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Alkali feldspar syenites with shoshonitic affinities from Chhotaudepur area: Implication for mantle metasomatism in the Deccan large igneous province

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Geoscience Frontiers 2014年第2期5卷 261-276页

作者： K.R.Hari n.v.chalapathi rao vikas Swarnkar Guiting Hou School of Studies in Geology and Water Resource Management Pt.Ravishankar Shukla University Centre of Advance Study in Geology Banaras Hindu University Department of Civil Engineering Yugantar Institute of Technology and Management The Key Laboratory of Orogenic Belts and Crustal Evolution Ministry of Education School of Earth and Space Sciences Peking University

Two petrologically distinct alkali feldspar syenite bodies （AFS-1 and AFS-2） from Chhotaudepur area, Deccan Large Igneous Province are reported in the present work. AFS-1 is characterized by hypidio-morphic texture and consists of feldspar （Or55Ab43 to Or25Ab71）, ferro-pargasite/ferro-pargasite horn-blende, hastingsite, pyroxene （Wo47, En5, Fs46）, magnetite and biotite. AFS-2 exhibits panidiomorphic texture with euhedral pyroxene （Wo47-50, En22-39, Fs12e31） set in a groundmass matrix of alkali feldspar （Or99Ab0.77 to Or1.33Ab98）, titanite and magnetite. In comparison to AFS-1, higher elemental concentra-tions of Ba, Sr and PREE are observed in AFS-2. The average peralkaline index of the alkali feldspar syenites is w1 indicating their alkaline nature. variation discrimination diagrams involving major and trace elements and their ratios demonstrate that these alkali feldspar syenites have a shoshonite affinity but emplaced in a within-plate and rifting environment. no evidence of crustal contamination is perceptible in the multi-element primitive mantle normalized diagram as well as in terms of trace elemental ratios. The enrichment of incompatible elements in the alkali feldspar syenites suggests the involvement of mantle metasomatism in their genesis.

关键词： Alkali feldspar syenite Deccan large igneous province Mineralogy Geochemistry Shoshonite Mantle metasomatism

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PGE and isotopic characteristics of Shergol and Suru valley Ophiolites,Western Ladakh:Implications for supra-subduction tectonics along Indus Suture Zone

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Geoscience Frontiers 2021年第3期12卷 473-488页

作者： Irfan Maqbool Bhat Talat Ahmad D.v.Subba rao Srinivasan Balakrishnan n.v.chalapathi rao Department of Earth Sciences University of KashmirSrinagar 190006India vice Chancellors Office University of KashmirSrinagar 190006India Geochemistry Division CSIR-National Geophysical Research Institute(NGRI)Hyderabad 500007India Department of Earth Sciences Pondicherry UniversityPuducherry 605014India Centre of Advanced Study in Geology Institute of ScienceBanaras Hindu UniversityVaranasi 221005India

Present study reports the PGE-geochemistry of mantle peridotites and nd-isotope geochemistry of arc related mafic rocks from the Indus Suture Zone(ISZ),western *** total PGE concentration of the Shergol and Suru valley peridotites(∑PGE=96-180 ppb)is much higher than that of the primitive mantle and global ophiolitic mantle *** studied peridotites show concave upward PGE-distribution patterns with higher palladium-group PGE/Iridium-group PGE ratios(i.e.,0.8-2.9)suggesting that the partial melting is not the sole factor responsible for the evolution of these *** observed PGE-distribution patterns are distinct from residual/refractory mantle peridotites,which have concave downward or flat PGE-distribution *** enrichment of palladium-group PGE as well as other whole-rock incompatible elements(e.g.,LILE and LREE)and higher Pd/Ir ratio(1.1-5.9)reflects that these peridotites have experienced fluid/melt interaction in a supra-subduction zone(SSZ)tectonic ***,the Shergol mafic intrusives and Dras mafic volcanics,associated with the studied peridotites,have high^(143)nd/^(144)nd ratios(i.e.,0.512908-0.513078 and 0.512901-0.512977,respectively)and positiveε_(nd)(t)(calculated for t=140 Ma)values(i.e.,+5.3 to+8.6 and+5.1 to+6.6,respectively),indicating derivation from depleted mantle sources within an intra-oceanic arc setting,similar to Spongtang and nidar ophiolites from other parts of Ladakh *** transition from SSZ-type Shergol and Suru valley peridotites to Early Cretaceous tholeiitic Shergol mafic intrusives followed by tholeiitic to calc-alkaline Dras mafic volcanics within the neo-Tethys Ocean exhibit characteristics of subduction initiation mechanism analogous to the Izu-Bonin-Mariana arc system within western Pacific.

关键词： PGE nd-isotope Mantle peridotites Ophiolites Ladakh neo-Tethys Ocean

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Petrology,genesis and geodynamic implication of the Mesoproterozoic-Late Cretaceous Timmasamudram kimberlite cluster,Wajrakarur field,Eastern Dharwar Craton,southern India

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Geoscience Frontiers 2017年第3期8卷 541-553页

作者： Ashish Dongre n.v.chalapathi rao K.S.viljoen B.Lehmann Department of Geology University of Johannesburg Department of Geology Centre of Advanced StudyBanaras Hindu University Mineral Resources Technical University of Clausthal

new mineralogical and bulk-rock geochemical data for the recently recognised Mesoproterozoic （ca. 1100 Ma） and late Cretaceous （ca. 90 Ma） kimberlites in the Timmasamudram cluster （TKC） of the Wajrakarur kimberlite field （WKF）, Eastern Dbarwar Craton, southern India, are presented. On the basis of groundmass mineral chemistry （phlogopite, spinel, perovskite and clinopyroxene）, bulk-rock chem- istry （SiO2, K20, low TiO2, Ba/nb and La/Sm）, and perovskite nd isotopic compositions, the TI（-1 （mac- rocrystic variety） and TI（-4 （Macrocrystic variety） kimberlites in this cluster are here classified as orangeites （i.e. Group II kimberlites）, with geochemical characteristics that are very similar to orangeites previously described from the Bastar Craton in central India, as well as the Kaapvaal Craton in South Africa. The remaining kimberlites （e.g., TK-2, TK-3 and the TK-1 microcrystic variant）, are more similar to other 1100 Ma, Group l-type kimberlites of the Eastern Dharwar Craton, as well as the typical Group I kimberlites of the Kaapvaal Craton. Through the application of geochemical modelling, based on pub- lished carbonated peridotite/melt trace element partition coefficients, we show that the generation of the TI（C kimberlites and the orangeites results from low degrees of partial melting of a metasomatised, carbonated peridotite. Depleted mantle （TDM） nd perovskite model ages of the 1100 Ma Timmasamudram kimberlites show that the metasomatic enrichment of their source regions are broadly similar to that of the Meso- proterozoic kimberlites of the EDC. The younger, late Cretaceous （ca. 90 Ma） TI（-1 （macrocrystic variant） and TK-4 kimberlites, as well as the orangeites from the 8astar Craton, share similar nd model ages of 1100 Ma, consistent with a similarity in the timing of source enrichment during the amalgamation of Rodinia supercontinent. The presence of late Cretaceous diamondiferous orangeite activity, presumably related to the location of the Marion hotspot

关键词： Kimberlite Orangeite Diamond Timmasamudram Wajrakarur India

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Petrology and Sr-nd isotope systematics of the Ahobil kimberlite(Pipe-16)from the Wajrakarur field, Eastern Dharwar craton, southern India

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Geoscience Frontiers 2019年第3期10卷 1167-1186页

作者： Abhinay Sharma Alok Kumar Praveer Pankaj Dinesh Pandit Ramananda Chakrabarti n.v.chalapathi rao EPMA and SEM Laboratories Department of Geology Banaras Hindu University Centre for Earth Sciences Indian Institute of Science

Detailed mineralogical, bulk-rock geochemical and Sr-nd isotopic data for the recently discovered Ahobil kimberlite(Pipe-16) from the Wajrakarur kimberlite field(WKF), Eastern Dharwar craton(EDC),southern India, are presented. Two generations of compositionally distinct olivine, Ti-poor phlogopite showing orangeitic evolutionary trends, spinel displaying magmatic trend-1, abundant perovskite, Tirich hydrogarnet, calcite and serpentine are the various mineral constituents. On the basis of(i) liquidus mineral composition,(ii) bulk-rock chemistry, and(iii) Sr-nd isotopic composition, we show that Ahobil kimberlite shares several characteristic features of archetypal kimberlites than orangeites and lamproites. Geochemical modelling indicate Ahobil kimberlite magma derivation from small-degree melting of a carbonated peridotite source having higher Gd/Yb and lower La/Sm in contrast to those of orangeites from the Eastern Dharwar and Bastar cratons of Indian shield. The T_(Dm) nd model age(～2.0 Ga) of the Ahobil kimberlite is(i) significantly older than those(1.5～1.3 Ga) reported for Wajrakarur and narayanpet kimberlites of EDC,(ii) indistinguishable from those of the Mesoproterozoic EDC lamproites,and(iii) strikingly coincides with the timing of the amalgamation of the Columbia supercontinent. High bulk-rock Fe-Ti contents and wide variation in oxygen fugacity fO_2, as inferred from perovskite oxybarometry, suggest non-prospective nature of the Ahobil kimberlite for diamond.

关键词： Petrology Isotopes Kimberlite Wajrakarur Dharwar craton India

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Petrogenesis of the crater-facies Tokapal kimberlite pipe,Indrvati Basin,Central India

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Geoscience Frontiers 2014年第6期5卷 781-790页

作者： n.v.chalapathi rao B.Lehmann B.K.Panwar Alok Kumar D.Mainkar Department of Geology Centre of Advanced StudyBanaras Hindu UniversityVaranasi 221005India Mineral Resources Technical University of Clausthal38678 Clausthal-ZellerfeldGermany Directorate of Geology and Mining RaipurChhattisgarh 492007India

new geochemical data of the crater-facies Tokapal kimberlite system sandwiched between the lower and upper stratigraphic horizons of the Mesoproterozoic lndravati Basin a：：e presented. The kimberlite has been subjected to extensive and pervasive low-temperature alteration. Spinel is the only primary phase identifiable, while olivine macrocrysts and juvenile lapilli are largely pseudomorphed （talc-serpentine- carbonate alteration）. However, with the exception of the alkalies, major element oxides display systematic fractionation trends; likewise, HFSE patterns are well correlated and allow petrogenetic interpretation. various crustal contamination indices such as （SiO2 ＋ AI：：O3 ~ na20）]（MgO ~ K20） and Si] Mg are close to those of uncontaminated kimberlites. Similar La]Yb （＇79-109） of the Tokapal samples with those from the kimberlites of Wajrakarur （73-145） and narayanpet （72-156）, Eastern Dharwar craton, southern India implies a similarity in their genesis. In the discriminant plots involving HFSE the Tokapal samples display strong affinities to Group 1I kimberlites from southern Africa and central India as well as to ＇transitional kimberlites＇ from the Eastern Dharwar craton, southern India, and those from the Prieska and Kuruman provinces of southern Africa. There is a striking ~;imilarity in the depleted-mantle （TOM） nd model ages of the Tokapal kimberlite system, Bastar craton, th~ kimberlites from nKF and WKE Eastern Dharwar craton, and the Majhgawan diatreme, Bundelkhand craton, with the emplacement age of some of the lamproites from within and around the Palaeo^Mesoproterozoic Cuddapah basin, southern India. These similar ages imply a major tectonomagmatic event, possibly related to the break- up of the supercontinent of Columbia, at 1.3-1.5 Ga across the l：hree cratons. The ＇transitional＇ geochemical features displayed by many of the Mesoproterozoic po~：assic-ultrapotassic rocks, across these Indian cratons are inferred to be memories of the metasomatising f

关键词： Kimberlite Tokapal Columbia Bastar craton India

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Rift-associated ultramafic lamprophyre(damtjernite) from the middle part of the Lower Cretaceous(125 Ma) succession of Kutch,northwestern India: Tectonomagmatic implications

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Geoscience Frontiers 2018年第6期9卷 1883-1902页

作者： Rohit PAnDey n.v.chalapathi rao Prashant Dhote Dinesh PAnDit A.K.Choudhary Samarendra Sahoo B.Lehmann Electron Probe Micro Analyzer Laboratory Department of Geology Centre of Advanced Study Banaras Hindu University Bhumi Geoservices 1 & 2 Maa Bamleshwari Nagar Godhani Railway Institute Instrumentation Centre Indian Institute of Technology Mineral Resources Technical University of Clausthal

Mineralogical,geochemical and isotopic(Sr and nd) studies on the recently reported ca. 124 Ma'anorogenic lamproite' dyke from the Palanpur area, Kutch seismogenic rift zone, northwestern India, are presented. We propose a new classification for the dyke as a damtjernite(ultramafic lamprophyre; UML)based on its porphyritic-panidiomorphic texture, abundance of phlogopite, presence of nepheline in the groundmass, and the composition of liquidus phases such as olivine, phlogopite, magnetite, and clinopyroxene(diopside). The Palanpur UML is primitive(Mg# =74-77),silica-undersaturated(SiO_2n nature, and is strikingly similar to the ～69 Ma UML dykes and sills of the Tethyan Indus suture zone, which are considered as the earliest yet known manifestations of the Deccan Large Igneous Province(LIP). Bulk-rock(^(87)Sr/^(86)Sr)_i(0.70460-0.70461) and ε_(n)d(t)(+2.56 to-0.69) of the Palanpur UML signify derivation from a slightly depleted mantle source similar to that of asthenospheric magmas such as OIB. This is further attested to by the high incompatible trace element ratios(viz., La/Ba, nb/U, nb/La and Ta/Yb) that are typical of plume-type magmas. However, the neoproterozoic T_(DM) depleted mantle nd model ages( ～655-919 Ma) also necessitate some involvement of a lithospheric mantle component in its genesis. High bulk-rock Fe_2 O_3~t and TiO_2 contents require the involvement of a fertile peridotitic mantle source, whereas high La/Yb(60-80) implies a control by residual garnet. Higher Rb/Sr and lower Ba/Rb suggest phlogopite as a residual phase and high nb and lower La/Sm favour carbonatite, rather than silicate melt as metasomatising agent. Low degrees of partial melting of a primitive garnet lherzolite mantle can account for the observed REE patterns in the Palanpur UML. The Palanpur UML shares a temporal similarity to the Kerguelen plume-derived Rajmahal basalts and associated alkaline rocks from the eastern India. The tectonomagmatic

关键词： Tectonomagmatism Cretaceous Ultramafic lamprophyre Rift Kutch India

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Dendritic spine degeneration:a primary mechanism in the aging process

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neural Regeneration Research 2025年第6期20卷 1696-1698页

作者： Gonzalo Flores Leonardo Aguilar-Hernández Fernado García-Dolores Humberto nicolini Andrea Judith vázquez-Hernández Hiram Tendilla-Beltrán Instituto de Fisiología Benemérita Universidad Autónoma de Puebla(BUAP)PueblaMexico Instituto de Ciencias Forenses(InCIFO) Tribunal Superior de Justicia de la Ciudad de México(TSJCDMX).Mexico CityMexico Instituto nacional de Medicina Genómica(InMEGEn) Mexico CityMexico

Recent reports suggest that aging is not solely a physiological process in living beings;instead, it should be considered a pathological process or disease(Amorim et al., 2022). Consequently, this process involves a wide range of factors, spanning from genetic to environmental factors, and even includes the gut microbiome(GM)(Mayer et al., 2022). All these processes coincide at some point in the inflammatory process, oxidative stress, and apoptosis, at different degrees in various organs and systems that constitute a living organism(Mayer et al., 2022;AguilarHernández et al., 2023).

关键词： aging process stress

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Superconducting magnetic energy storage for stabilizing grid integrated with wind power generation systems

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Journal of Modern Power Systems and Clean Energy 2019年第2期7卷 400-411页

作者： Poulomi MUKHERJEE v. v. rao Applied Superconductivity Laboratory Cryogenic Engineering Centre Indian Institute of TechnologyKharagpur

Due to the interconnection of various renewable energies and adaptive technologies, voltage quality and frequency stability of modern power systems are becoming erratic. Superconducting magnetic energy storage(SMES),for its dynamic characteristic, is very efficient for rapid exchange of electrical power with grid during small and large disturbances to address those *** addition,SMES plays an important role in integrating renewable sources such as wind generators to power grid by controlling output power of wind plant and improving the stability of power *** application of SMES in various power system operations depends on the proper location in the power system, exact energy and power ratings and appropriate controllers. In this paper, an effort is given to explain SMES device and its controllability to mitigate the stability of power grid integrated with wind power generation systems.

关键词： Power fluctuation Power quality Low voltage ride through Superconducting magnetic energy storage Superconductors Wind energy

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An improved analytical model of 4H-SiC MESFET incorporating bulk and interface trapping effects

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Journal of Semiconductors 2015年第1期36卷 64-75页

作者： M.Hema Lata rao n.v.L.narasimha Murty School of Electrical Sciences IIT BhubaneswarBhubaneswar 751013India

An improved analytical model for the current–voltage（I–v） characteristics of the 4H-SiC metal semiconductor field effect transistor（MESFET） on a high purity semi-insulating（HPSI） substrate with trapping and thermal effects is presented. The 4H-SiC MESFET structure includes a stack of HPSI substrates and a uniformly doped channel layer. The trapping effects include both the effect of multiple deep-level traps in the substrate and surface traps between the gate to source/drain. The self-heating effects are also incorporated to obtain the accurate and realistic nature of the analytical model. The importance of the proposed model is emphasised through the inclusion of the recent and exact nature of the traps in the 4H-SiC HPSI substrate responsible for substrate *** analytical model is used to exhibit DC I–v characteristics of the device with and without trapping and thermal effects. From the results, the current degradation is observed due to the surface and substrate trapping effects and the negative conductance introduced by the self-heating effect at a high drain voltage. The calculated results are compared with reported experimental and two-dimensional simulations（Silvaco -TCAD）. The proposed model also illustrates the effectiveness of the gate–source distance scaling effect compared to the gate–drain scaling effect in optimizing 4H-SiC MESFET performance. Results demonstrate that the proposed I–v model of 4H-SiC MESFET is suitable for realizing SiC based monolithic circuits（MMICs） on HPSI substrates.

关键词： SiC MESFET HPSI substrate deep-level traps MMICs

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Microstructure, properties and hot workability of M300 grade maraging steel

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Defence Technology（防务技术） 2018年第1期14卷 51-58页

作者： K.v.A.Chakravarthi n.T.B.n.Koundinya S.v.S.narayana Murty B.nageswara rao Materials and Mechanical Entity Vikram Sarabhai Space Centre Research scholar Department of Mechanical Engineering K L University Department of Metallurgical Engineering and Materials Science Indian Institute of Technology Department of Mechanical Engineering K L University

This paper presents isothermal uniaxial compression test results of M300 grade maraging steel over a wide range of temperatures(900 e1200℃) and strain rates(0.001 e100 s^(-1)) to examine hot deformability and concurrent microstructural evolution. Processing map is generated and indicated the optimum processing parameters in the temperature range of 1125℃-1200℃ and strain rate range of 0.001 e0.1 s^(-1). High values of the efficiency of power dissipation, microstructural observations and EBSD results indicate softening mechanism to be the occurrence of dynamic recrystallisation. Material constants in a constitutive relation are evaluated from the flow stress data useful in computer modelling.

关键词： Activation energy Constitutive relation Hot deformation M300 grade maraging steel Processing map

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