Petrology最新文献

{"title":"First Evidence of High-Pressure Metamorphism in the Western Flank of the Belomorian Province, Late Paleoproterozoic Lapland–Kola Orogen","authors":"P. Ya. Azimov,&nbsp;A. M. Lezzhov,&nbsp;A. V. Stepanova","doi":"10.1134/S0869591126700074","DOIUrl":"10.1134/S0869591126700074","url":null,"abstract":"<p>An overprinted high-pressure metamorphic mineral assemblage (<i>Opx + Bt + Grt</i>) is found for the first time in an Early Paleoproterozoic gabbronorite dike in the western flank of the Belomorian province. The peak metamorphic conditions (a pressure of 12–15 kbar and temperature of 700–750°C) were estimated using multiequilibrium thermobarometry. This high-pressure metamorphism was related to the Late Paleoproterozoic Lapland–Kola collision.</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"34 4","pages":"382 - 383"},"PeriodicalIF":1.0,"publicationDate":"2026-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148532382","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":"Origin of the Dunite Block of the Monchegorsk Layered Mafic-Ultramafic Complex, Baltic Shield: Evidence from Mineralogical and Geochemical Data","authors":"M. M. Bogina,&nbsp;A. V. Chistyakov,&nbsp;E. V. Sharkov,&nbsp;E. V. Kovalchuk","doi":"10.1134/S0869591126700049","DOIUrl":"10.1134/S0869591126700049","url":null,"abstract":"<div><p>The paper reports the results of detailed mineralogical and geochemical study of the Dunite block in the Paleoproterozoic Monchegorsk complex, Baltic Shield. This block forms an autonomous body at the intersection of the sublatitudinal and sublongitudinal branches of the Moncha pluton. It is composed mainly of adcumulus dunite grading into poikilitic peridotite in the upper part of the section. The central part of the block is occupied by the Sopcheozero chromite deposit. It is shown that the Dunite block is not related to the layered series of the Moncha Pluton by fractionation of a common magma, but was formed through an independent influx of a more primitive high-Mg, Cr-rich (komatiite) magma, which is confirmed by the presence of the highest Mg olivine (<i>Fo</i>₉₃) and higher Cr and Mg spinels compared to the dunites from the ultramafic part of the Layered Series of the Moncha Pluton. These differences are emphasized by the variations of Ni/Cu and Pd/Ir ratios in the bulk rock compositions, as well as by estimated characteristics of the primary melts: 8.44 wt % FeO, 10.26 wt % MgO for the rocks of the Layered Series and 22–25 wt % MgO, 10.5–11.5 wt % FeO for the rocks of the dunite block. The geochemistry and mineralogy of the rocks of the Dunite block reflect fractionation of the primary melt expressed in the upward accumulation of large-ion lithophile elements (LILE) as well as the formation of the olivine–chromite cumulates with the high contents of intercumulus minerals (pyroxenes, more rarely, plagioclase) and an increase of TiO₂ content in spinel in the upper portions of the section. It is suggested that the high-Cr magma emplaced along a channel in the tectonized zone and precipitated chromite with increasing Cr₂O₃ and MgO in the central part of the section. The chemical composition of ore chromite from the Sopcheozero deposit resembles those of the Archean and Paleoproterozoic chromitites, which formed in a magma conduit system and represent a component of ultramafic horizons of the layered complexes (Kemi, Baltic Shield; Uitkomst, South Africa; Sukinda, Indian shield). The similarity of major minerals (olivine and chromite) from dunites to those of peridotites from ophiolite complexes in the diagram (Arai, 1994) is likely explained by the formation of some grains at mantle depths near the crust–mantle boundary, with their subsequent entrapment by forming high-Mg melt, which was parental for the Dunite block. The formation of revealed extremely high-Mg compositions of olivine up to <i>Fo</i>₉₈ with an inverse zoning within chromitites at the absence of typical fractionation trends was related to the subsolidus re-equilibration of olivine with chromite rather than to the crystallization from a melt.</p></div>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"34 3","pages":"237 - 263"},"PeriodicalIF":1.1,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148060976","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":"New Calibration of the Ti4+/Ti3+ Ratio in Silicate Melts: From Simple Slags to Lunar Basalts","authors":"A. A. Borisov","doi":"10.1134/S0869591126700062","DOIUrl":"10.1134/S0869591126700062","url":null,"abstract":"<p>Published experimental data were used in a new calibration of the dependence of the Ti⁴⁺/Ti³⁺ ratio in silicate melts on temperature, oxygen fugacity, and melt composition. The standard error in determining <span>({text{log}}left[ {{{{{X}_{{{text{Ti}}{{{text{O}}}_{{text{2}}}}}}}} mathord{left/ {vphantom {{{{X}_{{{text{Ti}}{{{text{O}}}_{{text{2}}}}}}}} {left( {{{X}_{{{text{Ti}}{{{text{O}}}_{{{text{1}}{text{.5}}}}}}}}} right)}}} right. kern-0em} {left( {{{X}_{{{text{Ti}}{{{text{O}}}_{{{text{1}}{text{.5}}}}}}}}} right)}}} right])</span> by the proposed equation <span>({text{log}}left[ {{{{{X}_{{{text{Ti}}{{{text{O}}}_{{text{2}}}}}}}} mathord{left/ {vphantom {{{{X}_{{{text{Ti}}{{{text{O}}}_{{text{2}}}}}}}} {left( {{{X}_{{{text{Ti}}{{{text{O}}}_{{{text{1}}{text{.5}}}}}}}}} right)}}} right. kern-0em} {left( {{{X}_{{{text{Ti}}{{{text{O}}}_{{{text{1}}{text{.5}}}}}}}}} right)}}} right])</span> = 0.216log <i>f</i>O₂ – 0.280<span>({{X_{{{text{Ti}}{{{text{O}}}_{2}}}}^{2}} mathord{left/ {vphantom {{X_{{{text{Ti}}{{{text{O}}}_{2}}}}^{2}} {X_{{{text{Si}}{{{text{O}}}_{2}}}}^{{}}}}} right. kern-0em} {X_{{{text{Si}}{{{text{O}}}_{2}}}}^{{}}}})</span> – 2.885<span>({{{{X}_{{{text{A}}{{{text{l}}}_{{text{2}}}}{{{text{O}}}_{{text{3}}}}}}}} mathord{left/ {vphantom {{{{X}_{{{text{A}}{{{text{l}}}_{{text{2}}}}{{{text{O}}}_{{text{3}}}}}}}} {{{X}_{{{text{Si}}{{{text{O}}}_{{text{2}}}}}}}}}} right. kern-0em} {{{X}_{{{text{Si}}{{{text{O}}}_{{text{2}}}}}}}}})</span> – 5.727<i>X</i>_MgO/<span>({{X}_{{{text{Si}}{{{text{O}}}_{{text{2}}}}}}})</span> – 5.997<i>X</i>_CaO/<span>({{X}_{{{text{Si}}{{{text{O}}}_{{text{2}}}}}}})</span> – 3.864<span>({{{{X}_{{{text{N}}{{{text{a}}}_{{text{2}}}}{text{O}}}}}} mathord{left/ {vphantom {{{{X}_{{{text{N}}{{{text{a}}}_{{text{2}}}}{text{O}}}}}} {{{X}_{{{text{Si}}{{{text{O}}}_{{text{2}}}}}}}}}} right. kern-0em} {{{X}_{{{text{Si}}{{{text{O}}}_{{text{2}}}}}}}}})</span> + 12 433(<i>X</i>_MgO + <i>X</i>_CaO + <span>({{X}_{{{text{N}}{{{text{a}}}_{{text{2}}}}{text{O}}}}})</span>)/(<span>({{X}_{{{text{Si}}{{{text{O}}}_{{text{2}}}}}}})</span><i>T</i>(K)) + 2.490 (where <i>X</i>_<i>i</i> is the mole fraction of component <i>i</i> in the melt) is 0.065, which is equivalent to an error of 0.24 in determining log <i>f</i>O₂. It has been shown that in melts corresponding to the compositions of lunar glasses (Delano, 1986), the Ti³⁺/Ti_tot ratio at 1300°C and oxygen fugacity at the iron–wüstite (IW) buffer level is only 0.03 on average. Even this small Ti³⁺ content should be mostly oxidized to Ti⁴⁺ during melt cooling/quenching into glass as a result of redox exchange with Fe³⁺.</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"34 3","pages":"349 - 359"},"PeriodicalIF":1.1,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148060812","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-Pressure (7–17 MPa) and High-Temperature (1250–1300°C) Melting of Marly Limestone from a Pyrometamorphic Complex of Mongolia. Formation of Carbonate–Silicate and Carbonate Melts","authors":"V. Yu. Chevychelov,&nbsp;A. R. Kotelnikov,&nbsp;A. A. Viryus,&nbsp;I. S. Peretyazhko,&nbsp;N. I. Suk,&nbsp;A. V. Yosimovska,&nbsp;E. A. Savina","doi":"10.1134/S0869591126700037","DOIUrl":"10.1134/S0869591126700037","url":null,"abstract":"<p>Melting of marly limestone from the Khamaryn-Khural-Khiid pyrometamorphic complex in East Mongolia was experimentally studied. The mineral and phase composition of the partly melted marly limestone sample used in the experiments was as follows: calcite (~59 wt %), silicate glasses of various compositions, melilite (gehlenite–akermanite), Al-clinopyroxene, Na–Ca nepheline (davidsmithite), celsian, magnetite, relict grains of sedimentary rock (quartz, albite–anorthoclase, plagioclase, and zircon), and other rarer minerals. Extremely calcium-rich phases were found in the solid experimental products: larnite, a gehlenite-like mineral, calcite, and transformation products of carbonate and carbonate–silicate melts. Carbon content was determined in the carbonate–aluminosilicate glass using electron probe microanalysis (EPMA), and the presence of the <span>({text{CO}}_{3}^{{2 - }})</span> complex was confirmed by Raman spectroscopy. It was established that calcite remains stable in the marly limestone in the temperature range 1250–1300°C and at a CO₂ partial pressure of approximately 7–17 MPa. However, the phase state of CaCO₃ (molten or crystalline) at the high-temperature stage of the experiments could not be reliably determined from the habit and composition of calcite grains in the experimental products. The physicochemical conditions of synthesis, stability, and liquid immiscibility of carbonate and carbonate–silicate melts obtained in the experiments may be used to evaluate the possibility of their formation during melting of carbonate–silicate sedimentary rocks not only in pyrometamorphic complexes, but also under low-pressure high-temperature crustal conditions.</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"34 3","pages":"304 - 324"},"PeriodicalIF":1.1,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148061035","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":"Metamorphism of the Chupa Gneisses and Gabbroids in the Belomorian Mobile Belt, Fennoscandian Shield, Northwestern Russia: A Comparative Study of the P–T Partial Melting Parameters and Isotopic Age of the Migmatized Rocks","authors":"A. V. Yurchenko,&nbsp;Sh. K. Baltybaev,&nbsp;O. L. Galankina,&nbsp;N. G. Rizvanova,&nbsp;A. M. Nikolaeva,&nbsp;T. A. Myskova","doi":"10.1134/S0869591126700025","DOIUrl":"10.1134/S0869591126700025","url":null,"abstract":"<p>The rocks of the Chupa paragneiss formation are intruded by bodies of gabbroids (gabbro-norites and gabbro-anorthosites), and all of the rocks are metamorphosed. The estimated <i>P–T</i> metamorphic parameters are <i>T</i> = 650–750°C and higher and <i>P</i> = 8–11 kbar. The U–Pb monazite and titanite dates indicate that the early Proterozoic metamorphism and migmatization of the Chupa aluminous gneisses and gabbro-anorthosites occurred 1845 ± 4 Ma (titanite age) and 1855 ± 4 Ma (monazite age). Despite the 10-Ma age difference obtained from the two minerals, they could form during a single event that affected the gabbroids and their host gneisses, and the age difference between the titanite and monazite is a consequence of the lower closure temperature of the U–Pb system of titanite compared to that of monazite. The <i>P–T</i> parameters of metamorphism and migmatization, corresponding to the conditions of the high-temperature amphibolite and low-temperature high-pressure granulite facies, likely pertain to the formation of the Belomorian complex as a foreland structure in the Paleoproterozoic.</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"34 3","pages":"264 - 280"},"PeriodicalIF":1.1,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148061033","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":"Graphite Flakes from the Luk Ulo Complex, Central Java, Indonesia: A Geothermobarometer Modelling and Host Rock Characteristics","authors":"Isyqi,&nbsp;Nugroho Imam Setiawan,&nbsp;Ferian Anggara,&nbsp;Mohammad Al’Afif","doi":"10.1134/S0869591125600351","DOIUrl":"10.1134/S0869591125600351","url":null,"abstract":"<p>The graphite identified in the metapelites of the Luk Ulo Complex, Central Java, occurs as flakes spanning a broad size range, from fine particles of about 10 µm to large crystals approaching 4500 µm. The flakes coexist with quartz, chlorite, and white mica/phengite, forming well-developed schistosity in the graphite-phyllite rocks. These conditions represent that the graphite flakes are formed under metamorphic conditions. The metamorphic conditions of the graphite-bearing metapelites were evaluated using three analytical techniques: mineral-chemistry thermobarometry involving chlorite and phengite, pseudosection modelling, and Raman spectroscopic determination of CM temperatures. The results indicate that the metamorphic conditions of the graphite-bearing rocks from the Luk Ulo Complex range between 4 to 6 kbar in pressure and from 340 to 380°C in temperature that fall within the Greenschist facies. The geochemical analysis reveals the dominance of SiO₂, Al₂O₃, and Fe₂O₃, with a rare earth element pattern suggesting a carbon-rich shale or greywacke protolith derived from a Continental Island Arc and Oceanic Island Arc setting. The regional metamorphic event responsible for the formation of graphite flakes is considered to have resulted from a subduction and collision event between Sundaland and various continental fragments derived from Gondwana in central Indonesia during the Cretaceous period. Other regions with similar geological settings in the Cretaceous accretionary-collision complexes in central Indonesia may be potential sources for similar graphite flakes and associated host rocks.</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"34 3","pages":"360 - 380"},"PeriodicalIF":1.1,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148061037","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":"Mineralogical Indicators of the Formation Conditions of Gabbro and Associated Copper Sulfide and Precious Metal Mineralization of the Volkovskiy Massif, Ural Platinum Belt","authors":"E. V. Anikina,&nbsp;I. A. Rusin","doi":"10.1134/S0869591125600302","DOIUrl":"10.1134/S0869591125600302","url":null,"abstract":"<p>The paper presents data on the composition of olivine gabbro from the Volkovskiy and Kumbinskiy massifs and the composition of the rock-forming and ore minerals. Both massifs are located near the eastern contact of the Ural Platinum Belt with the Silurian−Devonian volcanic complexes of the Tagil megazone and both host copper sulfide mineralization with platinum-group metals and gold, which are associated with amphibole-bearing rock types. The earlier amphibole in olivine gabbros of both massifs is magnesiohastingsite (<i>X</i>_Mg = 0.68–0.75; 2–2.5 wt % TiO₂; F/Cl = 2–6), which crystallized at <i>T</i> ≈ 850°C, <i>P</i> ≈ 2–3 kbar under oxidizing conditions (∆NNO &gt; 1), simultaneously with titanomagnetite (3–8 wt % TiO₂), bornite, and chalcopyrite. As the temperature decreased (<i>T</i> ≈ 750°C; ∆NNO &gt; 1), the clinopyroxene and earlier magnesiohastingsite were replaced by magnesiohornblendite (1.32 wt % TiO₂; F/Cl = 5). Later amphibole (magnesiohastingsite, pargasite, hastingsite, ferropargasite, magnesiohornblendite, and edenite) in the ore-bearing gabbro of the Volkovskiy massif has a variable composition and differs from the earlier amphibole in having a low Mg# (<i>X</i>_Mg = 0.71–0.29) and a low TiO₂ content (0.10–0.96 wt %) and in being enriched in halogens, primarily Cl (F/Cl = 0.4–0.6). The later amphibole is found in a low-temperature (&lt;600°C) mineral association with magnetite (&lt;2 wt % TiO₂), ilmenite (&lt;0.1 wt % MgO; &gt;3 wt % MnO), bornite (±chalcocite or digenite), and minerals of precious metals (Pd−Te and Au−Ag). The enrichment of the later amphibole in Cl (F/Cl = 0.4–0.6), in contrast to the earlier magnesiohastingsite (F/Cl = 2–6), suggests the influx of fluid from an external source. Our data indicate that postmagmatic processes have played a significant role in forming the copper sulfide and precious-metal mineralization in the Volkovskiy massif and, likely, also in other massifs of the Ural Platinum Belt.</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"34 3","pages":"281 - 303"},"PeriodicalIF":1.1,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148061034","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":"Geothermobarometry of Pyroxenes from Ultramafic Rocks of the Monchegorsk Intrusive Complex: 1. Traditional Approach","authors":"D. D. Eremin,&nbsp;A. A. Ariskin,&nbsp;S. N. Sobolev,&nbsp;I. V. Pshenitsyn,&nbsp;V. F. Smolkin,&nbsp;V. O. Yapaskurt,&nbsp;N. N. Korotaeva,&nbsp;G. S. Nikolaev","doi":"10.1134/S0869591126700050","DOIUrl":"10.1134/S0869591126700050","url":null,"abstract":"<p>This paper reports testing of seven geobarometers (pyroxene and polymineralic) from five studies (Nimis, 1995; Putirka, 2008; Fumagalli et al., 2017; Ziberna et al., 2017; Wang et al., 2021) on a test set of experimental data (TSED), including results from 64 subliquidus and 31 subsolidus experiments in high-Mg systems (Mg# &gt; 0.63, olivine <i>Fo</i> &gt; 85%) at pressures no higher than 10 kbar. The most consistent pressure estimates were obtained using the temperature-independent <i>Cpx</i>-only geobarometer of Nimis (1995). The use of temperature-dependent geobarometers yielded highly scattered pressure values, even at given experimental temperatures. The same seven geobarometric models were applied to estimate the crystallization conditions of 18 samples of mafic–ultramafic rocks from the Monchegorsk Intrusive Complex in Murmansk region (Russia). The compositions of minerals from plagioclase harzburgite, orthopyroxenite, and melanorite from three locations were used for these calculations: (1) a deep ultramafic body from borehole M-1 cutting the middle and lower zones of the Monchetundra intrusion near its contact with the Monchegorsk pluton; (2) drill cores from borehole M-20 within the Dunite block of the Monchegorsk pluton; and (3) dump piles of Mine No. 5 on Mt. Travyanaya. The barometric calculations gave a wide pressure range from ~1 to 5–6 kbar. The models by Nimis (1995) and Wang et al. (2021) yielded the most consistent values: 1.2 ± 0.5 and 0.6 ± 1.4 kbar for borehole M-1, 1.0 ± 0.4 and 0.8 ± 0.6 kbar for borehole M-20, and 2.3–2.4 kbar for the Mt. Travyanaya peridotites. Additional verification was carried out using a semiempirical <i>Cpx</i>-only geobarometer calibrated by us using the TSED. This geobarometer showed the following values for the same array of natural pyroxene compositions: 0.6 ± 0.6 kbar for borehole M-1, 0.8 ± 0.5 kbar for borehole M-20, and 3.2 ± 1.5 kbar for the Mt. Travyanaya peridotites. Thus, the rocks of the latter location bear evidence for the deepest origin among all rocks of the Monchegorsk pluton, which should be considered during reconstructions of the original position and generalized stratigraphic section of this intrusion.</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"34 3","pages":"325 - 348"},"PeriodicalIF":1.1,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148061036","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":"Zircon Geochemical Constraints on the Evolution of Pan-African Post-Collisional Granitoids in Katchuan and Boje, Southeastern Nigeria Basement Complex","authors":"Chinedu Uduma Ibe,&nbsp;Ekeleme Ifeoma Aquila,&nbsp;Aghaebita Ifeoma Chinwendu","doi":"10.1134/S0869591125700419","DOIUrl":"10.1134/S0869591125700419","url":null,"abstract":"<p>We present the first LA-ICP-MS trace element data for zircons from two Pan-African post-collisional granitoids of the southeastern Nigerian Basement Complex: the Katchuan granodiorite and the Boje biotite granite. Whole-rock geochemistry classifies both suites as peraluminous, calc-alkaline S-type granitoids derived from melting of continental or reworked arc crust. Zircons from Boje are enriched in ΣREE, Th, U, and Pb relative to Katchuan, reflecting crystallization from a more evolved melt. Both populations exhibit HREE enrichment with positive Ce and negative Eu anomalies, but many grains show atypically high LREE contents. Most zircons record Th/U ≥ 0.5, supporting an igneous origin. Discrimination plots (La_N–Pr_N, (Sm/La)_N–La, Ce/Ce*–(Sm/La)_N) indicate dominantly magmatic signatures for Katchuan zircons, whereas Boje zircons occupy fluid-influenced domains. Elevated Ca, correlating with P, suggests local interference from apatite inclusions. Ti-in-zircon thermometry yields mean crystallization temperatures of ~670 and ~750°C for Boje and Katchuan granites respectively, while zircon saturation temperatures exceed these by 100–140°C. Overall, zircon chemistry reveals magmatic growth with hydrothermal overprinting at Boje, processes that likely promoted rare-metal mobility (Be, Nb, Ta).</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"34 2","pages":"212 - 236"},"PeriodicalIF":1.1,"publicationDate":"2026-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147631736","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":"Synchronism of Rift and Platform Magmatism in Eastern Siberia at the Permian–Triassic Boundary","authors":"N. A. Krivolutskaya,&nbsp;I. T. Rass,&nbsp;A. A. Konyshev,&nbsp;B. V. Belyatsky,&nbsp;B. I. Gongalsky,&nbsp;N. M. Svirskaya","doi":"10.1134/S0869591125700377","DOIUrl":"10.1134/S0869591125700377","url":null,"abstract":"<p>The Siberian igneous province is made up of two types of volcanic rocks that formed under different geodynamic conditions: platform and rift ones, which were previously thought to have formed sequentially. The paper presents the first data indicating that rift and platform magmatism occurred simultaneously in this LIP, as follows from the presence of contrastingly different rocks in the same geological sections, including basalts, picrites, and tuffs. The most interesting rocks are picrite basalts and picrites, which provide evidence for the successive intrusion of mantle magmas from west to east along the southern boundary of the Yenisei–Khatanga trough. This indicates that a large paleorift developed in this direction. Variations in the contents and ratios of trace elements in the mantle rocks demonstrate their formation at greater depths during the evolution of magmatism. None of the current genetic models of the province takes into account these structural features, which call for further adequate explanations.</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"34 2","pages":"110 - 135"},"PeriodicalIF":1.1,"publicationDate":"2026-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147631735","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}