ³⁶Ar/¹³²Xe ratios (up to 54 780 versus 22 705 in the solar wind) were discovered during crushing of Px-G. Our preferable explanation of this phenomenon is a specific superposition of noble gas elemental fractionation processes related to the impact cratering of the Pesyanoe parent body. The carbon isotopic composition (δ¹³C = –21.2 ± 0.2‰, 1σ) is slightly heavier than that of the Bustee aubrite carbon. The combined use of different extraction methods made it possible to determine that the solar type and indigenous (δ¹⁵N_indig = –0.1 ± 3.2‰, 1σ) nitrogen components are located in the gas inclusions, whereas the extraneous nitrogen component (~+45‰) is chemically bound. The large cosmic ray exposure age variations (44 and 55 Ma in case of Px-G and Px-B, respectively) and the heterogeneous distribution of solar-type gases in Pesyanoe aubrite point to a diverse irradiation history of the material before breccia formation. Alternatively/additionally, cosmogenic gases (as well as solar and primordial) in Px-G may have became lost and/or partly redistributed into gas inclusions as a result of the impact event.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 12","pages":"1291 - 1321"},"PeriodicalIF":0.7,"publicationDate":"2024-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1134/S0016702924700617.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143108484","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":"Geochemical and Provenance Studies of Trans-Himalayan Lake Sediments, Ladakh, India: Their Relationship with Catchment Geology, Geomorphology and Constraint with Different Tectonic Settings","authors":"Shabir A. Mir,&nbsp;Mohammad M. Najar,&nbsp;Ajay Kumar,&nbsp;Rohit Sharma","doi":"10.1134/S0016702924700587","DOIUrl":"10.1134/S0016702924700587","url":null,"abstract":"<p>The Kyun Tso lakes are located in the climate-sensitive and tectonically active area in Ladakh, India. The terrain is an example of deciphering tectonism and provenance studies. Kyun Tso consists of twin lakes Chilling Tso and Ryul Tso. The lakes are located near the Nidar ophiolite suite at an altitude of 5500 m amsl (above mean sea level) in the arid Trans Himalayan Region. Rocks of augen gneiss or para-gneiss of Tsomoriri Gneissic Complex, graphitic schist of Rupshu Formation, metavolcanics of Kuling Lilang Formation, ultrabasic rocks of Sangeluma Formation and alluvium of Quarternary deposits from Paleo-Proterozoic to recent age surround the lakes. Lake Chilling Tso is smaller in perimeter (8 km) and area (4.5 sq. km) as compared to Lake Ryul Tso (perimeter 11 km, area 6 sq. km). The studied watershed of the area represents moderate stream frequency (2.8), mean annual rainfall, and moderate to lower runoff. Both the CIA (36 to 72) and CNK indicators suggest a range of weak to intermediate weathering. The ICV values (lake Ryul Tso ranging from 0.79 to 2.40, lake Chilling Tso ranging from 0.89 to 1.52) indicate that the sediments are compositionally immature and mature, and were likely deposited in active and cratonic tectonic settings, respectively. The results of hydrodynamic sorting and X-ray diffraction (XRD) analysis revealed that the lake sediments are predominantly quartz-dominated, with a notable presence of feldspar and a limited amount of clay minerals. The analytical values of the sediment samples demonstrate a diverse range of source rocks. The study involves weathering component and compositional variation of the sediments, their relationship with climatic conditions, geomorphic features, basin environment, and catchment lithology.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"62 13","pages":"1421 - 1432"},"PeriodicalIF":0.7,"publicationDate":"2024-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143108485","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":"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}