Large-scale Danian-age(post-K/Pg boundary)Deccan magmatism is well known from the Mumbai metropolitan area,located in the structurally complex Panvel flexure zone along the western Indian rifted continental margin.Thi...Large-scale Danian-age(post-K/Pg boundary)Deccan magmatism is well known from the Mumbai metropolitan area,located in the structurally complex Panvel flexure zone along the western Indian rifted continental margin.This compositionally diverse late-Deccan magmatic suite contains subaerial tholeiitic lavas and dykes typical of the main Deccan province,with many features atypical of the Deccan,such as spilitic pillow lavas,“intertrappean”sediments(often containing considerable volcanic ash),rhyolitic lavas and tuffs,gabbro-granophyre intrusions,and trachyte intrusions containing alkali basalt enclaves.Most of these units,previously dated at 62.5 Ma to 61 Ma,are contemporaneous with or slightly postdate the 62.5 Ma India-Seychelles continental breakup and Panvel flexure formation.In the Dongri-Uttan area,two samples of a>50-m-thick,columnar-jointed rhyolite from the Darkhan Quarry and from a section behind the current Uttan Sagari Police Station have previously been dated at 62.6±0.6 Ma and 62.9±0.2 Ma(^(40)Ar/^(39)Ar,2r errors).New exposures reveal that these two statistically indistinguishable 40 Ar/39 Ar ages correspond to two distinct rhyolite units,separated by well-bedded silicic ash.The columnar rhyolites are microcrystalline,composed of quartz and alkali feldspar,with rare small(1–2 mm),altered feldspar phenocrysts,and no recognisable relict vitroclasts.Given the westerly structural dip,most of their lateral extent is submerged under the Arabian Sea,and we consider them to be possible flood rhyolite lavas.We interpret the ash beds,composed of pumice clasts and glass shards,as a low-grade(nonwelded)vitric ash,derived from a possibly distal Plinian eruption and deposited by fallout.The lavas and ash are peraluminous rhyolites.The lavas are Sr-Ba-poor and Rb-Zr-Nb-rich,and show“seagull-shaped”rare earth element patterns with deep negative europium anomalies.These crystal-poor lavas are“hot-dry-reduced”rhyolites typical of intraplate,continental rift and rifted margin settings.The very different high-field strength element contents of the lavas and the ash indicate compositionally distinct magma batches.The 62.5 Ma Dongri-Uttan sequence provides clear evidence for rapid silicic eruptions of effusive and explosive nature,alternating with each other and sourced from distinct magma chambers and eruptive vents.A newly identified,highly feldspar-phyric trachyte intrusion marks the last phase of magmatic activity in the area,corresponding with late-stage trachyte-syenite intrusions exposed in coastal western India and the Seychelles,and shows that the Mumbai rhyolites and trachytes form a compositional continuum.展开更多
Cold seeps are oases for biological communities on the sea floor around hydrocarbon emission pathways.Microbial utilization of methane and other hydrocarbons yield products that fuel rich chemosynthetic communities at...Cold seeps are oases for biological communities on the sea floor around hydrocarbon emission pathways.Microbial utilization of methane and other hydrocarbons yield products that fuel rich chemosynthetic communities at these sites.One such site in the cold seep ecosystem of Krishna-Godavari basin(K-G basin)along the east coast of India,discovered in Feb 2018 at a depth of 1800 m was assessed for its bacterial diversity.The seep bacterial communities were dominated by phylum Proteobacteria(57%),Firmicutes(16%)and unclassified species belonging to the family Helicobacteriaceae.The surface sediments of the seep had maximum OTUs(operational taxonomic units)(2.27×10^(3))with a Shannon alpha diversity index of 8.06.In general,environmental parameters like total organic carbon(p<0.01),sulfate(p<0.001),sulfide(p<0.05)and methane(p<0.01)were responsible for shaping the bacterial community of the cold seep ecosystem in the K-G Basin.Environmental parameters play a significant role in changing the bacterial diversity richness between different cold seep environments in the oceans.展开更多
Thirty-six medicinal plant species belonging to 25 families were surveyed to study Arbuscular mycorrhizal （AM） fungal diversity from different localities of North and South Goa of Western Ghats, Goa region, India. A...Thirty-six medicinal plant species belonging to 25 families were surveyed to study Arbuscular mycorrhizal （AM） fungal diversity from different localities of North and South Goa of Western Ghats, Goa region, India. A total of 30 medicinal plant species were found to be mycorrhizal and six plant species showed absence of AM fungal colonization. Forty two AM fungal species belonging to five genera viz., Glomus, Acaulospora, Scutellospora, Gigaspora and Ambispora were recovered from the rhizosphere soil. Glomus was found to be the most dominant genera in the study sites, and Glomus fasciculatum the most dominant AM fungal species. Negative significant correlation was observed between percent colonization and spore density. Simpson＇s and Shannon Weiner diversity index studies carried out in North and South Goa exhibited less variation in both the sites, indicating a stable and a diverse plant community.展开更多
Seventeen mangrove species of eight families at seven river- ine and fringe habitats in Goa West India were surveyed for Arbuscular Mycorrhizal （AM） fungal diversity. Sixteen species were found to be mycorrhizal and...Seventeen mangrove species of eight families at seven river- ine and fringe habitats in Goa West India were surveyed for Arbuscular Mycorrhizal （AM） fungal diversity. Sixteen species were found to be mycorrhizal and one species showed no AM fungal colonization. AM root colonization was recorded at all seven sites and ranged from 6%-77%. Maximum root colonization was recorded in Excoecaria agal- locha （77%） and minimum colonization in Avicennia marina （6%）. Paris-type colonization was predominant at all sites. Auxiliary cells were recorded in roots of Acanthus ilicifolius, Ceriops tagal and Sonneretia alba. AM fungal root colonization and spore density varied by plant species and site. Site average spore density ranged from 1.84 spores.g^-1 to 0.54 spores.g-1 of soil. In total, 28 AM fungal species of five genera, viz. Glomus, Acaulospora, Scutellospora, Gigaspora and Entrophospora, were recovered. Glomus was the dominant genus, three species of which were sporocarpic forms. Maximum site species richness （SR） ranged from 16 to 5. Species richness was maximum in A. ilicifolius where seven species of three genera were recovered. Based on relative abun- dance （RA） and isolation frequency （IF）, two common species, viz. G. intraradices and A. laevis, were recovered from all seven sites.展开更多
The Precambrian greywacke of Ribandar-Chimbel belonging to the Sanvordem Formation of the Goa Group, India, has been studied for petrography and analyzed for major trace elements. The greywacke is characterized by ang...The Precambrian greywacke of Ribandar-Chimbel belonging to the Sanvordem Formation of the Goa Group, India, has been studied for petrography and analyzed for major trace elements. The greywacke is characterized by angular to sub-round grains of quartz, feldspar, biotite, chlorite and clay minerals. The abundance of clay in the matrix seems to have influenced the Al2O3 content and the K20/Al2O3 ratio. The variation diagrams indicate a decreasing trend of TiO2, Al2O3, Fe2O3 and MgO; whereas Na2O and CaO exhibit a scatter which could be a result of the variable presence of feldspar within the sediments. The immobile elements, vanadium （25 to 144 ppm）, nickel （up to 107 ppm） and chromium （up to 184 ppm）, reflect abundance of clay minerals. The greywacke shows strongly fractionated REE patterns with LaN/YbN = 8 to 26 and with higher total REE abundances （up to 245 ppm）. The low REE enrichment and depletion in heavier REE with prominent negative Eu anomaly （Eu/Eu^＊= 0.54 to 0.79） suggest a derivation of the greywacke from an old upper continental crust composed chiefly of felsic components. Petrological evidence and geochemical data suggest that the deposition of the greywacke largely took place in a deep to shallow basin that progressively chang- ed from that of a continental island arc to an active continental setting.展开更多
Emotion recognition is a growing field that has numerous applications in smart healthcare systems and Human-Computer Interaction(HCI).However,physical methods of emotion recognition such as facial expressions,voice,an...Emotion recognition is a growing field that has numerous applications in smart healthcare systems and Human-Computer Interaction(HCI).However,physical methods of emotion recognition such as facial expressions,voice,and text data,do not always indicate true emotions,as users can falsify them.Among the physiological methods of emotion detection,Electrocardiogram(ECG)is a reliable and efficient way of detecting emotions.ECG-enabled smart bands have proven effective in collecting emotional data in uncontrolled environments.Researchers use deep machine learning techniques for emotion recognition using ECG signals,but there is a need to develop efficient models by tuning the hyperparameters.Furthermore,most researchers focus on detecting emotions in individual settings,but there is a need to extend this research to group settings aswell since most of the emotions are experienced in groups.In this study,we have developed a novel lightweight one dimensional(1D)Convolutional Neural Network(CNN)model by reducing the number of convolution,max pooling,and classification layers.This optimization has led to more efficient emotion classification using ECG.We tested the proposed model’s performance using ECG data from the AMIGOS(A Dataset for Affect,Personality and Mood Research on Individuals andGroups)dataset for both individual and group settings.The results showed that themodel achieved an accuracy of 82.21%and 85.62%for valence and arousal classification,respectively,in individual settings.In group settings,the accuracy was even higher,at 99.56%and 99.68%for valence and arousal classification,respectively.By reducing the number of layers,the lightweight CNNmodel can process data more quickly and with less complexity in the hardware,making it suitable for the implementation on the mobile phone devices to detect emotions with improved accuracy and speed.展开更多
Hydrous Cr-bearing uvarovite garnets are rare in natural occurrences and belong to the ugrandite series and exist in binary solid solutions with grossular and andradite garnets. Here, we report the occurrence of hydro...Hydrous Cr-bearing uvarovite garnets are rare in natural occurrences and belong to the ugrandite series and exist in binary solid solutions with grossular and andradite garnets. Here, we report the occurrence of hydrous uvarovite garnet having Cr_(2)O_(3) upto 19.66 wt% and CaO of 32.12–35.14 wt% in the serpentinized mantle peridotites of Naga Hills Ophiolite(NHO), India. They occur in association with low-Cr diopsides. They are enriched in LILE(Ba, Sr), LREEs, with fractionating LREE-MREE [avg.(La/Sm)_(N) = 2.16] with flat MREE/HREE patterns [avg.(Sm/Yb)_(N) = 0.95]. Raman spectra indicate the presence of hydroxyl(OH^(–)) peaks from 3500 to 3700 cm^(-1). Relative abundances in fluid mobile elements and their close association with clinopyroxenes are suggestive of the formation of uvarovite garnets through low temperature metasomatic alteration of low-Cr diopsides by hydrothermal slab fluids. The high LREE concentration and absence of Eu anomaly in the garnet further attest to alkaline nature of the transporting slab dehydrated fluid rather the involvement of low-p H solution. The chemical characteristics of the hydroxyl bearing uvarovite hosted by the mantle peridotite of NHO deviate from the classical features of uvarovite garnet, and their origin is attributed to the fluid-induced metasomatism of the sub arc mantle wedge in a suprasubduction zone regime.展开更多
This study reports major, trace, rare earth and platinum group element compositions of lava flows from the Vempalle Formation of Cuddapah Basin through an integrated petrological and geochemical approach to address ma...This study reports major, trace, rare earth and platinum group element compositions of lava flows from the Vempalle Formation of Cuddapah Basin through an integrated petrological and geochemical approach to address mantle conditions, magma generation processes and tectonic regimes involved in their formation. Six flows have been identified on the basis of morphological features and systematic three-tier arrangement of vesicular-entablature-colonnade zones. Petrographically, the studied flows are porphyritic basalts with plagioclase and clinopyroxene representing dominant phenocrystal phases.Major and trace element characteristics reflect moderate magmatic differentiation and fractional crystallization of tholeiitic magmas. Chondrite-normalized REE patterns corroborate pronounced LREE/HREE fractionation with LREE enrichment over MREE and HREE. Primitive mantle normalized trace element abundances are marked by LILE-LREE enrichment with relative HFSE depletion collectively conforming to intraplate magmatism with contributions from sub-continental lithospheric mantle(SCLM) and extensive melt-crust interaction. PGE compositions of Vempalle lavas attest to early sulphur-saturated nature of magmas with pronounced sulphide fractionation, while PPGE enrichment over IPGE and higher Pd/Ir ratios accord to the role of a metasomatized lithospheric mantle in the genesis of the lava flows. HFSEREE-PGE systematics invoke heterogeneous mantle sources comprising depleted asthenospheric MORB type components combined with plume type melts. HFSE-REE variations account for polybaric melting at variable depths ranging from garnet to spinel lherzolite compositional domains of mantle. Intraplate tectonic setting for the Vempalle flows with P-MORB affinity is further substantiated by(i) their origin from a rising mantle plume trapping depleted asthenospheric MORB mantle during ascent,(ii) interaction between plume-derived melts and SCLM,(iii) their rift-controlled intrabasinal emplacement through Archeane Proterozoic cratonic blocks in a subduction-unrelated ocean-continent transition zone(OCTZ). The present study is significant in light of the evolution of Cuddapah basin in the global tectonic framework in terms of its association with Antarctica, plume incubation, lithospheric melting and thinning, asthenospheric infiltration collectively affecting the rifted margin of eastern Dharwar Craton and serving as precursors to supercontinent disintegration.展开更多
AMnO3 （A=Sr, Sm and Nd） manganites with perovskite structure, prepared by combustion method were characterized by X-ray diffraction （XRD）, infra-red spectroscopy, Brunauer-Emmett-Teller （BET） surface area analyz...AMnO3 （A=Sr, Sm and Nd） manganites with perovskite structure, prepared by combustion method were characterized by X-ray diffraction （XRD）, infra-red spectroscopy, Brunauer-Emmett-Teller （BET） surface area analyzer and scanning electron microscopy （SEM）. The solid state and spectroscopic studies such as electrical resistivity, magnetic susceptibility, electron spin resonance （ESR） and diffuse reflectance spectroscopy were carried out and attempted to correlate with the catalytic activities of the compounds. To evaluate the catalytic activity, a model reaction of CO oxidation over these compounds was undertaken. An attempt was made to understand the effect of A-site change by different metal cations in the manganite perovskites on solid state and catalytic properties.展开更多
The ophiolite suite from south Andaman Islands forms part of the Tethyan Ophiolite Belt and preserves the remnants of an ideal ophiolite sequence comprising a basal serpentinized and tectonised mantle peridotite follo...The ophiolite suite from south Andaman Islands forms part of the Tethyan Ophiolite Belt and preserves the remnants of an ideal ophiolite sequence comprising a basal serpentinized and tectonised mantle peridotite followed by ultramafic and mafic cumulate units, basaltic dykes and spilitic pillow basalts interlayered with arkosic wacke. Here, we present new major, trace, rare earth(REE) and platinum group(PGE) element data for serpentinized and metasomatized peridotites(dunites) exposed in south Andaman representing the tectonized mantle section of the ophiolite suite. Geochemical features of the studied rocks, marked by Al_2 O_3/TiO_2 > 23, LILE-LREE enrichment, HFSE depletion, and U-shaped chondrite-normalized REE patterns with(La/Sm)N > 1 and(Gd/Yb)N <1, suggest contributions from boninitic mantle melts. These observations substantiate a subduction initiation process ensued by rapid slab roll-back with extension and seafloor spreading in an intraoceanic fore-arc regime. The boninitic composition of the serpentinized peridotites corroborate fluid and melt interaction with mantle manifested in terms of(i) hydration, metasomatism and serpentinization of depleted, MORB-type, sub-arc wedge mantle residual after repeated melt extraction; and(ii) refertilization of refractory mantle peridotite by boninitic melts derived at the initial stage of intraoceanic subduction. Serpentinized and metasomatized mantle dunites in this study record both MOR and intraoceanic arc signatures collectively suggesting suprasubduction zone affinity. The elevated abundances of Pd(4.4-12.2 ppb) with highΣPPGE/∑IPGE(2-3) and Pd/Ir(2-5.5) ratios are in accordance with extensive melt-rock interaction through percolation of boninitic melts enriched in fluid-fluxed LILE-LREE into the depleted mantle after multiple episodes of melt extraction. The high Pd contents with relatively lower Ir concentrations of the samples are analogous to characteristic PGE signatures of boninitic magmas and might have resulted by the infiltration of boninitic melts into the depleted and residual mantle wedge peridotite during fore-arc extension at the initial stage of intraoceanic subduction. The PGE patterns with high Os + Ir(2-8.6 ppb)and Ru(2.8-8.4 ppb) also suggest mantle rejuvenation by infiltration of melts derived by high degree of mantle melting. The trace, REE and PGE data presented in our study collectively reflect heterogeneous mantle compositions and provide insights into ocean-crust-mantle interaction and associated geochemical cycling within a suprasubduction zone regime.展开更多
The Naga Hills Ophiolite(NHO)belt in the Indo-Myanmar range(IMR)represents a segment of Tethyan oceanic crust and upper mantle that was involved in an eastward convergence and collision of the Indian Plate with the Bu...The Naga Hills Ophiolite(NHO)belt in the Indo-Myanmar range(IMR)represents a segment of Tethyan oceanic crust and upper mantle that was involved in an eastward convergence and collision of the Indian Plate with the Burmese Plate during the Late Cretaceous-Eocene.Here,we present a detailed petrological and geochemical account for the mantle and crustal sections of NHO,northeastern India to address(i)the mantle processes and tectonic regimes involved in their genesis and(ii)their coherence in terms of the thermo-tectonic evolution of Tethyan oceanic crust and upper mantle.The NHO suite comprises well preserved crustal and mantle sections discretely exposed at Moki,Ziphu,Molen,Washelo and Lacham areas.The ultramafic-mafic lithologies of NHO are mineralogically composed of variable proportions of olivine,orthopyroxene,clinopyroxene and plagioclase.The primary igneous textures for the mantle peridotites have been overprinted by extensive serpentinisation whereas the crustal section rocks reflect crystal cumulation in a magma chamber.Chondrite normalised REE profiles for the cumulate peridotite-olivine gabbro-gabbro assemblage constituting the crustal section of NHO show flat to depleted LREE patterns consistent with their generation from depleted MORB-type precursor melt in an extensional tectonic setting,while the mantle peridotites depict U-shaped REE patterns marked by relative enrichment of LREE and HREE over MREE.These features collectively imply a dual role of depleted MORB-type and enriched arc-type mantle components for their genesis with imprints of melt-rock and fluid-rock interactions.Tectonically,studied lithologies from NHO correspond to a boninitic to slab-proximal Island Arc Tholeiite affinity thereby conforming to an intraoceanic supra subduction zone(SSZ)fore-arc regime coherent with the subduction initiation process.The geochemical attributes for the crustal and mantle sections of NHO as mirrored by Zr/Hf,Zr/Sm,Nb/Ta,Zr/Nb,Nb/U,Ba/Nb,Ba/Th,Ba/La and Nd/Hf ratios propound a two-stage petrogenetic process:(i)a depleted fore arc basalt(FAB)type tholeiitic melt parental to the crustal lithologies was extracted from the upwelling asthenospheric mantle at SSZ fore-arc extensional regime thereby rendering a refractory residual upper mantle;(ii)the crust and upper mantle of the SSZ fore arc were progressively refertilised by boninitic melts generated in response to subduction initiation and slab-dehydration.The vestiges of Tethyan oceanic lithosphere preserved in NHO represent an accreted intra-oceanic fore arc crust and upper mantle section which records a transitional geodynamic evolution in a SSZ regime marked by subduction initiation,fore arc extension and arc-continent accretion.展开更多
This study presents new major,trace and REE data for thirty-five ferromanganese nodules recovered from areas representing three different sediment types(siliceous,red clay and their transition zone)in the Central Indi...This study presents new major,trace and REE data for thirty-five ferromanganese nodules recovered from areas representing three different sediment types(siliceous,red clay and their transition zone)in the Central Indian Ocean Basin(CIOB)to address their genetic aspects,classification,growth rate,nature of host sediments and influence of REE in the processes of nodule formation.The nodules from CIOB are mostly either hydrogenetic(metals coming from oxygenated bottom water)and diagenetic(metals coming from suboxic sediment pore water)or a combination of both,depending on the source of supply of metal.However,a number of biogeochemical processes mediate this supply of metals which again changes from time to time,making the nodule growth process highly dynamic.This study suggests that at the initial stage of nodule growth,host sediments do not play much role in controlling the growth processes for which REEs can enter both Mn and Fe oxyhydroxide phases equally.Thus,the bottom water signature is imprinted in these early formed nodules irrespective of their host sediment substrate but with gradual growth and burial in the sediment,the main mode of metal enrichment becomes diagenetic through sediment pore water.This tends to increase the concentration of Mn,Ni and Cu over other elements which are retained in the sediment fraction.Among the REEs,Ce concentration of the nodules shows significant positive anomaly due to variation in redox potential and hence its magnitude can be used to get an idea about the metal enrichment procedure and the genetic type of the nodules.However,based on host sediment only,not much difference is found in the magnitude of Ce anomaly in these nodules.On the other hand,discrimination diagram,based on HFSE and REY chemistry,indicates that most of these nodules are of diagenetic origin under oxic condition with a trend towards hydrogenetic field.Further,the genetic type of the ferromanganese nodules from the CIOB are more effectively differentiated by a combination of their major and trace element concentrations rather than solely based on their REE or HFSE chemistry or host sediment substrate.展开更多
In paleogeographic reconstructions of the Columbia and Rodinia Supercontinents,the position of the Greater India landmass is ambiguous.This,coupled with a limited understanding of the tectonic evolution of the mobile ...In paleogeographic reconstructions of the Columbia and Rodinia Supercontinents,the position of the Greater India landmass is ambiguous.This,coupled with a limited understanding of the tectonic evolution of the mobile belts along which the mosaic of crustal domains in India accreted,impedes precise correlation among the dispersed crustal fragments in supercontinent reconstructions.Using structural,metamorphic phase equilibria,chronological and geochemical investigations,this study aims to reconstruct the tectonic evolution of the Chottanagpur Gneiss Complex(CGC)as a distinct crustal block at the eastern end of the Greater Indian Proterozoic Fold Belt(GIPFOB)along which the North India Block(NIB)and the South India Block(SIB)accreted.The study focuses on two issues,e.g.dating the Early Neoproterozoic(0.92 Ga)accretion of the CGC with the NIB contemporaneous with the assembly of Rodinia,and documenting the widespread(>24,000 km^(2))plutonism of1.5-1.4 Ga weakly peraluminous,calc-alkalic to alkali-calcic and ferroan A-type granitoids(±garnet)devoid of mafic microgrannular enclaves and coeval mafic emplacements in the crustal block.These dominantly within-plate granitoids arguably formed by asthenospheric upwelling induced partial melting of garnetbearing anatectic quartzofeldspathic gneisses that dominate the Early Mesoproterozoic basement of the block.The major and trace element chemistry of the granitoids is similar to the 1.35-1.45 Ga A-type granitoids in Laurentia/Amazonia emplaced contemporaneous with the 1.5-1.3 Ga breakup of the Columbia Supercontinent.This study suggests the Chottanagpur Gneiss Complex occured as a fragmented crustal block following the breakup of the Columbia Supercontinent;the crustal block was subsequently integrated within India during the Early Neoproterozoic oblique accretion between the NIB and SIB contemporaneous with the Rodinia Supercontinent assembly.展开更多
Mosquito-borne diseases such as malaria,filariasis,dengue,chikungunya,Japanese encephalitis,yellow fever and Zika contribute significantly to health problems of developing as well as developed nations.Vector control i...Mosquito-borne diseases such as malaria,filariasis,dengue,chikungunya,Japanese encephalitis,yellow fever and Zika contribute significantly to health problems of developing as well as developed nations.Vector control is central to control of vector borne diseases.In the last four-five decades,biological control methods have been inducted in the integrated vector management strategy,advocated nationally as well as globally by the World Health Organization.Currently,biological control of vectors is globally acknowledged as the best available strategy in the wake of growing concerns about vector resistance as well as adverse effects of insecticides on the environment and non-target fauna co-inhabiting the same ecological niches as vectors.In India and elsewhere,efforts are ongoing to screen newer isolates to bring forth new biolarvicidal products of public health importance.In this review,by carrying out extensive literature survey,we discuss advances thus far and the prospects of bacilli-based control of vectors and vector borne diseases.展开更多
We used pre-sowing treatments v/z., soaking seeds in concen- trated sulphudc acid （CSA）, gibberellic acid （GA）, combined treatment of CSA ＋ GA and mechanical scarification to overcome seed dormancy and enhance sy...We used pre-sowing treatments v/z., soaking seeds in concen- trated sulphudc acid （CSA）, gibberellic acid （GA）, combined treatment of CSA ＋ GA and mechanical scarification to overcome seed dormancy and enhance synchronous germination of Macaranga peltata seeds. We analysed percent seed germination data by logistic regression and con- finned that except in GA treatment, time and acid concentration together were crucial for enhancing germination. The combination treatment of CSA and GA resulted in higher percent germination （up to 74%） than either treatment used separately, but produced defective seedlings （26%）. Mechanical scarification of seed coat had the greatest impact in enhanc- ing germination （78%） and reducing imbibition time （6 days） against the control （0%）. Germination studies and SEM analysis confirmed that seed germination in M. peltata was inhibited by seed coat dormancy.展开更多
In recent years, seasonal blooms of the dinoflagellate Noctiluca miliaris have appeared in the open-waters of the northern Arabian Sea （NAS）. This study provides the first characterization of bacteria from a seasona...In recent years, seasonal blooms of the dinoflagellate Noctiluca miliaris have appeared in the open-waters of the northern Arabian Sea （NAS）. This study provides the first characterization of bacteria from a seasonal bloom of green Noctiluca ofNAS （20°N-17°N and 64°E-70°E）, during the spring-inter-monsoon cruise ofSagar Sampada 253, in March 2007. Bacterial growth as assessed by most-probable number （MPN） and plate counts, revealed ＇variable-physiotypes＇ over a wide range of salinities （0%-25% w/v NaC1）, pH levels （5-8.5）, and organic nutrient strengths, in comparison to non-bloom waters. MPN indices of bacteria in surface waters of bloom stations ＊DWK and ＊PRB, corresponded to （3.08-4.41）×103 cells/mL at 3.5% NaC1 （w/v）, and （2.82-9.49）× 102 cells/mL at 25% （w/v） NaC1 in tryptone-yeast extract broth （TYE）. Plate counts were （1.12-4） × 106 CFU/mL at 0% （w/v） NaC1, （1.28-3.9） × 106 CFU/mL at 3.5% （w/v） NaC1, and （0.4- 7）×104 CFU/mL at 25% NaC1 （w/v） on TYE. One-tenth-strength Zobell＇s gave （0.6-3.74）× 105 CFU/mL at pH 5 to （3.58-7.5）× 105 CFU/mL at pH 8.5. These bacteria were identified to the genera Bacillus, Cellulomonas, Staphylococcus, Planococcus, Dietzia, Diergibacillus, Micrococcus, Sporosarcinae, Leucobacter, and Halomonas. The identity of three strains （GUFBSS253N2, GUFBSS253N30, and GUFBSS253N84） was confirmed through 16S rDNA sequence homology as Bacillus cohnii, Bacillusflexus, and Bacillus cereus. The -2-3-fold higher plate counts of culturable bacteria from the open-waters of the NAS indicate that these bacteria could critically determine the biogeochemical dynamics of the bloom and its milieu. The role of these bacteria in sustaining/terminating the bloom is under evaluation.展开更多
This study presents a comprehensive account of the petrogenetic and geodynamic evolution of the Bellara Trap volcanic rocks from the Ingaldhal Formation, Chitradurga Group, western Dharwar Craton(WDC). Geochemical att...This study presents a comprehensive account of the petrogenetic and geodynamic evolution of the Bellara Trap volcanic rocks from the Ingaldhal Formation, Chitradurga Group, western Dharwar Craton(WDC). Geochemical attributes of these rocks are consistent with two groups with distinct evolutionary trends: one comprising tholeiitic, MORB(mid-ocean ridge basalt) type basalts(BTB) and the other corresponding to calc-alkaline andesites(BTA). Basalts are essentially composed of clinopyroxene and plagioclase whereas the andesites are porphyritic with phenocrysts of plagioclase, clinopyroxene and polycrystalline quartz embedded in a groundmass of K-feldspar, quartz and opaques. Primary igneous mineralogy is overprinted by greenschist facies metamorphism resulting in chlorite-actinolite-plagioclase assemblage. The BTB samples reflect nearly flat REE patterns with weak LREE enrichment in contrast to pronounced LREE enhancement over HREE discernible for BTA. Tectonically, the BTB samples correspond to an active mid-oceanic ridge-rift setting with a MORB composition, whereas a back-arc basin(BAB) regime is corroborated for the BTA samples fractionating from back-arc basin basalts. Geochemical imprints of subduction input are more pronounced in BTA compared to BTB as mirrored by their elevated abundances of incompatible fluid mobile elements like Ba, Th, U and LREE. The BTB is endowed with an N-to E-MORB signature attributable to minor contributions from subduction-related components at the inception of a back-arc basin in the vicinity of an active subduction system. The BTA derived through differentiation of a basaltic magma with BABB(back-arc basin basalt) affinity compositionally akin to a heterogeneous source mantle carrying depleted MORB-type and enriched arc-type components inducted with progressive subduction. The BABB-type andesites and MORB-type basalts from Bellara Traps record a compositional heterogeneity of mantle in an intraoceanic arc-back arc system. Mantle processes invoke a BABB-MORB spectrum with a MORB-like endmember and an arc-like endmember associated with a juvenile back-arc basin. This study infers a Neoarchean analogue of Mariana-type back-arc rift setting proximal to the arc with a gradual transition from anhydrous to hydrous melting processes synchronized with MORB-mantle and arc-mantle interaction during initiation of a nascent back arc adjacent to the arc. The MORB-BABB compositional spectrum for the Bellara Traps conforms to a Neoarchean back-arc basin that evolved under an extensional tectonic regime associated with incipient stages of back-arc rifting and incorporation of subduction-derived components in the mantle output. This study complies with Neoarchean intraoceanic accretionary cycle plate tectonics in WDC.展开更多
High resolution shallow seismic data was acquired from inner continental shelf of Goa,west coast of India to map underlying stratigraphic and buried geomorphic features of shelf strata.Seismic data revealed characteri...High resolution shallow seismic data was acquired from inner continental shelf of Goa,west coast of India to map underlying stratigraphic and buried geomorphic features of shelf strata.Seismic data revealed characteristic channel incisions beneath 4-15 m thick sediment layer and corresponds to multi cycle incisions.Stratigraphic analysis of these incision signatures reveals three prominent subaerial unconformities S6,S7 and S9.These unconformities were exposed during the last glacial,penultimate glacial(MIS-6)and prior to penultimate glacial(MIS-8)periods.On the basis of interpreted age of subaerial unconformities and differences in their morphological features,observed channel incisions have been divided grossly into three phases of incision.Phase-1 incisions are older than^330 kyr BP,whereas,incisions of Phase-2 and Phase-3 correspond to^320-125 kyr BP and^115-10 kyr BP respectively.Plan form of these incisions varied from a straight channel type to ingrown meander and then to anastomosing channel types.These channels meet at the confluence of present-day Mandovi and Zuari rivers.The confluence point has varied in due course of time because of cyclic incision and burial with repeated sea level fluctuations.The preserved main channel width varies from^100 m to 1000 m.and maximum channel depth reaches up to^35 m.Comparison of quantitative and qualitative morphologic results of different phases of incisions suggest that Phase-2 channels had^33%more mean bank full discharge than that of the Phase-3 channels.Phase-2 incisions had been carved in higher hydraulic energy condition as compared to Phase-3 incisions implying that the Indian summer monsoon was better during formative stages of Phase-2 incisions.展开更多
We present data pertaining to mineral assemblages and composition of the Central Indian Ocean Basin(CIOB)pumices.Eight groups of pumices were identified considering the presence of phenocrysts of plagioclase,clinopyro...We present data pertaining to mineral assemblages and composition of the Central Indian Ocean Basin(CIOB)pumices.Eight groups of pumices were identified considering the presence of phenocrysts of plagioclase,clinopyroxene,orthopyroxene,hornblende and biotite together with the occurrence of quartz and glass.Pigeonite,fayalite and ulvospinelare reported for the first time from these pumices.In the eight groups,the modal percentage of the constituents are phenocrysts 3%to 19%(avg 9.6%),silicic glass 33%to 54%(avg 43%)and the rest is vesicles.Based on the above factors we have identified the possible sources of the CIOB pumices.The mineral compositions of plagioclase,pyroxenes,and biotite of the CIOB pumices were compared with those of Krakatau and Toba.Most of the plagioclase and pyroxene compositions resemble the Haranggoal Dacite Tuff of Toba and Krakatau.Considering the mineral assemblages and compositions,there are pumices which do not correlate to any of the above eruptions and are probably from yet unidentified source/sources.These sources could either be from nearby terrestrial volcanoes or intraplate seamounts present in the CIOB.In a global context,it is viable that petrological characteristics could be used as initial criteria to determine the source of pumices that occur at abyssal depths in the world ocean.展开更多
Considering the economic importance in traditional Chinese medicine(TCM) and lack of baseline information, we evaluated the proximate composition, fatty acid and amino acid profiles, trace element content and C:N rati...Considering the economic importance in traditional Chinese medicine(TCM) and lack of baseline information, we evaluated the proximate composition, fatty acid and amino acid profiles, trace element content and C:N ratio in the alligator pipefish, Syngnathoides biaculeatus. Amongst proximate principals, a crude protein formed the major biochemical component((58.9±2.2)% dry weight). Mean percent concentrations(dry weight) of other components such as a total lipid(TL), ash and nitrogen-free extract measured were,(1.8±0.2)%,(19.2±2.2)% and(20.1±0.45)%, respectively. The fatty acid profile revealed the presence of 27 saturated fatty acids(SFA) with 13 straight-chained and 14 branched-chained, 28 unsaturated fatty acids(UFA) with 14 monounsaturated and 14 polyunsaturated and nine other minor fatty acids. Mean percent contributions of total SFAs and UFAs to TL were found to be(55.41±0.24)% and(44.05±0.25)%, respectively. Altogether, 16 dif ferent amino acids with an equal number of essential(EAA) and non-essential(NAA) ones were identified. Percent contributions by EAA and NAA to the total amino acid content were 38.11% and 61.89%, respectively. Trace metal concentrations in S. biaculeatus were generally low and their distribution followed the order, Mg>Fe>Zn>Mn>Cu>Cr>Ni>Hg>Co. The C:N ratio was(4.37±0.04)%. The profile of major biochemical constituents in alligator pipefish, S. biaculeatus revealed its potential use in TCM as well as a nutritional diet for human consumption. The results of the study would also form the basis for formulation and optimization of diets for the culture of S. biaculeatus.展开更多
基金supported by the research award project RI/0220-10000618-001 to Sheth from the Industrial Research and Consultancy Centre(IRCC)IIT Bombay.Shekhar and Astha were supported by Prime Minister’s Research Fellowships(PMRF,File Nos.1303100 and 1303103,respectively)+4 种基金Naik was initially supported by an IIT Bombay Institute Post-Doctoral Fellowship(File No.HR-1(HRM-1)/Rect/33/2022/20003002)subsequently by a Goa State Research Foundation Post-doctoral Fellowship(File No.PDF2024003)We express our sincere gratitude to Prof.N.Prabhakar for kindly granting us access to the WD-XRF spectrometry facility(SIP ProjectWBS Code:IN/22-1111039E-01)the ICP-MS facility,and the SERB-funded EPMA National Facility(IRPHA Grant No.IR/S4/ESF-16/2009(G))in the Department of Earth Sciences,IIT Bombay.
文摘Large-scale Danian-age(post-K/Pg boundary)Deccan magmatism is well known from the Mumbai metropolitan area,located in the structurally complex Panvel flexure zone along the western Indian rifted continental margin.This compositionally diverse late-Deccan magmatic suite contains subaerial tholeiitic lavas and dykes typical of the main Deccan province,with many features atypical of the Deccan,such as spilitic pillow lavas,“intertrappean”sediments(often containing considerable volcanic ash),rhyolitic lavas and tuffs,gabbro-granophyre intrusions,and trachyte intrusions containing alkali basalt enclaves.Most of these units,previously dated at 62.5 Ma to 61 Ma,are contemporaneous with or slightly postdate the 62.5 Ma India-Seychelles continental breakup and Panvel flexure formation.In the Dongri-Uttan area,two samples of a>50-m-thick,columnar-jointed rhyolite from the Darkhan Quarry and from a section behind the current Uttan Sagari Police Station have previously been dated at 62.6±0.6 Ma and 62.9±0.2 Ma(^(40)Ar/^(39)Ar,2r errors).New exposures reveal that these two statistically indistinguishable 40 Ar/39 Ar ages correspond to two distinct rhyolite units,separated by well-bedded silicic ash.The columnar rhyolites are microcrystalline,composed of quartz and alkali feldspar,with rare small(1–2 mm),altered feldspar phenocrysts,and no recognisable relict vitroclasts.Given the westerly structural dip,most of their lateral extent is submerged under the Arabian Sea,and we consider them to be possible flood rhyolite lavas.We interpret the ash beds,composed of pumice clasts and glass shards,as a low-grade(nonwelded)vitric ash,derived from a possibly distal Plinian eruption and deposited by fallout.The lavas and ash are peraluminous rhyolites.The lavas are Sr-Ba-poor and Rb-Zr-Nb-rich,and show“seagull-shaped”rare earth element patterns with deep negative europium anomalies.These crystal-poor lavas are“hot-dry-reduced”rhyolites typical of intraplate,continental rift and rifted margin settings.The very different high-field strength element contents of the lavas and the ash indicate compositionally distinct magma batches.The 62.5 Ma Dongri-Uttan sequence provides clear evidence for rapid silicic eruptions of effusive and explosive nature,alternating with each other and sourced from distinct magma chambers and eruptive vents.A newly identified,highly feldspar-phyric trachyte intrusion marks the last phase of magmatic activity in the area,corresponding with late-stage trachyte-syenite intrusions exposed in coastal western India and the Seychelles,and shows that the Mumbai rhyolites and trachytes form a compositional continuum.
文摘Cold seeps are oases for biological communities on the sea floor around hydrocarbon emission pathways.Microbial utilization of methane and other hydrocarbons yield products that fuel rich chemosynthetic communities at these sites.One such site in the cold seep ecosystem of Krishna-Godavari basin(K-G basin)along the east coast of India,discovered in Feb 2018 at a depth of 1800 m was assessed for its bacterial diversity.The seep bacterial communities were dominated by phylum Proteobacteria(57%),Firmicutes(16%)and unclassified species belonging to the family Helicobacteriaceae.The surface sediments of the seep had maximum OTUs(operational taxonomic units)(2.27×10^(3))with a Shannon alpha diversity index of 8.06.In general,environmental parameters like total organic carbon(p<0.01),sulfate(p<0.001),sulfide(p<0.05)and methane(p<0.01)were responsible for shaping the bacterial community of the cold seep ecosystem in the K-G Basin.Environmental parameters play a significant role in changing the bacterial diversity richness between different cold seep environments in the oceans.
基金support provided by the Planning Commission,Government of India,New Delhi for carrying out this study
文摘Thirty-six medicinal plant species belonging to 25 families were surveyed to study Arbuscular mycorrhizal （AM） fungal diversity from different localities of North and South Goa of Western Ghats, Goa region, India. A total of 30 medicinal plant species were found to be mycorrhizal and six plant species showed absence of AM fungal colonization. Forty two AM fungal species belonging to five genera viz., Glomus, Acaulospora, Scutellospora, Gigaspora and Ambispora were recovered from the rhizosphere soil. Glomus was found to be the most dominant genera in the study sites, and Glomus fasciculatum the most dominant AM fungal species. Negative significant correlation was observed between percent colonization and spore density. Simpson＇s and Shannon Weiner diversity index studies carried out in North and South Goa exhibited less variation in both the sites, indicating a stable and a diverse plant community.
基金supported by Planning Commission,Government of India, New Delhi
文摘Seventeen mangrove species of eight families at seven river- ine and fringe habitats in Goa West India were surveyed for Arbuscular Mycorrhizal （AM） fungal diversity. Sixteen species were found to be mycorrhizal and one species showed no AM fungal colonization. AM root colonization was recorded at all seven sites and ranged from 6%-77%. Maximum root colonization was recorded in Excoecaria agal- locha （77%） and minimum colonization in Avicennia marina （6%）. Paris-type colonization was predominant at all sites. Auxiliary cells were recorded in roots of Acanthus ilicifolius, Ceriops tagal and Sonneretia alba. AM fungal root colonization and spore density varied by plant species and site. Site average spore density ranged from 1.84 spores.g^-1 to 0.54 spores.g-1 of soil. In total, 28 AM fungal species of five genera, viz. Glomus, Acaulospora, Scutellospora, Gigaspora and Entrophospora, were recovered. Glomus was the dominant genus, three species of which were sporocarpic forms. Maximum site species richness （SR） ranged from 16 to 5. Species richness was maximum in A. ilicifolius where seven species of three genera were recovered. Based on relative abun- dance （RA） and isolation frequency （IF）, two common species, viz. G. intraradices and A. laevis, were recovered from all seven sites.
文摘The Precambrian greywacke of Ribandar-Chimbel belonging to the Sanvordem Formation of the Goa Group, India, has been studied for petrography and analyzed for major trace elements. The greywacke is characterized by angular to sub-round grains of quartz, feldspar, biotite, chlorite and clay minerals. The abundance of clay in the matrix seems to have influenced the Al2O3 content and the K20/Al2O3 ratio. The variation diagrams indicate a decreasing trend of TiO2, Al2O3, Fe2O3 and MgO; whereas Na2O and CaO exhibit a scatter which could be a result of the variable presence of feldspar within the sediments. The immobile elements, vanadium （25 to 144 ppm）, nickel （up to 107 ppm） and chromium （up to 184 ppm）, reflect abundance of clay minerals. The greywacke shows strongly fractionated REE patterns with LaN/YbN = 8 to 26 and with higher total REE abundances （up to 245 ppm）. The low REE enrichment and depletion in heavier REE with prominent negative Eu anomaly （Eu/Eu^＊= 0.54 to 0.79） suggest a derivation of the greywacke from an old upper continental crust composed chiefly of felsic components. Petrological evidence and geochemical data suggest that the deposition of the greywacke largely took place in a deep to shallow basin that progressively chang- ed from that of a continental island arc to an active continental setting.
文摘Emotion recognition is a growing field that has numerous applications in smart healthcare systems and Human-Computer Interaction(HCI).However,physical methods of emotion recognition such as facial expressions,voice,and text data,do not always indicate true emotions,as users can falsify them.Among the physiological methods of emotion detection,Electrocardiogram(ECG)is a reliable and efficient way of detecting emotions.ECG-enabled smart bands have proven effective in collecting emotional data in uncontrolled environments.Researchers use deep machine learning techniques for emotion recognition using ECG signals,but there is a need to develop efficient models by tuning the hyperparameters.Furthermore,most researchers focus on detecting emotions in individual settings,but there is a need to extend this research to group settings aswell since most of the emotions are experienced in groups.In this study,we have developed a novel lightweight one dimensional(1D)Convolutional Neural Network(CNN)model by reducing the number of convolution,max pooling,and classification layers.This optimization has led to more efficient emotion classification using ECG.We tested the proposed model’s performance using ECG data from the AMIGOS(A Dataset for Affect,Personality and Mood Research on Individuals andGroups)dataset for both individual and group settings.The results showed that themodel achieved an accuracy of 82.21%and 85.62%for valence and arousal classification,respectively,in individual settings.In group settings,the accuracy was even higher,at 99.56%and 99.68%for valence and arousal classification,respectively.By reducing the number of layers,the lightweight CNNmodel can process data more quickly and with less complexity in the hardware,making it suitable for the implementation on the mobile phone devices to detect emotions with improved accuracy and speed.
基金the funding received from the Science and Engineering Research Board (SERB), Govt. of India under GAP 3291funded by Ministry of Earth Science (MoES) with project reference number Mo ES/ P.O. (Seismic) 8 (09)-Geochron/2012。
文摘Hydrous Cr-bearing uvarovite garnets are rare in natural occurrences and belong to the ugrandite series and exist in binary solid solutions with grossular and andradite garnets. Here, we report the occurrence of hydrous uvarovite garnet having Cr_(2)O_(3) upto 19.66 wt% and CaO of 32.12–35.14 wt% in the serpentinized mantle peridotites of Naga Hills Ophiolite(NHO), India. They occur in association with low-Cr diopsides. They are enriched in LILE(Ba, Sr), LREEs, with fractionating LREE-MREE [avg.(La/Sm)_(N) = 2.16] with flat MREE/HREE patterns [avg.(Sm/Yb)_(N) = 0.95]. Raman spectra indicate the presence of hydroxyl(OH^(–)) peaks from 3500 to 3700 cm^(-1). Relative abundances in fluid mobile elements and their close association with clinopyroxenes are suggestive of the formation of uvarovite garnets through low temperature metasomatic alteration of low-Cr diopsides by hydrothermal slab fluids. The high LREE concentration and absence of Eu anomaly in the garnet further attest to alkaline nature of the transporting slab dehydrated fluid rather the involvement of low-p H solution. The chemical characteristics of the hydroxyl bearing uvarovite hosted by the mantle peridotite of NHO deviate from the classical features of uvarovite garnet, and their origin is attributed to the fluid-induced metasomatism of the sub arc mantle wedge in a suprasubduction zone regime.
基金the funds from Council of Scientific and Industrial Research(CSIR)to National Geophysical Research Institute through the project of MLP 6604-28(CM)Ministry of Earth Sciences(No:MoES/PO(Geosci)/8/2014)
文摘This study reports major, trace, rare earth and platinum group element compositions of lava flows from the Vempalle Formation of Cuddapah Basin through an integrated petrological and geochemical approach to address mantle conditions, magma generation processes and tectonic regimes involved in their formation. Six flows have been identified on the basis of morphological features and systematic three-tier arrangement of vesicular-entablature-colonnade zones. Petrographically, the studied flows are porphyritic basalts with plagioclase and clinopyroxene representing dominant phenocrystal phases.Major and trace element characteristics reflect moderate magmatic differentiation and fractional crystallization of tholeiitic magmas. Chondrite-normalized REE patterns corroborate pronounced LREE/HREE fractionation with LREE enrichment over MREE and HREE. Primitive mantle normalized trace element abundances are marked by LILE-LREE enrichment with relative HFSE depletion collectively conforming to intraplate magmatism with contributions from sub-continental lithospheric mantle(SCLM) and extensive melt-crust interaction. PGE compositions of Vempalle lavas attest to early sulphur-saturated nature of magmas with pronounced sulphide fractionation, while PPGE enrichment over IPGE and higher Pd/Ir ratios accord to the role of a metasomatized lithospheric mantle in the genesis of the lava flows. HFSEREE-PGE systematics invoke heterogeneous mantle sources comprising depleted asthenospheric MORB type components combined with plume type melts. HFSE-REE variations account for polybaric melting at variable depths ranging from garnet to spinel lherzolite compositional domains of mantle. Intraplate tectonic setting for the Vempalle flows with P-MORB affinity is further substantiated by(i) their origin from a rising mantle plume trapping depleted asthenospheric MORB mantle during ascent,(ii) interaction between plume-derived melts and SCLM,(iii) their rift-controlled intrabasinal emplacement through Archeane Proterozoic cratonic blocks in a subduction-unrelated ocean-continent transition zone(OCTZ). The present study is significant in light of the evolution of Cuddapah basin in the global tectonic framework in terms of its association with Antarctica, plume incubation, lithospheric melting and thinning, asthenospheric infiltration collectively affecting the rifted margin of eastern Dharwar Craton and serving as precursors to supercontinent disintegration.
基金supported by UGC,New Delhi,under UGC-SAP program
文摘AMnO3 （A=Sr, Sm and Nd） manganites with perovskite structure, prepared by combustion method were characterized by X-ray diffraction （XRD）, infra-red spectroscopy, Brunauer-Emmett-Teller （BET） surface area analyzer and scanning electron microscopy （SEM）. The solid state and spectroscopic studies such as electrical resistivity, magnetic susceptibility, electron spin resonance （ESR） and diffuse reflectance spectroscopy were carried out and attempted to correlate with the catalytic activities of the compounds. To evaluate the catalytic activity, a model reaction of CO oxidation over these compounds was undertaken. An attempt was made to understand the effect of A-site change by different metal cations in the manganite perovskites on solid state and catalytic properties.
基金the funds from Council of Scientific and Industrial Research(CSIR)to CSIR-National Institute of Oceanography through the MLP-1703 and GAP 2175 projectsupported by Foreign Expert funding from CUGB and Professorial position at the Adelaide University
文摘The ophiolite suite from south Andaman Islands forms part of the Tethyan Ophiolite Belt and preserves the remnants of an ideal ophiolite sequence comprising a basal serpentinized and tectonised mantle peridotite followed by ultramafic and mafic cumulate units, basaltic dykes and spilitic pillow basalts interlayered with arkosic wacke. Here, we present new major, trace, rare earth(REE) and platinum group(PGE) element data for serpentinized and metasomatized peridotites(dunites) exposed in south Andaman representing the tectonized mantle section of the ophiolite suite. Geochemical features of the studied rocks, marked by Al_2 O_3/TiO_2 > 23, LILE-LREE enrichment, HFSE depletion, and U-shaped chondrite-normalized REE patterns with(La/Sm)N > 1 and(Gd/Yb)N <1, suggest contributions from boninitic mantle melts. These observations substantiate a subduction initiation process ensued by rapid slab roll-back with extension and seafloor spreading in an intraoceanic fore-arc regime. The boninitic composition of the serpentinized peridotites corroborate fluid and melt interaction with mantle manifested in terms of(i) hydration, metasomatism and serpentinization of depleted, MORB-type, sub-arc wedge mantle residual after repeated melt extraction; and(ii) refertilization of refractory mantle peridotite by boninitic melts derived at the initial stage of intraoceanic subduction. Serpentinized and metasomatized mantle dunites in this study record both MOR and intraoceanic arc signatures collectively suggesting suprasubduction zone affinity. The elevated abundances of Pd(4.4-12.2 ppb) with highΣPPGE/∑IPGE(2-3) and Pd/Ir(2-5.5) ratios are in accordance with extensive melt-rock interaction through percolation of boninitic melts enriched in fluid-fluxed LILE-LREE into the depleted mantle after multiple episodes of melt extraction. The high Pd contents with relatively lower Ir concentrations of the samples are analogous to characteristic PGE signatures of boninitic magmas and might have resulted by the infiltration of boninitic melts into the depleted and residual mantle wedge peridotite during fore-arc extension at the initial stage of intraoceanic subduction. The PGE patterns with high Os + Ir(2-8.6 ppb)and Ru(2.8-8.4 ppb) also suggest mantle rejuvenation by infiltration of melts derived by high degree of mantle melting. The trace, REE and PGE data presented in our study collectively reflect heterogeneous mantle compositions and provide insights into ocean-crust-mantle interaction and associated geochemical cycling within a suprasubduction zone regime.
基金the funds from Department of Science and Technology,Govt.of India under ECR/2018/000309 project。
文摘The Naga Hills Ophiolite(NHO)belt in the Indo-Myanmar range(IMR)represents a segment of Tethyan oceanic crust and upper mantle that was involved in an eastward convergence and collision of the Indian Plate with the Burmese Plate during the Late Cretaceous-Eocene.Here,we present a detailed petrological and geochemical account for the mantle and crustal sections of NHO,northeastern India to address(i)the mantle processes and tectonic regimes involved in their genesis and(ii)their coherence in terms of the thermo-tectonic evolution of Tethyan oceanic crust and upper mantle.The NHO suite comprises well preserved crustal and mantle sections discretely exposed at Moki,Ziphu,Molen,Washelo and Lacham areas.The ultramafic-mafic lithologies of NHO are mineralogically composed of variable proportions of olivine,orthopyroxene,clinopyroxene and plagioclase.The primary igneous textures for the mantle peridotites have been overprinted by extensive serpentinisation whereas the crustal section rocks reflect crystal cumulation in a magma chamber.Chondrite normalised REE profiles for the cumulate peridotite-olivine gabbro-gabbro assemblage constituting the crustal section of NHO show flat to depleted LREE patterns consistent with their generation from depleted MORB-type precursor melt in an extensional tectonic setting,while the mantle peridotites depict U-shaped REE patterns marked by relative enrichment of LREE and HREE over MREE.These features collectively imply a dual role of depleted MORB-type and enriched arc-type mantle components for their genesis with imprints of melt-rock and fluid-rock interactions.Tectonically,studied lithologies from NHO correspond to a boninitic to slab-proximal Island Arc Tholeiite affinity thereby conforming to an intraoceanic supra subduction zone(SSZ)fore-arc regime coherent with the subduction initiation process.The geochemical attributes for the crustal and mantle sections of NHO as mirrored by Zr/Hf,Zr/Sm,Nb/Ta,Zr/Nb,Nb/U,Ba/Nb,Ba/Th,Ba/La and Nd/Hf ratios propound a two-stage petrogenetic process:(i)a depleted fore arc basalt(FAB)type tholeiitic melt parental to the crustal lithologies was extracted from the upwelling asthenospheric mantle at SSZ fore-arc extensional regime thereby rendering a refractory residual upper mantle;(ii)the crust and upper mantle of the SSZ fore arc were progressively refertilised by boninitic melts generated in response to subduction initiation and slab-dehydration.The vestiges of Tethyan oceanic lithosphere preserved in NHO represent an accreted intra-oceanic fore arc crust and upper mantle section which records a transitional geodynamic evolution in a SSZ regime marked by subduction initiation,fore arc extension and arc-continent accretion.
基金the support of CSIR Senior Research Fellowship,Indiaa part of the“Polymetallic Nodule:Survey and Exploration”project(GAP 2175)supported by Ministry of Earth Sciences,Govt.of India.This is NIO's contribution No.6633。
文摘This study presents new major,trace and REE data for thirty-five ferromanganese nodules recovered from areas representing three different sediment types(siliceous,red clay and their transition zone)in the Central Indian Ocean Basin(CIOB)to address their genetic aspects,classification,growth rate,nature of host sediments and influence of REE in the processes of nodule formation.The nodules from CIOB are mostly either hydrogenetic(metals coming from oxygenated bottom water)and diagenetic(metals coming from suboxic sediment pore water)or a combination of both,depending on the source of supply of metal.However,a number of biogeochemical processes mediate this supply of metals which again changes from time to time,making the nodule growth process highly dynamic.This study suggests that at the initial stage of nodule growth,host sediments do not play much role in controlling the growth processes for which REEs can enter both Mn and Fe oxyhydroxide phases equally.Thus,the bottom water signature is imprinted in these early formed nodules irrespective of their host sediment substrate but with gradual growth and burial in the sediment,the main mode of metal enrichment becomes diagenetic through sediment pore water.This tends to increase the concentration of Mn,Ni and Cu over other elements which are retained in the sediment fraction.Among the REEs,Ce concentration of the nodules shows significant positive anomaly due to variation in redox potential and hence its magnitude can be used to get an idea about the metal enrichment procedure and the genetic type of the nodules.However,based on host sediment only,not much difference is found in the magnitude of Ce anomaly in these nodules.On the other hand,discrimination diagram,based on HFSE and REY chemistry,indicates that most of these nodules are of diagenetic origin under oxic condition with a trend towards hydrogenetic field.Further,the genetic type of the ferromanganese nodules from the CIOB are more effectively differentiated by a combination of their major and trace element concentrations rather than solely based on their REE or HFSE chemistry or host sediment substrate.
基金the financial support provided by UGC(India)fellowshipthe financial support for fieldwork provided through the CPDA funding scheme by Indian Institute of Technology,Kharagpur+2 种基金Invaluable support by Atreyee Bhattacharya(INSTAAR,Boulder)via internal educational initiative grants at University of ColoradoBoulder for the SIMS geochronology work at UCLA is greatly appreciatedThe UCLA Ion Microprobe Laboratory is partially supported by a grant from NSF-EAR’s Instrumentation and Facilities Program(1734856)。
文摘In paleogeographic reconstructions of the Columbia and Rodinia Supercontinents,the position of the Greater India landmass is ambiguous.This,coupled with a limited understanding of the tectonic evolution of the mobile belts along which the mosaic of crustal domains in India accreted,impedes precise correlation among the dispersed crustal fragments in supercontinent reconstructions.Using structural,metamorphic phase equilibria,chronological and geochemical investigations,this study aims to reconstruct the tectonic evolution of the Chottanagpur Gneiss Complex(CGC)as a distinct crustal block at the eastern end of the Greater Indian Proterozoic Fold Belt(GIPFOB)along which the North India Block(NIB)and the South India Block(SIB)accreted.The study focuses on two issues,e.g.dating the Early Neoproterozoic(0.92 Ga)accretion of the CGC with the NIB contemporaneous with the assembly of Rodinia,and documenting the widespread(>24,000 km^(2))plutonism of1.5-1.4 Ga weakly peraluminous,calc-alkalic to alkali-calcic and ferroan A-type granitoids(±garnet)devoid of mafic microgrannular enclaves and coeval mafic emplacements in the crustal block.These dominantly within-plate granitoids arguably formed by asthenospheric upwelling induced partial melting of garnetbearing anatectic quartzofeldspathic gneisses that dominate the Early Mesoproterozoic basement of the block.The major and trace element chemistry of the granitoids is similar to the 1.35-1.45 Ga A-type granitoids in Laurentia/Amazonia emplaced contemporaneous with the 1.5-1.3 Ga breakup of the Columbia Supercontinent.This study suggests the Chottanagpur Gneiss Complex occured as a fragmented crustal block following the breakup of the Columbia Supercontinent;the crustal block was subsequently integrated within India during the Early Neoproterozoic oblique accretion between the NIB and SIB contemporaneous with the Rodinia Supercontinent assembly.
文摘Mosquito-borne diseases such as malaria,filariasis,dengue,chikungunya,Japanese encephalitis,yellow fever and Zika contribute significantly to health problems of developing as well as developed nations.Vector control is central to control of vector borne diseases.In the last four-five decades,biological control methods have been inducted in the integrated vector management strategy,advocated nationally as well as globally by the World Health Organization.Currently,biological control of vectors is globally acknowledged as the best available strategy in the wake of growing concerns about vector resistance as well as adverse effects of insecticides on the environment and non-target fauna co-inhabiting the same ecological niches as vectors.In India and elsewhere,efforts are ongoing to screen newer isolates to bring forth new biolarvicidal products of public health importance.In this review,by carrying out extensive literature survey,we discuss advances thus far and the prospects of bacilli-based control of vectors and vector borne diseases.
基金the Ministry of Minority Affairs-UGC,New Delhi,India for providing financial assistance(MANF)
文摘We used pre-sowing treatments v/z., soaking seeds in concen- trated sulphudc acid （CSA）, gibberellic acid （GA）, combined treatment of CSA ＋ GA and mechanical scarification to overcome seed dormancy and enhance synchronous germination of Macaranga peltata seeds. We analysed percent seed germination data by logistic regression and con- finned that except in GA treatment, time and acid concentration together were crucial for enhancing germination. The combination treatment of CSA and GA resulted in higher percent germination （up to 74%） than either treatment used separately, but produced defective seedlings （26%）. Mechanical scarification of seed coat had the greatest impact in enhanc- ing germination （78%） and reducing imbibition time （6 days） against the control （0%）. Germination studies and SEM analysis confirmed that seed germination in M. peltata was inhibited by seed coat dormancy.
文摘In recent years, seasonal blooms of the dinoflagellate Noctiluca miliaris have appeared in the open-waters of the northern Arabian Sea （NAS）. This study provides the first characterization of bacteria from a seasonal bloom of green Noctiluca ofNAS （20°N-17°N and 64°E-70°E）, during the spring-inter-monsoon cruise ofSagar Sampada 253, in March 2007. Bacterial growth as assessed by most-probable number （MPN） and plate counts, revealed ＇variable-physiotypes＇ over a wide range of salinities （0%-25% w/v NaC1）, pH levels （5-8.5）, and organic nutrient strengths, in comparison to non-bloom waters. MPN indices of bacteria in surface waters of bloom stations ＊DWK and ＊PRB, corresponded to （3.08-4.41）×103 cells/mL at 3.5% NaC1 （w/v）, and （2.82-9.49）× 102 cells/mL at 25% （w/v） NaC1 in tryptone-yeast extract broth （TYE）. Plate counts were （1.12-4） × 106 CFU/mL at 0% （w/v） NaC1, （1.28-3.9） × 106 CFU/mL at 3.5% （w/v） NaC1, and （0.4- 7）×104 CFU/mL at 25% NaC1 （w/v） on TYE. One-tenth-strength Zobell＇s gave （0.6-3.74）× 105 CFU/mL at pH 5 to （3.58-7.5）× 105 CFU/mL at pH 8.5. These bacteria were identified to the genera Bacillus, Cellulomonas, Staphylococcus, Planococcus, Dietzia, Diergibacillus, Micrococcus, Sporosarcinae, Leucobacter, and Halomonas. The identity of three strains （GUFBSS253N2, GUFBSS253N30, and GUFBSS253N84） was confirmed through 16S rDNA sequence homology as Bacillus cohnii, Bacillusflexus, and Bacillus cereus. The -2-3-fold higher plate counts of culturable bacteria from the open-waters of the NAS indicate that these bacteria could critically determine the biogeochemical dynamics of the bloom and its milieu. The role of these bacteria in sustaining/terminating the bloom is under evaluation.
基金supported by the projects of the CSIR-Emeritus ScientistINDEX Project from the Council of Scientific and Industrial Research (CSIR) to the National Geophysical Research Institute to Chakravadhanula Manikyamba+1 种基金the SERB-Research Scientist Project (No. SB/SRS/2019-20/27/EA) to Sohini Gangulythe DST INSPIRE fellowship for pursuing the Ph.D. programm at NGRI to Arijit Pahari。
文摘This study presents a comprehensive account of the petrogenetic and geodynamic evolution of the Bellara Trap volcanic rocks from the Ingaldhal Formation, Chitradurga Group, western Dharwar Craton(WDC). Geochemical attributes of these rocks are consistent with two groups with distinct evolutionary trends: one comprising tholeiitic, MORB(mid-ocean ridge basalt) type basalts(BTB) and the other corresponding to calc-alkaline andesites(BTA). Basalts are essentially composed of clinopyroxene and plagioclase whereas the andesites are porphyritic with phenocrysts of plagioclase, clinopyroxene and polycrystalline quartz embedded in a groundmass of K-feldspar, quartz and opaques. Primary igneous mineralogy is overprinted by greenschist facies metamorphism resulting in chlorite-actinolite-plagioclase assemblage. The BTB samples reflect nearly flat REE patterns with weak LREE enrichment in contrast to pronounced LREE enhancement over HREE discernible for BTA. Tectonically, the BTB samples correspond to an active mid-oceanic ridge-rift setting with a MORB composition, whereas a back-arc basin(BAB) regime is corroborated for the BTA samples fractionating from back-arc basin basalts. Geochemical imprints of subduction input are more pronounced in BTA compared to BTB as mirrored by their elevated abundances of incompatible fluid mobile elements like Ba, Th, U and LREE. The BTB is endowed with an N-to E-MORB signature attributable to minor contributions from subduction-related components at the inception of a back-arc basin in the vicinity of an active subduction system. The BTA derived through differentiation of a basaltic magma with BABB(back-arc basin basalt) affinity compositionally akin to a heterogeneous source mantle carrying depleted MORB-type and enriched arc-type components inducted with progressive subduction. The BABB-type andesites and MORB-type basalts from Bellara Traps record a compositional heterogeneity of mantle in an intraoceanic arc-back arc system. Mantle processes invoke a BABB-MORB spectrum with a MORB-like endmember and an arc-like endmember associated with a juvenile back-arc basin. This study infers a Neoarchean analogue of Mariana-type back-arc rift setting proximal to the arc with a gradual transition from anhydrous to hydrous melting processes synchronized with MORB-mantle and arc-mantle interaction during initiation of a nascent back arc adjacent to the arc. The MORB-BABB compositional spectrum for the Bellara Traps conforms to a Neoarchean back-arc basin that evolved under an extensional tectonic regime associated with incipient stages of back-arc rifting and incorporation of subduction-derived components in the mantle output. This study complies with Neoarchean intraoceanic accretionary cycle plate tectonics in WDC.
基金financial support as JRF&SRF(Fellowship letter No.23/12/2012(ii)EU-V)
文摘High resolution shallow seismic data was acquired from inner continental shelf of Goa,west coast of India to map underlying stratigraphic and buried geomorphic features of shelf strata.Seismic data revealed characteristic channel incisions beneath 4-15 m thick sediment layer and corresponds to multi cycle incisions.Stratigraphic analysis of these incision signatures reveals three prominent subaerial unconformities S6,S7 and S9.These unconformities were exposed during the last glacial,penultimate glacial(MIS-6)and prior to penultimate glacial(MIS-8)periods.On the basis of interpreted age of subaerial unconformities and differences in their morphological features,observed channel incisions have been divided grossly into three phases of incision.Phase-1 incisions are older than^330 kyr BP,whereas,incisions of Phase-2 and Phase-3 correspond to^320-125 kyr BP and^115-10 kyr BP respectively.Plan form of these incisions varied from a straight channel type to ingrown meander and then to anastomosing channel types.These channels meet at the confluence of present-day Mandovi and Zuari rivers.The confluence point has varied in due course of time because of cyclic incision and burial with repeated sea level fluctuations.The preserved main channel width varies from^100 m to 1000 m.and maximum channel depth reaches up to^35 m.Comparison of quantitative and qualitative morphologic results of different phases of incisions suggest that Phase-2 channels had^33%more mean bank full discharge than that of the Phase-3 channels.Phase-2 incisions had been carved in higher hydraulic energy condition as compared to Phase-3 incisions implying that the Indian summer monsoon was better during formative stages of Phase-2 incisions.
基金Part of the research was supported under Endeavour Fellowship awarded to Niyati G.Kalangutkar by Government of Australia and the work was conducted at Queensland University of Technology Laboratory, Brisbane, Queensland
文摘We present data pertaining to mineral assemblages and composition of the Central Indian Ocean Basin(CIOB)pumices.Eight groups of pumices were identified considering the presence of phenocrysts of plagioclase,clinopyroxene,orthopyroxene,hornblende and biotite together with the occurrence of quartz and glass.Pigeonite,fayalite and ulvospinelare reported for the first time from these pumices.In the eight groups,the modal percentage of the constituents are phenocrysts 3%to 19%(avg 9.6%),silicic glass 33%to 54%(avg 43%)and the rest is vesicles.Based on the above factors we have identified the possible sources of the CIOB pumices.The mineral compositions of plagioclase,pyroxenes,and biotite of the CIOB pumices were compared with those of Krakatau and Toba.Most of the plagioclase and pyroxene compositions resemble the Haranggoal Dacite Tuff of Toba and Krakatau.Considering the mineral assemblages and compositions,there are pumices which do not correlate to any of the above eruptions and are probably from yet unidentified source/sources.These sources could either be from nearby terrestrial volcanoes or intraplate seamounts present in the CIOB.In a global context,it is viable that petrological characteristics could be used as initial criteria to determine the source of pumices that occur at abyssal depths in the world ocean.
文摘Considering the economic importance in traditional Chinese medicine(TCM) and lack of baseline information, we evaluated the proximate composition, fatty acid and amino acid profiles, trace element content and C:N ratio in the alligator pipefish, Syngnathoides biaculeatus. Amongst proximate principals, a crude protein formed the major biochemical component((58.9±2.2)% dry weight). Mean percent concentrations(dry weight) of other components such as a total lipid(TL), ash and nitrogen-free extract measured were,(1.8±0.2)%,(19.2±2.2)% and(20.1±0.45)%, respectively. The fatty acid profile revealed the presence of 27 saturated fatty acids(SFA) with 13 straight-chained and 14 branched-chained, 28 unsaturated fatty acids(UFA) with 14 monounsaturated and 14 polyunsaturated and nine other minor fatty acids. Mean percent contributions of total SFAs and UFAs to TL were found to be(55.41±0.24)% and(44.05±0.25)%, respectively. Altogether, 16 dif ferent amino acids with an equal number of essential(EAA) and non-essential(NAA) ones were identified. Percent contributions by EAA and NAA to the total amino acid content were 38.11% and 61.89%, respectively. Trace metal concentrations in S. biaculeatus were generally low and their distribution followed the order, Mg>Fe>Zn>Mn>Cu>Cr>Ni>Hg>Co. The C:N ratio was(4.37±0.04)%. The profile of major biochemical constituents in alligator pipefish, S. biaculeatus revealed its potential use in TCM as well as a nutritional diet for human consumption. The results of the study would also form the basis for formulation and optimization of diets for the culture of S. biaculeatus.
