Petrology最新文献

{"title":"Tectonites of the Yenisei Shear Zone (Yenisei Ridge): Evidence and Thermomechanical Numerical Model of Generation of Tectonic Overpressure","authors":"O. P. Polyansky,&nbsp;I. I. Likhanov,&nbsp;A. V. Babichev,&nbsp;P. S. Kozlov,&nbsp;S. V. Zinoviev,&nbsp;V. G. Sverdlova","doi":"10.1134/S0869591124010077","DOIUrl":"10.1134/S0869591124010077","url":null,"abstract":"<div><p>Based on the proposed numerical model of the stress-strain state of polymineral rocks, which describes the formation of blastomylonites in the Yenisei Regional Shear Zone (YRSZ) in the Yenisei Ridge, the possibility of local tectonic overpressure exceeding the lithostatic pressure in rocks subjected to shear deformations is shown. For tectonites of the southern (Angara–Kan block) and northern (Isakovka terrane and Garevka complex) segments of the YRSZ, estimates of the maximum overpressure were obtained from 2–3 to 4–5 kbar, which range from 25 to 50% of the lithostatic pressure. It is shown that the excess pressures can be preserved in a local volume on a geological time scale sufficient for their fixation in metamorphic minerals. Model values of overlithostatic pressure in the garnet–amphibole tectonites and geobarometric estimates of peak values during stress metamorphism allow us to offer new evidence for pressure inhomogeneity in natural mineral associations. Using the results of numerical modeling for the evolution of metabasite blastomylonites, it was established that the overpressure at the stage of syn-deformation metamorphism in the shear zone is possible at temperatures up to 600–650°C and not reaching 800°C; the presence of fluid or partial melt prevents the occurrence of overpressure. Magnitudes of excess pressure caused by shear stresses depend on the mineral composition and structure of the rock.</p></div>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"32 1","pages":"16 - 40"},"PeriodicalIF":1.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140803096","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":"Paleoproterozoic Dacite Dikes of the Vorontsovka Terrane, Volga–Don Orogen: Geochemistry, Age, and Petrogenesis","authors":"K. A. Savko,&nbsp;A. V. Samsonov,&nbsp;E. Kh. Korish,&nbsp;N. S. Bazikov,&nbsp;A. N. Larionov","doi":"10.1134/S0869591124020073","DOIUrl":"10.1134/S0869591124020073","url":null,"abstract":"<p>Metamorphosed dacitic porphyry dikes were first found in the western part of the Vorontsovka terrane, which is located in the Paleoproterozoic Volga–Don orogen at the margin of Archean Sarmatia and Volga–Ural cratons. The magmatic protolith age for the metadacites is ca. 2.07 Ga. These are ferrous, metaluminous calc-alkali I-type granitoids. The sodium specialization of the rocks and their low concentrations of Mg, Cr, Ni, and incompatible elements, with significant REE fractionation, the absence of Eu* anomalies, high Sr/Y ratio, remarkably high (Gd/Yb)_n values (&gt;10), and the radiogenic Nd isotopic composition indicate that the dacitic melts were derived from a juvenile mafic source. According to petrogenetic estimations, such conditions could be caused by the partial melting of depleted N-MORB basites in equilibrium with an eclogitic residue. The dacitic magmas were likely generated by the partial melting of mafic rocks at lower levels of the significantly thickened crust (&gt;60 km) in relation to collision processes.</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"32 2","pages":"165 - 178"},"PeriodicalIF":1.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1134/S0869591124020073.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140765319","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":"Serpentine Mineral Association, Texture and Composition as Keys to Serpentine Origin in Kimberlites","authors":"M. G. Kopylova,&nbsp;C. Sismondo,&nbsp;S. Vanderzee","doi":"10.1134/S0869591124020048","DOIUrl":"10.1134/S0869591124020048","url":null,"abstract":"<p>Syn-emplacement serpentine is one of the most abundant late minerals in kimberlites; its multiple generations can be distinguished by various textural positions and parageneses. Composition of the primary kimberlite melt cannot be accurately determined if we do not recognize distinct origins for several textural varieties of serpentine. This study aims to find compositional indicators of the serpentine origin by characterizing millimetre-sized serpentine domains in hypabyssal kimberlites. Serpentine forms as segregations in the groundmass or when serpentine replaces olivine or metasomatized silicate xenoliths. The latter textural variety of serpentine has not been recognized previously; it develops in Si-rich basement xenoliths ranging from basalt to granite. This serpentine is associated with abundant diopside, pectolite, phlogopite and chlorite and less prominent amphibole, hydrogarnet, wollastonite, xonotlite and other rare Ca hydrosilicates. We report petrography and textures of reacted silicate xenoliths in Renard 65, Orapa AK15, BK1, Gahcho Kué 5034 and Jericho kimberlites and provide a global summary of the phase compositions in the xenoliths. This study discovered that NiO content &lt; 0.05 wt %, Al₂O₃ content &gt; 1.3 wt % and MnO &gt; 0.3 wt % in serpentine are clear signs of formation after felsic xenoliths. Serpentine/chlorite replacing olivine always have 1.5–4 wt % more FeO than serpentine after silicate xenoliths. The compositional contrast results from the immobile behaviour of conserved Al, Ni and Mn. The proposed criteria were tested on a pyroclastic kimberlite with an enigmatic origin of round serpentinized clasts overgrown by fibrous clinopyroxene and identified the precursor of these clasts as felsic. We also determined mineralogical characteristics of serpentine parageneses that can be used for reconstruction of the initial xenolith lithology. Serpentine coexists with the more abundant calcic hydrosilicates (hydrogarnet, xonotlite, amphiboles) in reacted mafic xenoliths. There, serpentine and chlorite crystal structures show less ideal stoichiometry indicative of a higher volume of nanometre-scale interstratification with smectites. Serpentine-rich assemblages in reacted xenoliths formed metasomatically at <i>T</i> &lt; 600°C due to skarn-like mass transfer with the host kimberlite that controlled the gain of Ca and Mg and desilication. These metasomatic assemblages are remarkably identical to rodingites. Serpentine production appeared to be limited by the availability of Si in and around silicate xenoliths, but by the H₂O availability in pseudomorphed olivine/monticellite.</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"32 2","pages":"258 - 282"},"PeriodicalIF":1.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140792250","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":"Erratum to: Thermodynamic Model of the Fluid System H2O–CO2–NaCl–CaCl2 at P-T Parameters of the Middle and Lower Crust","authors":"M. V. Ivanov","doi":"10.1134/S0869591123340027","DOIUrl":"10.1134/S0869591123340027","url":null,"abstract":"","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"31 6","pages":"719 - 719"},"PeriodicalIF":1.5,"publicationDate":"2023-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1134/S0869591123340027.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138473056","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":"Erratum to: Age and Isotope-Geochemical Characteristics of Ta, Nb, W, Sn Mineralization Associated with Rare-Metal Granites (Khangilay Ore District, Eastern Transbaikalia)","authors":"E. V. Badanina,&nbsp;L. F. Syritso,&nbsp;A. A. Ivanova,&nbsp;N. G. Rizvanova","doi":"10.1134/S0869591123340015","DOIUrl":"10.1134/S0869591123340015","url":null,"abstract":"","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"31 6","pages":"718 - 718"},"PeriodicalIF":1.5,"publicationDate":"2023-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1134/S0869591123340015.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138473058","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":"Geodynamics of a Breakup of Western Part of the Karelian Craton: Data on 2.1 Ga Mafic Magmatism","authors":"A. V. Samsonov,&nbsp;A. V. Stepanova,&nbsp;E. B. Salnikova,&nbsp;Yu. O. Larionova,&nbsp;A. N. Larionov","doi":"10.1134/S0869591123060085","DOIUrl":"10.1134/S0869591123060085","url":null,"abstract":"<p>Mafic intraplate magmatism is the main source of information about the geodynamics of processes that lead to the breakup of continental blocks. The article discusses geodynamics of the breakup of the Archean supercraton Superia in the Middle Paleoproterozoic. The discussion is based on data on 2.1 Ga magmatism in the Karelian Craton, where mafic igneous rocks of this age are represented by tholeiites of two geochemical types: depleted and enriched. Geochemically close to N-MORB, depleted tholeiites were studied in the Northern Ladoga Region where they form dike swarms at ca. 2111 ± 6 Ma (U-Pb, SIMS, zircon) in the Hatunoiya locality, and pillow lavas and sills in the Lake Maloe Jänisjärvi locality. Enriched tholeiites were studied in the Lake Tulos locality where they form a large swarm of doleritic dikes of age 2118 ± 5 Ma (U-Pb, ID-TIMS, baddeleyite). The results of these studies provide deeper insight into 2.1 Ga mafic magmatism. Depleted tholeiites with N-MORB geochemistry have a wide spatial distribution in the Karelian Craton and could be formed via decompression melting of a depleted asthenospheric mantle, raising melts along the extension zones, and minimal contamination by the Archean crust. According to modelling results, enriched tholeiitic melts probably occurred due to differentiation and crustal contamination of rising depleted tholeiitic melts through more rigid Archean crustal blocks. Data on ca. 2.1 Ga mafic magmatism in the Karelian craton are difficult to explain within the mantle plume rise model, but are consistent with the model of lithosphere extension due to a retreat of a subduction zone in the northeastern margin of the craton, in the Lapland-Kola Ocean at 2.0–2.2 Ga. The intensive thinning and rupture of the Archean continental lithosphere and opening of an oceanic basin at the western margin of the Karelian craton were probably controlled by the suture zone of the junction of Neoarchean and Paleoarchean crustal blocks, traced in the western part of the Karelian craton. An additional factor that led to the ca. 2.1 Ga lithospheric breakup could be a rise of a deep-seated mantle plume in the Hearne craton, neighboring to the Karelian craton in the Archean Superia supercraton.</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"31 6","pages":"581 - 603"},"PeriodicalIF":1.5,"publicationDate":"2023-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138473292","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":"Application of Proxy Minerals for Evaluation of the Oxygen Isotope Composition of Felsic Melts","authors":"E. O. Dubinina,&nbsp;L. Ya. Aranovich","doi":"10.1134/S0869591123060073","DOIUrl":"10.1134/S0869591123060073","url":null,"abstract":"<div><p>The problems associated with the use of quartz and zircon as proxy minerals for the reconstruction of δ¹⁸O values in acidic melts are considered. It is shown that the correction values Δ(<i>Qz</i>–R) and Δ(R–<i>Zrn</i>) used for the reconstructions are not strictly constant and depend on the mineral composition of the rock and the closure temperature of the oxygen isotopic system of the proxy mineral (<i>T</i>_q, <i>T</i>_z–closure temperature of quartz and zircon, respectively). The applicability of quartz was estimated using an equation for Δ(<i>Qz</i>–R) calculation, which takes into account <i>T</i>_q and the mineral composition of rocks. Using the leucogranites of the Raumid massif (South Pamirs) as an example, it was shown that this correction can be approximated by constant value only under definite conditions. The value of Δ(R–<i>Zrn</i>) was estimated using approach based on calculating the weighted average fractionation coefficient and independent estimates Tz using a zirconium thermometer. It was shown for leucogranite porphyries of the Omsukchan trough that this correction for identical rocks varies from 1.3 to 1.9 ‰, unlike Δ(R–<i>Zrn</i>) = 2.1 determined by the dependence on the SiO₂ content (Lackey et al., 2008). The advantages and limitations on the application of quartz and zircon as proxy minerals have been analyzed.</p></div>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"31 6","pages":"664 - 673"},"PeriodicalIF":1.5,"publicationDate":"2023-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1134/S0869591123060073.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138473347","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":"Crystal Size Distribution as a Key to Understanding Protocumulus Evolution in Layered Intrusions: Experiments, Calculations, and Practice of CSD Extraction","authors":"S. N. Sobolev,&nbsp;A. A. Ariskin,&nbsp;G. S. Nikolaev,&nbsp;I. V. Pshenitsyn","doi":"10.1134/S0869591123060097","DOIUrl":"10.1134/S0869591123060097","url":null,"abstract":"<p>The paper provides a review of calculations and experimental approaches to reproducing three types of crystal size distributions (log-linear, bimodal, lognormal CSD) and systematizes publications on CSD data in rocks of ten known layered massifs. For a more detailed discussion, the results for plagiodunite samples from the Yoko-Dovyren massif, northern Baikal region, Russia, harzburgite from the marginal zone of the Monchegorsk pluton, and urtites from the Lovozero intrusion, Murmansk region, Russia, were selected. Possible causes and scenarios for the formation of three types of CSD established for these intrusive objects are presented.</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"31 6","pages":"648 - 663"},"PeriodicalIF":1.5,"publicationDate":"2023-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138473057","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 Crustal Fluid Reservoirs in Ultramafic Cumulates of Kamchatka","authors":"A. G. Simakin,&nbsp;O. Yu. Shaposhikova","doi":"10.1134/S0869591123060036","DOIUrl":"10.1134/S0869591123060036","url":null,"abstract":"<p>Based on published geophysical and petrological data, lower crustal fluid reservoirs have been proposed below the Klyuchevskoy Volcano, expressed as a low <i>V</i>_<i>p</i>/<i>V</i>_<i>s</i> anomaly. A high <i>V</i>_<i>p</i>/<i>V</i>_<i>s</i> anomaly under the proposed fluid reservoir is interpreted as a zone of magma accumulation. The localization of fluids in these reservoirs in the ductile lower crust can vary from isolated inclusions to filling of microfractures over a time scale of several months. Using a simplified poroelastic model, it is shown that the transition in the topology of pore space filled with fluid or melt can provide the observed changes in <i>V</i>_<i>p</i>/<i>V</i>_<i>s</i> in the anomalies of high and low values at a melt content of several vol % and fluid content less than 1 vol %, respectively. In zones of active volcanism, such as the Klyuchevskaya group of volcanoes (KGV), fluid reservoirs are localized in ultramafic cumulates formed during the early high-temperature stage of magma fractionation. Ultramafic xenoliths in the products of eruptions of the KGV and Avachinsky volcanoes, often interpreted as mantle rocks, formed at pressures of about 5 kbar or depths of about 18–20 km in accordance with two-pyroxene geo-thermobarometry and the content of volatiles in melt inclusions in olivine and spinel. When crossing by ascending magmas, the fluid-containing reservoir experiences mechanical failure and injects a certain amount of fluid into the magma, which then captures pieces of crushed magmatic cumulates. The composition of melt inclusions in olivine can reveal records of the magma-fluid interaction.</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"31 6","pages":"705 - 717"},"PeriodicalIF":1.5,"publicationDate":"2023-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138473052","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":"Effects of the Content of Alkalis on Zircon Solubility in Silicate Melts","authors":"A. A. Borisov,&nbsp;A. N. Koshlyakova","doi":"10.1134/S0869591123060048","DOIUrl":"10.1134/S0869591123060048","url":null,"abstract":"<p>The effects of the content of alkalis on zircon solubility in multicomponent model silicate melts was experimentally studied within the temperature range of 1300–1400°C and 1 atm total pressure. It was demonstrated that the addition of Na₂O and K₂O to the melt results in a comparable increase in zircon solubility. The advantages and disadvantages of the parameters describing the effects of the melt composition on zircon solubility are briefly discussed.</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":"31 6","pages":"674 - 680"},"PeriodicalIF":1.5,"publicationDate":"2023-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138473282","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}