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Petrogenesis of massif-type anorthosite complex, Gruber, Central Dronning Maud Land, East Antarctica: Implications for magma source and evolution

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Chinese Journal Of Geochemistry 2009年第4期28卷 340-350页

作者： Anju Pandey Amit Dharwadkar rasik ravindra Andy Milton National Oceanography Centre European WaySouthampton SO14 3ZH United Kingdom Geological Survey of India FaridabadNH31 Haryana India National Centre for Antarctic & Ocean Research Goa-403804 India

The origin of anorthosite and associated igneous gabbronorite and ferrodiorite was investigated through detailed study of a typical massif-type anorthosite complex from Gruber, Central Dronning Maud Land, East Antarc- tica. Field observations showed that the Gruber Complex is made up of gabbronorite-anorthosite pluton which was intruded by ferrodiorite dykes. Systematic samples collected from the Gruber Complex revealed significant geo- chemical variations within the region. Four rock types have been identified, based on modal proportions of mineral phases and their geochemistry data. Clinopyroxene-gabbronorite and plagioclase-gabbronorite are the two types of gabbronorite with the dominance of clinopyroxene and plagioclase, respectively. Anorthosite is represented by rocks having predominance of plagioclase with minor clinopyroxene. Ferrodiorite is characterized by modal abundance of orthopyroxene and Fe-Ti oxide. Major and trace element systematics showed that all the four rock types are co-magmatic and are related through fractional crystallization. Based on this study, it is reported that clinopyroxene was the first phase to crystallize followed by plagioclase and then Fe-Ti oxides. Furthermore, trace element composition of the parental melt was calculated using LA-ICPMS analysis of the most primitive, pure clinopyroxene found in the clinopyroxene gabbronorite. Our analyses suggested that the parental melt was similar to that of continental arc basalt and showed signatures of subduction-related metasomatism. Based on mineral chemical and geochemical data, it is interpreted that the parent melt went through changing sequence of crystallization which led to the forma- tion of massive anorthosite.

关键词：东南极洲斜长岩岩浆源块型成因中央演变

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Elemental variations in glacier cryoconites of Indian Himalaya and Spitsbergen,Arctic

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Geoscience Frontiers 2017年第6期8卷 1339-1347页

作者： Shiv Mohan Singh Kumar Avinash Parmanand Sharma ravindra Uttam Mulik Ajay Kumar Upadhyay rasik ravindra Earth System Science Organisation National Centre for Antarctic and Ocean ResearchHeadland SadaGoa403804India National Research Centre for Grapes Pune412307India Ministry of Earth Sciences Prithvi BhavanIMD CampusOpp.India Habitat CentreLodi RoadNew Delhi110003India

Cryoconite samples were collected from two different climatic domains i.e.,the Sutri Dhaka glacier,western Himalaya India and Svalbard glaciers,the Spitsbergen,Arctic,to understand the elemental source and elemental deposition *** data of geochemical analysis suggest that the Himalayan cryoconite samples accumulate higher concentrations as compared to the cryoconite samples of the Arctic *** concentration of lithophile elements(Cs,Li,Rb and U)was recorded higher in the cryoconite holes of the Himalayas,especially,in the lower to the higher parts of the glacier,whereas,lower concentrations were recorded in the Arctic *** elements in the Himalayan cryoconites are enriched in As and Bi while the Arctic cryoconite samples show a higher concentration of Bi,Pb and *** higher concentrations are responsible for influencing the ecosystem and in human health related *** elements(Co,Fe,Mn and Ni)show high concentrations in the Himalayan samples,whereas,the Arctic samples show minor variations and low elemental concentration in these elements,*** addition,a few elements,such as Ag,Mg,and Ca show higher concentration in the Himalayan glacier *** also occurs in high concentrations in Arctic glacier samples.R-mode factor analysis of the Himalayas(Arctic)samples indicate that the elements are distributed in four(three)factors,explaining 89%(90%)of the variance in their elemental *** Factor 1 suggests statistically significant positive loadings for most of the lithophile,chalcophile and siderophile elements of the "Himalayan" and the Arctic cryoconite *** sample-wise factor score distribution shows a considerable variation in the sampling locations along the glaciers of both the *** 2 and 3,demonstrate insignificant loading for most of the elements,except statistically significant positive loading in some of the elements of the both,Himalayan and Arctic "cryoconites".The higher el

关键词： Cryoconite Elemental concentration Factor analyses Himalaya Spitsbergen

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Variability of Nonionellina labradorica Dawson in Surface Sediments from Kongsfjorden,West Spitsbergen

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Acta Geologica Sinica(English Edition) 2011年第3期85卷 549-558页

作者： Suhas SHETYE Rahul MOHAN Sunil Kumar SHUKLA Sudhakar MARUTHADU rasik ravindra National Centre for Antarctic and Ocean Research Goa India Ministry of Earth Sciences New Delhi India

Kongsfjorden is a fjord in Spitsbergen（Svalbard archipelago）that lies adjacent to both Arctic and Atlantic water masses and is therefore a suitable site to understand the effects of climate change on *** decipher the effect of the lateral advection of transformed Atlantic water （TAW）within the fjord,spatial variations of foraminiferal tests,their test size variations and stable isotopic composition（δ^（13）C andδ^（18）O）in the surface sediments were *** organic carbon and textural analyses were also carried *** dominant benthic foraminifera included Nonionellina labradorica,Elphidium excavatum,Cassidulina reniforme,Quinqueloculina stalkeri and Islandiella *** labradorica was the predominant species in the outer fjord,whereas Elphidium excavatum and Cassidulina reniforme were dominant in the inner *** organic carbon and the test size of Nonionellina labradorica within the fjord were highly correlated（r=0.97）and both showed a decreasing trend towards the inner *** on the distribution and abundance of Nonionellina labradorica as well as temperature profiles,we suggest that there was little or no major change in the lateral advection of TAW within the fjord in the immediate past.

关键词： West Spitsbergen Current Kongsfjorden Nonionellina labradorica grain size organic carbon stable isotopes temperature

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Sedimentary sources and processes in the eastern Arabian Sea:Insights from environmental magnetism,geochemistry and clay mineralogy

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Geoscience Frontiers 2016年第2期7卷 253-264页

作者： Kumar Avinash P.John Kurian Anish Kumar Warrier R.Shankar T.C.Vineesh rasik ravindra Earth System Science Organization National Centre for Antarctic and Ocean Research(ESSO-NCAOR)Ministry of Earth Sciences(MoES) Department of Marine Geology Mangalore University Earth System Science Organization Ministry of Earth Sciences(MoES)

The spatial distribution patterns of surficial sediment samples from different sedimentary domains （shallow to deep-sea regions） of the eastern Arabian Sea were studied using sediment proxies viz. environmental magnetism, geochemistry, particle size and clay mineralogy. Higher concentrations of magnetic minerals （high Xlf） were recorded in the deep-water sediments when compared with the shallow water sediments. The magnetic mineralogy of one of the shallow water samples is influenced by the presence of bacterial magnetite as evidenced from the XARM/Xlf VS. XARM/Xfd biplot. However, the other samples are catchment-derived. The high correlation documented for Xlf, anhysteretic remanent mag- netisation （XARM） and isothermal remanent magnetisation （IRM） with Al indicates that the deep-sea surflcial sediments are influenced by terrigenous fluxes which have been probably derived from the southern Indian rivers, the Sindhu （the Indus） and the Narmada-Tapti rivers. A lower Mn concentration is recorded in the upper slope sediments from the oxygen minimum zone （OMZ） but a higher Mn/AI ratio is documented in the lower slope and deep-sea sediments. Clay minerals such as illite （24-48.5%）, chlorite （14.1-34.9%）, smectite （10.6-28.7%） and kaolinite （11.9-27.5%） dominate the sediments of shallow and deep-sea regions and may have been derived from different sources and transported by fluvial and aeolian agents. Organic carbon （OC） data indicate a low concentration in the shallow/shelf region （well oxygenated water conditions） and deeper basins （increased bottom-water oxygen concentration and low sedimentation rate）. High OC concentrations were documented in the OMZ （very low bottom-water oxygen concentration with high sedimentation rate）. The calcium carbonate concentration of the surface sediments from the continental shelf and slope regions （〈 1800 m） up to the Chagos-Laccadive Ridge show higher concentrations （average - 58%） when compared to deep basin sediments （average - 44%）.

关键词： Magnetic minerals Major elements Organic carbon Calcium carbonate Terrigenous fluxes Eastern Arabian Sea

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Plant Community and Nutrient Status of the Soils of Schirmacher Oasis,East Antarctica

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Chinese Journal of Polar Science 2008年第1期19卷 63-76页

作者： Shiv Mohan Singh Jagdev Sharma rasik ravindra Purnima Singh National Centre for Antarctic and Ocean research National Research Centre for grapes Purvanchal University Jaunpur India

Investigations on plant community and micronutrient status of Schirmacher Oasis, East Antarctica have been presented in this paper. The dominant plant communities include moss and lichen. The frequency of species occurrence and changes in species composition at different location varied. Thirty-four soil samples were ana- lyzed for chemical properties of the soils of Schirmacher Oasis and Nunatak, East Antarctica. The most common plant species growing throughout the areas of Sehirmacher Oasis and Nunataks are： Candelariella tiara （ lichen ） and Bryum pseudotriquetrum （moss）. Large variations were observed among different soil samples in all the nutri- ents and other measured soil chemical parameters. The soils are characterized by a-cidic pH ranging from 4.42 - 6.80. The mean organic carbon content was 0.62 and ranged from 0. 06 - 1.29%. The electrical conductivity in 1 ： 2 soil water ratio ranged from 0.06 - 1.29. The average content of macronutrient cation, which are ammonium acetate extractable was in the order of Ca 〉 K 〉 Na 〉 Mg. The average content of DTPA extractable micronutrient cations was in the order of Fe 〉 Mn 〉 Cu 〉 Zn. Thirty one out of 34 samples contained less than 0.80 ppm DTPA extractable Zn. Correlation studies revealed that content of macronutrient cations significantly and positively correlated to that of chlorides. Electrical conductivity exhibited significant and positive relationship with pH, K, Ca, Mg, Na and chloride content. Sodium （r =0.876 ＊＊） exhibited highest correlation followed by K （r =0. 831 ＊＊） with chlo- ride content. The correlation coefficient for chlorides was higher with electrical conductivity （r=0.732＊＊） than pH （r =0. 513 ＊＊）. Organic carbon content of the soil was positively correlated with Fe （ r = 0. 442 ＊）. The nutrient status did not appear to be a limiting factor in growth of plants. Lichen and moss community structure and composition in the study area were not related with fertility status of soil. Terres

关键词： Antarctica Schirmacher Oasis Nutrient Lichen Moss.

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Antimicrobial activity of PVP from an Antarctic bacterium, Janthinobacterium sp. Ant5-2, on multi-drug and methicillin resistant Staphylococcus aureus

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Natural Products and Bioprospecting 2012年第3期2卷 104-110页

作者： Jonathan P.HUANG Nazia MOJIB Rakesh R.GOLI Samantha WATKINS Ken B.WAITES rasik ravindra Dale T.ANDERSEN Asim K.BEJ Department of Biology University of Alabama at BirminghamBirminghamAL 35294-1170USA Department of Pathology University of Alabama at BirminghamBirminghamAL 35294-1170USA National Centre for Antarctic&Ocean Research Head Land SadaVasco-da-Gama Goa 403804India Carl Sagan Center for the Study of Life in the Universe SETI InstituteMountain ViewCA 94043USA Red Sea Research Center King Abdullah University of Science and TechnologyThuwal 23955-6900Saudi Arabia

Multiple drug resistant(MDR)and methicillin-resistant Staphylococcus aureus(MRSA)have become increasingly prevalent as a community acquired *** a result limited treatment options are available with conventional synthetic *** natural products with potent antimicrobial activity show promise for developing new drugs against this *** this study,we have investigated the antimicrobial activity of a purple violet pigment(PVP)from an Antarctic bacterium,Janthinobacterium ***5-2 on 15 clinical MDR and MRSA *** colorimetric resazurin assay was employed to determine the minimum inhibitory concentration(MIC90)of PVP against MDR and *** MIC90 ranged between 1.57μg/mL and 3.13μg/mL,which are significantly lower than many antimicrobials tested from natural sources against this *** spectrophotometrically determined growth analysis and total microscopic counts using Live/dead®BacLight™fluorescent stain exhibited a steady decrease in viability of both MDR and MRSA cultures following treatment with PVP at the MIC *** silico predictive molecular docking study revealed that PVP could be a DNA-targeting minor groove binding antimicrobial *** continued development of novel antimicrobials derived from natural sources with the combination of a suite of conventional antibiotics could stem the rising pandemic of MDR and MRSA along with other deadly microbial pathogens.

关键词： natural product bacterial pigment resazurin assay minimum inhibitory concentration(MIC)

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