Petrology最新文献

{"title":"Late Mesozoic Carbonatite of Central Asia","authors":"A. V. Nikiforov","doi":"10.1134/S0869591123010137","DOIUrl":"10.1134/S0869591123010137","url":null,"abstract":"<div><p>Late Mesozoic carbonatites of Central Asia are developed within the Central Asian Orogenic Belt and adjacent territories of the Siberian and North China platforms. In terms of their structural position, age, geochemical characteristics, and other parameters, they differ from other carbonatite occurrences of Central Asia and are distinguished as the Late Mesozoic carbonatite province in Central Asia. The province includes separate areas of carbonatite magmatism, the geological position of which is determined by the relation with Late Mesozoic rift zones of intracontinental Asia. The carbonatites were formed within a relatively narrow time range (between 150 and 118 Ma) at the early evolution stages of these zones. The carbonatite-bearing complexes of the province are represented by subolcanic and volcanic associations of silicate rocks, carbonatites, magmatic non-silicate rocks (phosphates, sulfates, and others), as well as products of hydrothermal activity. The carbonatites are characterized by diverse composition and include calciocarbonatites, magnesiocarbonatites, and ferrocarbonatites. The silicate rocks are dominated by K–Na and K intermediate rocks. All these rocks have similar geochemical features determined by the elevated contents of LREE, Sr, Ba, and Pb, at low Nb and Ta contents. The typomorphic minerals of carbonatites of the province, in addition to carbonates, are fluorite, Ba and Sr sulfates or carbonates, LREE F-carbonates, and apatite. Unaltered carbonatites are enriched in ¹⁸О and ¹³С relative to mantle values, but in general fall within the compositional range of carbonatites around the world. Hydrothermal and supergene processes modified the mineral composition of carbonatites, which was accompanied by a change of the initial Sr, O, and C isotope composition. The Sr and Nd isotope composition of rocks of carbonatite complexes of the province in general depends on the age of the basement of a definite volcanic area. Carbonatites and associated silicate rocks have close isotope characteristics, but carbonatites usually show relative enrichment in (⁸⁷Sr) and depletion in radiogenic neodymium (¹⁴³Nd). The formation of the Late Mesozoic carbonatite province is related to the activity of mantle plumes, which controlled the Late Mesozoic magmatism in Central Asia. The plumes obviously were accompanied by fluid flows enriched in СО₂, F, and S. This caused the enrichment of lithospheric mantle in volatile components, as well as REE, Sr, Ba, and K, which were extracted by a fluid en route to the surface. Subsequent melting of metasomatized mantle produced parental melts of carbonate-bearing rock complexes.</p></div>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2023-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4541917","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":"Aegirine-Bearing Clinopyroxenes in Granulite Xenoliths from the Udachnaya Kimberlite Pipe, Siberian Craton: Comparison of the Mössbauer and Micropobe Data","authors":"A. V. Sapegina,&nbsp;M. V. Voronin,&nbsp;A. L. Perchuk,&nbsp;O. G. Safonov","doi":"10.1134/S0869591123010083","DOIUrl":"10.1134/S0869591123010083","url":null,"abstract":"<div><p>The aegirine end-member (NaFe³⁺Si₂O₆) in clinopyroxenes resulted from incorporation of Fe³⁺ into the mineral structure. Its presence affects the accuracy of reconstruction of the <i>P-T</i> conditions in the high-grade metamorphic rocks and allows the evaluation of the redox conditions of their formation. The content of this end-member in clinopyroxenes is usually estimated using crystal chemical recalculations of microprobe analyses. However, in some publications on eclogites, the comparison of microprobe-based recalculations with Mössbauer data revealed significant difference between the measured and calculated Fe³⁺/ΣFe ratios, which can significantly affect the results of geothermometry. This paper presents the results of the Mössbauer spectroscopy measurements of clinopyroxene fractions separated from three samples of garnet–clinopyroxene granulites from the Udachnaya kimberlite pipe. The ratios Fe³⁺/ΣFe = 0.22–0.26 measured in the clinopyroxenes correspond to 6–10 mol % aegirine. These estimates are in good agreement with the values obtained for the same clinopyroxenes by the recalculation of microprobe analyses using the charge balance method. Following this conclusion, we believe that crystal chemical recalculations of microprobe analyzes of clinopyroxenes from non-eclogitic rocks make it possible to correctly estimate the Fe³⁺ content in them. Similar recalculation of microprobe analyses of clinopyroxenes in crustal xenoliths from other localities, as well as from ferrobasalts of the continental flood basalts provinces, ferrodolerite dikes, and gabbroid xenoliths (similar in bulk chemical composition to many lower–middle crustal xenoliths) revealed significant amounts of previously unaccounted aegirine (up to 13 and 4–9 mol %, respectively), which holds the potential for deciphering redox conditions in many rocks.</p></div>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4828030","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 Metallogeny of Intrusive Aplite Dyke from the Malanjkhand Pluton, Central India","authors":"Dinesh Pandit","doi":"10.1134/S086959112301006X","DOIUrl":"10.1134/S086959112301006X","url":null,"abstract":"<p>The relationships between textural variations and structural trends of the aplite dyke enclosed in the Malanjkhand pluton were investigated in this study. The estimated zircon saturation temperature (747–835°C) and pressure of crystallization (2.5–6.1 kbar) suggested that the aplite dyke was emplaced in the lower-middle level in the continental crust. Water solubility calculations indicated that the aplite dyke originated from the silicic magma under water undersaturated conditions. Primitive mantle normalized spider diagram showed enrichment of large-ion lithophile elements (LILEs) and depletion of high field strength elements (HFSEs). The aplite dyke displayed LREE-enriched and MREE-depleted patterns, with significant positive Eu-anomaly in the REE patterns. This observation alluded the accumulation of plagioclase crystals before the crystallization of felsic magma in the reduced environment. The presence of the positive Eu-anomaly signified that the pre-existing granitic source at the lower-middle level of the crust generated aplitic magma owing to partial melting above the felsic source rock. Trace element discrimination diagrams presented evidence for possible extensional tectonic settings coupled with felsic magmatic episodes and granitic plutonic activity in a continental rift environment, thus favoring the emplacement of the aplite dyke. Th/U ratios in the aplite dyke implied that the melt fractionation in the magma chamber and the post-magmatic hydrothermal processes exerted negligible effect on the crystallization evolution of the aplitic magma. The aplite dyke pointed to a single pulse of silicic magmatism and a continuous process of injection, thus reflecting subtle variations in the physical conditions of the formation of the host Malanjkhand pluton.</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4830821","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":"Condensate in Impact Glass Samples from the Lonar Crater, India","authors":"T. A. Gornostaeva,&nbsp;A. V. Mokhov,&nbsp;A. P. Rybchuk,&nbsp;P. M. Kartashov","doi":"10.1134/S0869591123010046","DOIUrl":"10.1134/S0869591123010046","url":null,"abstract":"<p>Polycomponent condensate glasses found in nature provide an insight into condensation mechanisms, which are still understood inadequately poorly. Condensate glasses found in the impactites of the Lonar crater contain nanosized inclusions of metallic Fe, Cr, Cu, Zn, Ag, In, Te, Au, Pt, and Bi, along with Fe, Cu, and Zn sulfides. This combination may be indicative either of a brief condensation window for the almost simultaneous condensation of components with so different fugacity or of a possible mechanism of cluster condensation, provided that the condensation temperatures of such clusters are close.</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5130070","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":"Crystallization Parameters, Genesis of Melts, and Sources of Magmas of the Late Cenozoic Udokan Volcanic Plateau, Central Asia","authors":"V. V. Yarmolyuk,&nbsp;V. M. Savatenkov,&nbsp;A. M. Kozlovsky,&nbsp;F. M. Stupak,&nbsp;M. V. Kuznetsov,&nbsp;L. V. Shpakovich","doi":"10.1134/S0869591123010101","DOIUrl":"10.1134/S0869591123010101","url":null,"abstract":"<p>Similar to the other areas of the Late Cenozoic volcanic province of Central Asia, the Udokan volcanic plateau (UVP) was formed in the time span between the Middle Miocene and the Pleistocene. Its rocks are highly alkaline and vary from alkaline picrobasalts and basanites to alkaline trachytes. The compositional variations of the rocks were controlled by two differentiation trends, which corresponded to different generation conditions of the parental magmas. The rocks with low SiO₂ contents (&lt;45 wt %) were formed by melts of low degrees of melting, whose melts were derived under elevated pressures and temperatures. The formation of the rocks with 45–61 wt % SiO₂ was associated with the differentiation of basalt melts, which were derived at shallower depths and at lower temperatures. The geochemical characteristics of the UVP basaltoids make them similar to OIB-type basalts. They are also close in Sr, Nd, and Pb isotopic composition, corresponding to the parameters of the moderately depleted mantle, which is close to the composition of oceanic basalt sources corresponding to the mantle of deep mantle plumes. The corresponding mantle component is present in the sources of other volcanic regions of the Late Cenozoic intraplate volcanic province in Central Asia, which indicates that the material of a lower mantle plume was involved in the formation of these regions.</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4834275","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":"Ti and Cr in High-Pressure Mica: Experimental Study and Application to the Mantle Assemblages","authors":"A. A. Bendeliani,&nbsp;A. V. Bobrov,&nbsp;L. Bindi,&nbsp;N. N. Eremin","doi":"10.1134/S0869591123010113","DOIUrl":"10.1134/S0869591123010113","url":null,"abstract":"<p>Experiments aimed at the synthesis of Cr- and Ti-bearing phlogopite in the silicate-carbonate systems peridotite—K₂CO₃ + H₂O and basalt—K₂CO₃ + H₂O at 7 GPa and 900–1200°С were carried out. It is shown that the crystallization of titanium-bearing phlogopite requires subducted crustal material at mantle depths. However, the mantle peridotite should predominate over basalt for Ti-phlogopite crystallization; otherwise, dioctahedral mica (aluminoceladonite) with (Mg + Fe)/^VIAl &gt; 1 is formed via the scheme 2^VIAl = ^VITi⁴⁺ + ^VI(Mg + Fe). The competitive behavior of Ti and Cr upon incorporation into phlogopite is considered. It is shown that the presence of &gt;1.3 wt % TiO₂ introduces a limitation on the high concentrations of Cr₂O₃ via the scheme ^VI(Mg²⁺) + ^IV(Si⁴⁺) = ^VI(Cr³⁺) + ^IV(Al³⁺). This can explain the compositional patterns of phlogopite from inclusions in natural diamonds, in which the Ti content is much higher than that of Cr. The results obtained support the original idea that the composition of phlogopite may be applied to distinguish the paragenetic associations of diamond.</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4829485","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 Monticellite-bearing Rocks of the Krestovskaya Intrusion: Genesis according to Melt Inclusion Study","authors":"L. I. Panina,&nbsp;A. T. Isakova,&nbsp;E. Yu. Rokosova","doi":"10.1134/S0869591123010071","DOIUrl":"10.1134/S0869591123010071","url":null,"abstract":"<div><p>The investigation of monticellitolites and olivine–monticellite rocks from the Krestovskaya Intrusion shows that the major minerals (olivine and monticellite) have higher MgO content than the same minerals in olivinites and kugdites of the intrusion. In the studied rocks olivine contains 90–93 mol % <i>Fo</i> and monticellite has 41.6–42.3 mol % <i>Fo,</i> whereas olivine and monticellite in olivinites and kugdites contain 86–87 and 37.2–41.2 mol % <i>Fo</i>, respectively. Melt inclusion study in minerals of monticellite rocks demonstrates that the monticellite rocks of the Krestovskaya Intrusion were formed by mixing of volatile-rich melts of different composition: K-rich high-iron low-alumina kamafugitic melt and Na-rich high-magnesium high-alumina picritic melt. Minerals crystallized at high temperatures in the following sequence: perovskite I (1250–1230°C) → perovskite II (≥1200°C) ↔ olivine (&gt;1200°C) → monticellite (&gt;1150°C). Perovskite I in monticellite rocks, as well as olivine in olivinites, crystallized from K-rich high-iron (Mg# = MgO/(MgO + FeO) = 0.37), low-alumina kamafugitic melt. During crystallization of late perovskite II in the monticellite rocks, the melt became more enriched in MgO (Mg# = 0.41) and richer in Na₂O and Al₂O₃, which is intermediate in composition between kamafugite and alkali picrite. Olivine in the monticellite rocks crystallized from melts similar in composition to melilitite, having a K-rich composition with Mg# = 0.39, whereas monticellite formed from a heterogeneous high-Mg Si-undersaturated melt, which is highly enriched with volatile components (including H₂O) and salts. The crystallization of minerals was accompanied by subsequent accumulation of volatile components in mixing melts, silicate–carbonate liquid immiscibility under 1250–1190°C, and polyphase carbonate–salt immiscibility under below 1190°C. In the latter event, the exsolved carbonate melt began to split into simpler immiscible fractions: alkali–sulfate–carbonate, alkali–phosphate–carbonate, and calcio–carbonate.</p></div>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4834277","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":"Staurolite in Metabasites: P–T–X Parameters and the Ratios of Major Components as Criteria of Staurolite Stability","authors":"E. B. Borisova,&nbsp;Sh. K. Baltybaev,&nbsp;J. A. D. Connolly","doi":"10.1134/S0869591123010034","DOIUrl":"10.1134/S0869591123010034","url":null,"abstract":"<p>Fe–Mg staurolite is a typical and widespread mineral of medium-temperature high-alumina metapelites, whereas magnesian staurolite is only relatively rarely found in metamorphosed mafic rocks (metabasites). The most significant factors controlling staurolite stability in metabasites were identified by thermodynamic modeling and analysis of the common features of the mineral-forming processes. In contrast to staurolite in low- and medium-pressure metapelites, staurolite in metabasites is stable at medium- and high-pressure metamorphism. An increase in the proportion of carbon dioxide in the water–carbon dioxide fluid shifts the staurolite-forming mineral reactions to lower temperatures and higher pressures. Al, Fe, Mg, and Ca are the major components of rocks that are critically important for the formation of magnesian staurolite in these rocks, and the contents and ratios of these components are of crucial importance for the stability of staurolite in metabasites. To understand the processes forming the mineral in metabasites, it is instrumental to subdivide metabasites into subgroups of predominantly magnesian, ferruginous–magnesian, and ferruginous protoliths. With regard to this subdivision, three petrochemical modules are proposed in the form of ratios of major components: MgO/CaO, CaO/FM, and Al₂O₃/FM, based on which it is possible to predict the stability of staurolite in mafic rocks at appropriate <i>P–T</i> parameters of metamorphism.</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4829855","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":"Grenville and Valhalla Tectonic Events at the Western Margin of the Siberian Craton: Evidence from Rocks of the Garevka Complex, Northern Yenisei Range, Russia","authors":"I. I. Likhanov","doi":"10.1134/S0869591123010058","DOIUrl":"10.1134/S0869591123010058","url":null,"abstract":"<p>Understanding the tectonic evolution of the Yenisei Range offers important clues not only for the tectonic evolution of orogenic belts at margins of ancient cratons but also for solving the problem of the incorporation of the Siberian craton into the Rodinia supercontinent. Results of mineralogical−petrological, geochemical, and isotope–geochemical studies provide an insight into the petrogenesis, geotectonic settings, thermodynamic parameters of formation, and the ages of the metamorphism and protoliths for the contrastingly compositionally different rocks of the Garevka metamorphic complex. The paper discusses the possible models for the origin of the rock complexes and the geodynamic settings in which they were formed. The western margin of the Siberian craton was determined to have been affected by two pulses of Neoproterozoic endogenic activity, which were related to the origin of the Rodinia supercontinent (930–900 and 880–845 Ma), and which correlated with Grenville and post-Grenville processes responsible for Valhalla folding. The regional geodynamic history is correlated with the coeval sequence and similar style of tectono−thermal events in the peripheries of the large Precambrian cratons Laurentia and Baltica, which is consistent with the proposed Neoproterozoic paleogeographic reconstructions of close spatiotemporal relationships between these cratons and their incorporation into Rodinia configuration.</p>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4830802","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":"Carbonation of Serpentinites of the Mid-Atlantic Ridge: 1. Geochemical Trends and Mineral Assemblages","authors":"S. A. Silantyev,&nbsp;E. A. Krasnova,&nbsp;D. D. Badyukov,&nbsp;A. V. Zhilkina,&nbsp;T. G. Kuzmina,&nbsp;A. S. Gryaznova,&nbsp;V. D. Shcherbakov","doi":"10.1134/S0869591123010095","DOIUrl":"10.1134/S0869591123010095","url":null,"abstract":"<div><p>Abyssal peridotite outcrops compose vast areas of the ocean floor in the Atlantic, Indian, and Arctic Oceans, where they are an indispensable part of the oceanic crust section formed in the slow-spreading oceanic ridges (Mid-Atlantic Ridge, Southwest Indian Ridge, and Gakkel Ridge). The final stage in the evolution of abyssal peridotites in the oceanic crust is their carbonation, which they experience on the ocean floor surface or near it. The main goal of this study was to reconstruct the geochemical trends accompanying the carbonation of abyssal peridotites using MAR ultramafic rocks as an example and to identify the main factors that determine their geochemical and mineralogical differences. The composition variations of rock-forming minerals and their characteristic assemblages indicate that the initial stages of carbonation of abyssal peridotites occurred in crustal conditions simultaneously with the serpentinization of these rocks. The final stage in the crustal evolution of the abyssal peridotites is their exhumation on the ocean floor where they were brought up along the detachment faults. On the ocean floor, the abyssal peridotites in close association with gabbro form oceanic core complexes, and the degree of their carbonation sharply increases with time of their exposure on the ocean floor. The presented data made it possible to qualitatively reconstruct the sequence of events that determined the mineralogical and geochemical features of carbonatized abyssal peridotites of the MAR.</p></div>","PeriodicalId":20026,"journal":{"name":"Petrology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5130083","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}