Petrology最新文献

{"title":"Archean Block in the Core of the Paleoproterozoic Lapland-Kola Orogen: New Data on the Composition and Age of Rocks from the Poriya Guba Islands","authors":"A. V. Samsonov,&nbsp;K. G. Erofeeva,&nbsp;O. A. Maksimov,&nbsp;A. V. Stepanova,&nbsp;Yu. O. Larionova","doi":"10.1134/S0869591125700043","DOIUrl":"10.1134/S0869591125700043","url":null,"abstract":"<div><p>Petrological and geochronological (zircon, U-Th-Pb (LA-ICP-MS)) studies of rocks from the Poriya Guba tectonic mélange exposed on the Ozerchanka and Palenyi islands were carried out to decipher the composition and tectonic history of the Paleoproterozoic Lapland-Kola orogen (LKO). Tonalite–trondhjemite–granodiorite (TTG) (<i>Grt</i>)–<i>Cpx</i>–<i>Opx</i> gneisses dominate on Ozerchanka Island. They contain numerous bodies of mafic granulites and are intruded by syn- and post-tectonic granitoids. The TTG gneisses are Archean in age (&gt;2.6 Ga, Т_Nd(DM) = 2.9–3.0 Ga). The HREE depletion in the gneisses indicates that the parental melts of their igneous protoliths were formed in equilibrium with a garnet-bearing residue. Mafic granulite bodies vary widely in geochemistry and likely represent fragments of several Paleoproterozoic mafic intrusions and dikes. Mineral assemblages in the gneisses recorded the early granulite-facies (<i>Т</i> = 780–820°С and <i>Р</i> = 8.6–9.4 kbar) and later amphibolite-facies (<i>Т</i> = 640–650°С and <i>Р</i> = 6.7–7.3 kbar) metamorphic events that occurred at 1.9 Ga according to zircon ages. On Palenyi Island, the banded <i>Grt</i>–<i>Cpx</i>–<i>Opx</i> gneisses are predominant and vary in composition from basaltic andesites to rhyolites. The volcanic protoliths of these rocks have island-arc geochemical signatures, a Paleoproterozoic age of 1958 ± 6 Ma, and juvenile origin (ε_Nd(1960) = +1.7 ÷ +3.1; Т_Nd(DM) = 2.2–2.3 Ga). These rocks were metamorphosed under the granulite-facies conditions at about 1.9 Ga. Two models can explain the presence of the Archean block in the Poriya Guba tectonic mélange, which is composed of the Paleoproterozoic juvenile island-arc complexes in the core of the LKO. First, this Archean block could represent a single fragment of Archean lithosphere that was separated during Paleoproterozoic continental rifting and opening of the Lapland–Kola ocean and then was tectonically juxtaposed with Paleoproterozoic subduction complexes during the Lapland-Kola collisional orogeny. Second, the Archean block may represent the margin of an adjacent Archean continent exposed in an erosional window within the Paleoproterozoic Poriya Guba tectonic nappe.</p></div>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"33 3","pages":"163 - 179"},"PeriodicalIF":1.1,"publicationDate":"2025-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145171513","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":"Archean Pon’goma-Navolok Granulite–Charnockite–Enderbite Complex, Northern Karelia: Geological Structure, Composition, and Parameters of Formation","authors":"V. M. Kozlovskii,&nbsp;E. B. Kurdyukov,&nbsp;M. V. Strel’nikov,&nbsp;V. V. Travin,&nbsp;T. F. Zinger,&nbsp;M. A. Golunova,&nbsp;I. S. Volkov,&nbsp;S. A. Ushakova,&nbsp;V. I. Taskaev,&nbsp;A. I. Yakushev","doi":"10.1134/S0869591125700018","DOIUrl":"10.1134/S0869591125700018","url":null,"abstract":"<p>The paper presents original detailed data obtained by the authors on the Archean Pon’goma-Navolok granulite and charnockite massif in northern Karelia: a geological map of the massif and its surroundings, data on the petrography of the magmatic and metamorphic rocks, and the <i>P</i>–<i>T</i> parameters evaluated for major rock types by the techniques of multimineral thermomabometry and pseudosections. The Pon’goma-Navolok massif is determined to have formed as two intrusive phases at different crustal levels. The first intrusive phase corresponds to the massif of clinopyroxene–orthopyroxene charno-enderbites that crystallized at 8–11.2 kbar and 730–740°C. The second phase comprises dikes of orthopyroxene–biotite charnockites, which formed at 5.6–6.8 kbar and 830–850°C, and biotite granites, which crystallized at 6.8–7.0 kbar and 730–740°C. The dikes most likely correspond to different temperature and water-activity facies. The charnockites and granites were formed by processes of charnockitization and granitization of the charno-enderbites under the effect of saline aqueous solutions. The granulite-facies metamorphism of the metabasite blocks hosted in the charno-enderbite intrusion was of contact nature and was induced by the thermal effect of the charno-enderbites on the roof and wall rocks of the magma chamber. The high metamorphic temperatures of the metabasites (&gt;900°C) and the absence of migmatization aureoles are explained by low water contents in the enderbites.</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"33 3","pages":"205 - 240"},"PeriodicalIF":1.1,"publicationDate":"2025-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145171854","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":"On the Connection between Sulfide Inclusions in Olivine from Tolbachik Volcano and Fluids from Mafic Cumulates beneath the Klyuchevskoy Group Volcanoes","authors":"A. G. Simakin","doi":"10.1134/S086959112570002X","DOIUrl":"10.1134/S086959112570002X","url":null,"abstract":"<p>The high activity of the Klyuchevskoy group volcanoes in the Holocene suggests that considerable volumes of partly solidified magma (cumulates) and mafic–ultramafic intrusions have accumulated in the crust. Together with extensive fluid flow typical the zones of rapid subduction of an old oceanic plate, this provides conditions for the formation of a fluid–magma ore-forming system. Olivine with sulfide inclusions was found in the eruption products of Tolbachik Volcano. Its investigation may provide insight into the composition of crustal fluid of such ore-magmatic systems. The interaction of reduced water-poor fluid with oxidized basaltic melt (NNO + 1.5) containing 2000–3000 ppm sulfur was theoretically modeled. It was shown that at a local fluid content higher than ~1–2 wt %, sulfur in the melt is reduced and sulfide droplets are formed. Sulfur reduction in the melt can also be caused by the dissolution of SO₂, which is the main sulfur species in fluid at log <i>f</i>O₂ ≥ NNO + 1.5. This effect is related to the higher degree of sulfur oxidation (S⁺⁶) in melt, where <span>({text{SO}}_{4}^{{2 - }})</span> is the only oxidized sulfur species, compared with SO₂ (S⁺⁴) in fluid. According to calculations, sulfide formation begins after dissolution of approximately 2000–3000 ppm sulfur in the SO₂ form in melt at log <i>f</i>O₂ ≥ NNO + 1. Interaction with fluid with small contents of precious metals (PM) produces sulfide melt droplets with PM contents corresponding to the background values in the melt. According to experimental evidence, Pt and Pd are highly soluble in reduced water-poor fluids in the form of carbonyls, whereas Au is low soluble; in contrast, Au solubility is very high in oxidized fluids (NNO + 1 to NNO + 1.5). Reaction with mineralized fluid containing up to tens of ppm PM produces sulfide melt enriched in Au (oxidized fluid) or Pt (reduced fluid). Interaction of melt with water-poor fluid causes local dehydration and an increase in liquidus temperature, which results in rapid olivine crystallization at high overcooling. The localization of phase transitions at the boundary of fluid bubbles facilitates the entrapment of sulfide droplets by olivine. The rare occurrence of sulfide inclusions in olivine from Tolbachik Volcano can be related to the rapid dissipation of the local effect of magma interaction with small amounts of fluid and dissolution of the precipitated sulfide phase in the melt.</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"33 3","pages":"253 - 268"},"PeriodicalIF":1.1,"publicationDate":"2025-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145171855","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 Evolution of Sulfide Melts as a Key Factor in the Distribution and Concentration of Platinum-Group Elements in Norilsk Ores","authors":"V. D. Brovchenko","doi":"10.1134/S0869591124700322","DOIUrl":"10.1134/S0869591124700322","url":null,"abstract":"<p>The Norilsk–Talnakh magmatic sulfide Cu–Ni–PGE (platinum-group elements) deposits were formed by the accumulation of metals in immiscible sulfide melt comagmatic with the parental mafic–ultramafic magma. In this study, the main types of magmatic sulfide ores of the Norilsk–Talnakh deposits are considered as manifestations of different stages in the evolution of the initial sulfide melts. In the context of the overall evolution of Norilsk sulfide melts, the earliest ores are Cu-poor pyrrhotite ores with high concentrations of Rh and IPGE (Os, Ir, and Ru), which were discovered at the Talnakh deposit. The second stage of sulfide melt evolution was marked by the formation of most disseminated ores and Cu- and PGE-poor massive pyrrhotite ores. The massive and disseminated ores were formed independently from each other, but generally correspond to the melts with identical compositions. The only exception is low-sulfur PGE-rich ores from the Upper Gabbroid rocks of the differentiated intrusions, which were affected by wall rock assimilation and early magmatic degassing. It has been shown that the concentrations of ore components in the disseminated sulfides, which are examples of in-situ crystallized droplets of immiscible sulfide melt, vary depending on the composition and degree of fractionation of the parental silicate magma. During the final stage, the crystallization of the residual sulfide melts led to the formation of Cu-rich ores with high Pt and Pd contents. The compositions of these main ore types are compared with the compositions (including trace elements) of their base metal sulfides (BMS). All element dependencies in the massive ores follow the fractional crystallization trend of the sulfide melt. PGE in Norilsk ores are concentrated in distinct platinum-group minerals (PGM) and occur as trace elements in BMS. Rhodium and IPGE are concentrated in pyrrhotite, pentlandite, and pyrite; Pt is occasionally found in pyrite; whereas Pd is found predominantly in pentlandite. The concentration of Pd in pentlandite increases from the Cu-poor to Cu-rich ores. Based on a detailed analysis with the application of several methods, the Pd-rich pentlandite (containing 4.84 wt % Pd) from massive primary magmatic Cu-rich <i>MSS–ISS</i> ores is thought to have been formed by a high-temperature mechanism involving a reaction with sulfide melt. Using <i>X</i>-ray absorption spectroscopy (XAS), the oxidation state of Pd in pentlandite (2⁺) and its occurrence in the form of a solid solution, in which Pd apparently replaces Ni in the pentlandite structure, were identified for the first time.</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"33 1 supplement","pages":"S1 - S75"},"PeriodicalIF":1.0,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143865569","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":"Minerals of the Тochilinite–Ferrotochilinite Series from Rocks of the Urals and Trans-Urals: Мineral Аssociations, Сhemical Сomposition, and Genesis","authors":"S. V. Pribavkin,&nbsp;E. V. Pushkarev,&nbsp;I. S. Chashchukhin,&nbsp;Yu. V. Erokhin,&nbsp;A. V. Korovko","doi":"10.1134/S0869591124700358","DOIUrl":"10.1134/S0869591124700358","url":null,"abstract":"<div><p>The paper presents the results of studying the scarce iron–magnesium sulfide–hydroxides of the tochilinite–ferrotochilinite series with the ideal formula 6FeS·5Mg(OH)₂. These minerals are formed during serpentinization of ultrabasites of different nature and were described in peridotites of the Kempirsai, Khabarny, Kytlym and Uktus massifs in the Urals and the Verkhne-Iusskaya area of the Shaim petroleum region of Western Siberia. The aim of this work is to examine the poorly studied chemical composition of tochilinite, to determine its mineral associations and conditions of formation. The minerals were analyzed by optical and electron scanning microscopy, Raman and IR spectroscopy. Based on the magnesium number (<i>Х</i>_Mg), the minerals could be divided into tochilinite and ferrotochilinite. High-Mg minerals (<i>Х</i>_Mg = 0.73–0.79) are found in the Uktus massif and in the Verkhne-Iusskaya area, and low-Mg varieties (<i>Х</i>_Mg = 0.15–0.38) occur in the Khabarny and Kytlym massifs. The presence of mixed-layer phases represented by the alternation of nano-scale layers of tochilinite or ferrotochilinite with serpentine is assumed. The chromium-bearing varieties of tochilinite are noted. Mechanisms and chemical reactions leading to the formation of tochilinites during the low-temperature transformation of peridotite in the presence of water are discussed. In most cases, this is the interaction of metamorphic water with magmatic sulfides during the serpentinization of peridotite, or the influence of sedimentary or another waters containing dissolved sulfur on them. It is concluded that tochilinite served as a sulfur absorbent during early reticulate serpentinization of ultramafic rocks. Tochilinite could be used as a promising geothermometer for low-temperature ultramafic mineral assemblages.</p></div>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"33 2","pages":"112 - 129"},"PeriodicalIF":1.0,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143856529","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":"Evidence for Partial Melting in Mantle Xenoliths of Spinel Lherzolites of Zhokhov Island, De Long Archipelago, Eastern Arctic","authors":"S. A. Silantyev,&nbsp;D. D. Badyukov,&nbsp;A. G. Akhmetshin,&nbsp;E. A. Krasnova","doi":"10.1134/S086959112470036X","DOIUrl":"10.1134/S086959112470036X","url":null,"abstract":"<div><p>Zhokhov Island belongs to the De Long Archipelago located in the Eastern sector of the Russian continental shelf within the Arctic Basin. The island is a young volcanic center and is composed of lava flows of alkaline olivine-porphyry basalts and subordinate limburgites. The study was aimed at identifying the possible regional and geodynamic factors influencing the specifics of the partial melting and mineral transformations in mantle xenoliths of Zhokhov Island. Five xenoliths selected from alkali basalt samples on Zhokhov Island were studied using a scanning electron microscope. The data obtained allowed us to conclude that the formation of high-sodium glasses in the mantle xenoliths of Zhokhov Island is associated with the interaction between spinel lherzolites and parental melts of host olivine basalts. At the same time, high-potassium glasses inside mantle xenoliths were formed in situ during the melting of a primary potassium-bearing phase, likely phlogopite. The formation of two distinct compositionally contrasting recrystallization zones in contact between the mantle xenoliths and the host basalt is caused by the evolution of host alkaline silicate melt from sodic to potassic composition. Signs of activation of young intraplate magmatism that brought up the fragments of metasomatized shallow mantle to the surface are established over a large area of the Arctic Basin within the HALIP large igneous province.</p></div>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"33 2","pages":"81 - 93"},"PeriodicalIF":1.0,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143856530","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental Study of Chemical Counterdiffusion of Major Components (SiO2, Al2O3, Na2O, CaO, MgO, and FeO) and ({text{CO}}_{3}^{{2 - }}) Anion during Interaction of Basalt and Kimberlite Melts under Upper Mantle P–T Conditions","authors":"E. S. Persikov,&nbsp;P. G. Bukhtiyarov,&nbsp;A. G. Sokol,&nbsp;A. N. Nekrasov,&nbsp;D. M. Sultanov","doi":"10.1134/S0869591124700346","DOIUrl":"10.1134/S0869591124700346","url":null,"abstract":"<p>This paper reports new experimental results on the chemical counterdiffusion of major components (SiO₂, Al₂O₃, Na₂O, CaO, MgO, and FeO) and the <span>({text{CO}}_{3}^{{2 - }})</span> anion during interaction of basalt and kimberlite melts under upper-mantle pressure. The method of diffusion couples was employed on a BARS split-sphere apparatus at 5.5 GPa and 1850°C. It was shown that the rates of chemical counterdiffusion of all major melt species (SiO₂, Al₂O₃, Na₂O, CaO, MgO, and FeO) and the <span>({text{CO}}_{3}^{{2 - }})</span> anion are almost identical during interaction of model basalt and carbonate-bearing kimberlite melts and approximately an order of magnitude higher than the diffusion rates of these components during melt interaction under moderate pressures (100 MPa). The equal diffusion rates of CaO and <span>({text{CO}}_{3}^{{2 - }})</span> indicate that molecular CaCO₃ diffusion from the kimberlitic to basaltic melt (model and natural) occurs also at the high pressure. The diffusion patterns are dramatically different during interaction of natural magnesian basalt and model kimberlite, which was observed for the interaction of these melts at moderate pressure. In addition to the molecular diffusion of CaCO₃ into the magnesian basalt, the diffusion rates of other melt species increase significantly. All diffusing components show weak exponential dependence on concentrations approaching <i>D</i>_<i>i</i> = const, similar to that observed during interaction of such melts at moderate pressures.</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"33 2","pages":"130 - 138"},"PeriodicalIF":1.0,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143856531","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":"Melts of Ocean Island Basalts (OIB) and Their Sources: Evidence from Melt Inclusions and Quenched Glasses of Rocks","authors":"V. B. Naumov,&nbsp;A. V. Girnis,&nbsp;V. A. Dorofeeva","doi":"10.1134/S0869591124700334","DOIUrl":"10.1134/S0869591124700334","url":null,"abstract":"<p>In this paper, we examine the compositions of basaltic melts from ocean islands using our regularly updated database of analyses of melt inclusions in minerals and glasses of igneous rocks. Mean concentrations of major, trace, and volatile components in melts were calculated for the global dataset (22 550 analyses from 33 island systems) and for the most extensively studied complexes (Iceland, Hawaii, Canaries, Galapagos, and Reunion). It was found that the mean contents of most elements fall between the mean compositions of magmas from mid-ocean ridges (most depleted) and intraplate continental complexes (most enriched). Variations of element ratios in particular complexes were considered in detail, and it was found that they can be described by mixing magmas from a depleted source and variably enriched materials. The abundances of trace elements in the supposed mantle sources were estimated. The depleted source is most clearly manifested in Iceland and is almost identical to the depleted mantle the melting of which produces mid-ocean ridge basalts.</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"33 2","pages":"94 - 111"},"PeriodicalIF":1.0,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143856528","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":"Geochemical Characterization, Tectonic Setting, and Metamorphic History of Metabasites from Jandaq Metamorphic Complex, Iran","authors":"Arefeh Heidarianmanesh,&nbsp;Seyed Mohsen Tabatabaei Manesh,&nbsp;Nargess Shirdashtzadeh,&nbsp;Farid Chemale Junior,&nbsp;O. V. Parfenova","doi":"10.1134/S0869591124700371","DOIUrl":"10.1134/S0869591124700371","url":null,"abstract":"<p>Metabasites within the Jandaq Metamorphic Complex (JMC), Iran, offer valuable insights into the region’s magmatic and metamorphic history. Whole-rock geochemical data (major, trace, and rare earth elements) coupled with Sm-Nd isotopes were used to decipher the protolith origin and tectonic setting of formation of these metabasites. Our results demonstrate a predominantly ortho-amphibolitic nature for the JMC metabasites, with igneous protoliths ranging from basalt to andesite based on geochemical discrimination diagrams (Zr versus MgO and Sm/Nd). They exhibit geochemical affinities closer to enriched mid-oceanic ridge basalts (E-MORB) rather than normal MORB, implying a nascent oceanic basin within an intracontinental extensional setting. Trace element signatures (LILE enrichment, HFSE depletion) suggest a metasomatized subcontinental lithospheric mantle (SCLM) or a metasomatized lithospheric mantle beneath the oceanic crust as the parental magma source. Sm-Nd isotopic data suggest a potential plume source for the protoliths. These rocks were metamorphosed further by at least three metamorphic events: M1 (regional metamorphism, Barrovian-type; 616–687°C, 8–11 kbar), M2 (a brittle deformation event), and a later retrograde metamorphism (M3). These findings provide a comprehensive understanding of the geochemical characteristics, tectonic setting, and metamorphic evolution of JMC metabasites, shedding light on the geological history of the Jandaq region as a Paleo-Tethyan remnant.</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"33 2","pages":"139 - 161"},"PeriodicalIF":1.0,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143856581","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":"Petrogenesis and Sources for Rocks of the Rare-Metal Alkaline Burpalа Intrusion (Northern Baikal Region)","authors":"A. G. Doroshkevich,&nbsp;V. M. Savatenkov,&nbsp;A. V. Malyutina,&nbsp;I. A. Izbrodin,&nbsp;I. R. Prokopiev,&nbsp;A. E. Starikova,&nbsp;T. A. Radomskaya","doi":"10.1134/S0869591124700280","DOIUrl":"10.1134/S0869591124700280","url":null,"abstract":"<div><p>The paper reports the results of petrologic and geochemical study of the Burpala alkaline intrusion composed of quartz syenites, alkaline and nepheline syenites, including ore-bearing varieties, which is a part of the Late Paleozoic North Baikal Alkaline Province. Chemically, the studied rocks belong to foid monzosyenites, foid syenites and syenites, ranging from agpaitic to miascitic varieties. Close Sr-Nd isotopic characteristics and geochemical patterns confirm the syngenetic nature of magmas that produced nepheline, alkaline, and quartz syenites. A negative Eu anomaly in the REE patterns and sufficiently low Mg# of rocks testify in favor of a prolonged fractional crystallization of rocks from an alkaline-basic melt. Sr-Nd-Pb isotopic and geochemical characteristics of rocks of the Burpala intrusion reflect the predominance of metasomatized lithospheric mantle in their source. The formation of the rocks of the intrusion, according to the trace element and isotopic data, was complicated by the upper crustal assimilation, which likely determined the genetic relationship between nepheline and quartz syenites within the intrusion.</p></div>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"33 1","pages":"40 - 61"},"PeriodicalIF":1.0,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143769906","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}