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| Registros recuperados: 52 | |
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| TRAVERSA,GIANBOSCO; GOMES,CELSO B.; BROTZU,PIERO; BURAGLINI,NICOLETTA; MORBIDELLI,LUCIO; PRINCIPATO,MARIA SPERANZA; RONCA,SARA; RUBERTI,EXCELSO. |
| The Araxá complex (16 km²) comprises carbonatites forming a central core and a complex network of concentric and radial dykes as well as small veins; additionally, it includes mica-rich rocks, phoscorites and lamprophyres. Fenites also occur and are represented by Proterozoic quartzites and schists of the Araxá Group. The petrographic study of 130 borehole samples indicates that the complex is basically made up by two rock-types, carbonatites and mica-rich rocks, and subordinately by a third unit of hybrid composition. Carbonatites range chemically in composition, the most abundant type being magnesiocarbonatites. Dolomite and calcite correspond to the chief constituents, but other carbonate phases, including the Ce-group RE minerals, are also recognized.... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Alkaline rocks; Carbonatites; Geochemistry. |
| Ano: 2001 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652001000100008 |
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| HARTMANN,LÉO A.; ANTUNES,LUCAS M.; ROSENSTENGEL,LEONARDO M.. |
| The Entre Rios mining district produces a large volume of amethyst geodes in underground mines and is part of the world class deposits in the Paraná volcanic province of South America. Two producing basalt flows are numbered 4 and 5 in the lava stratigraphy. A total of seven basalt flows and one rhyodacite flow are present in the district. At the base of the stratigraphy, beginning at the Chapecó river bed, two basalt flows are Esmeralda, low-Ti type. The third flow in the sequence is a rhyodacite, Chapecó type, Guarapuava subtype. Above the rhyodacite flow, four basalt flows are Pitanga, high-Ti type including the two mineralized flows; only the topmost basalt in the stratigraphy is a Paranapanema, intermediate-Ti type. Each individual flow is uniquely... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Amethyst geode; Entre Rios mining district; Paraná volcanic province; Geochemistry; Gamma-spectrometry. |
| Ano: 2014 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652014000100187 |
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| GUIMARÃES,JOSÉ T.F.; SAHOO,PRAFULLA K.; SOUZA-FILHO,PEDRO W.M.; FIGUEIREDO,MARIANA M.J. COSTA DE; REIS,LUIZA S.; SILVA,MARCIO S. DA; RODRIGUES,TARCÍSIO M.. |
| ABSTRACT Down-core changes in sedimentary facies, elemental geochemistry, pollen, spore, δ13C, δ15N and radiocarbon records from a filled lake, named R4, of the Serra Sul dos Carajás were used to study the relationship between the paleomorphological and paleoecological processes and their significance for Holocene paleoclimatology of the southeast Amazonia. The sediment deposition of the R4 lake started around 9500 cal yr BP. Increase of detrital components from 9500 to 7000 cal yr BP suggests high weathering of surrounding catchment rocks and soils, and deposition into the lake basin under mudflows. At that time, montane savanna and forest formation were already established suggesting predominance of wet climate. However, from 7000 to 3000 cal yr BP, a... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Amazon Forest; Canga vegetation; Palynology; Carbon and nitrogen isotopes; Geochemistry. |
| Ano: 2019 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652019000400502 |
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| Carrera Villacrés, David Vinicio. |
| El desarrollo geológico de la Sierra Madre Oriental y la Plataforma Valles-San Luis, estados de Querétaro y San Luis Potosí en donde se localiza la cuenca evaporítica de Río Verde-Matehuala, formó una diversidad salina de aguas y suelos. La salinidad causa baja fertilidad y deterioro en los campos agrícolas, solamente el manantial de Media Luna riega aproximadamente 5000 ha, lo que hace relevante su estudio. Los objetivos de este trabajo fueron conocer la salinidad cuantitativa y cualitativa tanto en aguas como en suelos, además, determinar la vía evolutiva que toman las aguas en la meteorización por evaporación de las mismas como un ejemplo del calentamiento global y, relacionar los efectos de la salinidad de las aguas y suelos sobre los cultivos. La... |
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Palavras-chave: Geoquímica; Evolución de las aguas; Calentamiento global; Sodicidad; Geochemistry; Water evolution; Global warming; Sodicity; Doctorado; Hidrociencias. |
| Ano: 2011 |
URL: http://hdl.handle.net/10521/476 |
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| Carrera Villacrés, David Vinicio. |
| El desarrollo geológico de la Sierra Madre Oriental y la Plataforma Valles-San Luis, estados de Querétaro y San Luis Potosí en donde se localiza la cuenca evaporítica de Río Verde-Matehuala, formó una diversidad salina de aguas y suelos. La salinidad causa baja fertilidad y deterioro en los campos agrícolas, solamente el manantial de Media Luna riega aproximadamente 5000 ha, lo que hace relevante su estudio. Los objetivos de este trabajo fueron conocer la salinidad cuantitativa y cualitativa tanto en aguas como en suelos, además, determinar la vía evolutiva que toman las aguas en la meteorización por evaporación de las mismas como un ejemplo del calentamiento global y, relacionar los efectos de la salinidad de las aguas y suelos sobre los cultivos. La... |
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Palavras-chave: Geoquímica; Evolución de las aguas; Calentamiento global; Sodicidad; Geochemistry; Water evolution; Global warming; Sodicity; Doctorado; Hidrociencias. |
| Ano: 2011 |
URL: http://hdl.handle.net/10521/476 |
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| Khripounoff, Alexis; Vangriesheim, Annick; Crassous, Philippe; Segonzac, Michel; Colaco, Ana; Desbruyeres, Daniel; Barthelemy, Roxane. |
| In order to provide information about the export and the distribution of hydrothermal particulate material to the surrounding deep ocean, four moorings were deployed in the vicinity of the hydrothermal Rainbow vent field (Mid-Atlantic Ridge, 36 degrees 14'N, 2250 m depth). The first mooring was a sediment trap with a current meter deployed at 2 m from a chimney of the Rainbow vent field and 1.5 m above the bottom (a.b.) for 16 days. It represented the reference for the initial composition of particles produced by the vent. The total mean mass particle flux (6.9 g m(-2) d(-1)) was distinctly higher than the flux measured at the shallower hydrothermal vents on the MAR segment. This particulate flux showed a high temporal variation at the scale of a few days... |
| Tipo: Text |
Palavras-chave: Zooplankton; Biochemistry; Geochemistry; Particle flux; Hydrothermal vent. |
| Ano: 2001 |
URL: https://archimer.ifremer.fr/doc/2001/publication-801.pdf |
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| Revillon, Sidonie; Guillou, Herve; Maury, Rene C.; Chauvel, Catherine; Aslanian, Daniel; Pelleter, Ewan; Scao, Vincent; Loubrieu, Benoit; Patriat, Martin. |
| The Marquesas Island chain in Polynesia is quite unusual because the alignment of the islands on the Pacific oceanic plate (N40°W) does not follow the plate motion in the region (N65°W). The exact location of the active hotspot is unknown but has been predicted to underlie the Marquesas Fracture Zone Ridge. Nevertheless, no concrete evidence exists. Here, we document the occurrence on this ridge of fresh tephrites dated at ~ 92 ka by the 40Ar-39Ar method. The lavas dredged on a small seamount have trace element contents and Sr, Nd, Pb isotopic compositions typical of the southwest Marquesas Islands, the Fatu Hiva group. This discovery demonstrates that the Marquesas plume is still active and it puts new constraints on its present location. It also supports... |
| Tipo: Text |
Palavras-chave: Submarine volcanism; Ar-40-Ar-39 ages; Geochemistry; Plume; Marquesas; French Polynesia. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00407/51832/52431.pdf |
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| Ruffine, Livio; Geli, Louis. |
| Summary of Marsitecruise The scientific cruise MARSITECRUISE of R/V Pourquoi pas? Took place from 28 October to 17 November 2014. Part of the operations were carried out within the frame of the MARSITE programme supported by the European Union, which aims at better understanding the behaviour of the North Anatolian fault in the Marmara sea in view of improving the assessment of the seismic hazard weighing on the Istanbul region. Coordinated by the Observatory of the University of Kandilli (KOERI, based in Istanbul), MARSITE groups 23 partners and includes different components: land, spatial and marine. The marine operations of the programme were coordinated by Ifremer and conducted using Italian (R/V Urania) and French (R/V Pourquoi pas?) naval means.... |
| Tipo: Text |
Palavras-chave: Sea of Marmara; Geochemistry; Seismicity. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00453/56480/58177.pdf |
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| Sicre, Ma; Bard, E; Ezat, U; Rostek, F. |
| The C(37)-C(39) alkenones were quantified in suspended particulate matter obtained from the surface waters of the North Atlantic, including the Nordic seas, over a temperature range of 4degrees20 C. U(37)(K') values were linearly correlated to temperature over the entire range covered by our data set, i.e., 420 C (U(37)(K') = 0.027T + 0.036, r(2) = 0.97). The compilation of water column data from the Atlantic, Pacific, and Southern Ocean and Mediterranean Sea suggests that the linear model may not be the best function for fitting U(37)(K') and in situ temperature values. It also shows that suspended matter data from warm waters (T >20degreesC) are still needed to constrain the equation of the global curve. High abundances of C(37: 4) were found in the... |
| Tipo: Text |
Palavras-chave: Alkenones; Paleotemperature; Calibration; Atlantic Ocean; Plankton; Geochemistry; Marine geochemistry; Global change; Biogeochemical processes (4805); Oceanography; Paleoceanography. |
| Ano: 2002 |
URL: https://archimer.ifremer.fr/doc/00223/33393/31866.pdf |
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| Beck, Pierre; Chaussidon, M; Barrat, J.a.; Gillet, Ph.; Bohn, Marcel. |
| Ion-microprobe was used to measure Li abundances and isotopic compositions in pyroxenes from three Martian meteorites belonging to the nakhlite family. The profiles performed across augite crystals from Northwest Africa 817 show a large isotopic zoning from crystal cores (delta Li-7 similar to 0 parts per thousand) to rims (delta Li-7 similar to +20 parts per thousand) while Li abundances are almost constant (similar to 9.2 mu g/g). Unlike NWA 817, the pyroxene studied in the Miller Range 03346 nakhlite shows a zoning in Li abundance, with concentrations increasing from similar to 2.5 mu g/g in the core to similar to 9 mu g/ g in the rim. The augite rim (delta Li-7 = +7 parts per thousand) is slightly enriched in Li-7 with regard to the core (delta Li-7 =... |
| Tipo: Text |
Palavras-chave: Magma; Pyroxene; Lithium; Geochemistry; Mars planet; Isotopic composition. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-1955.pdf |
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| Seo, Inah; Lee, Yuri; Lee, Yong Il; Yoo, Chan Min; Hyeong, Kiseong. |
| This paper investigates paleoceanographic changes at a central equatorial Pacific site (6 degrees 40N, 177 degrees 28W) since the last glacial maximum using planktic foraminifera assemblages, together with the oxygen isotope (O-18) and Mg/Ca compositions of three species (Globigerinoides sacculifer, Pulleniatina obliquiloculata, and Globorotalia tumida) that dwell in the mixed layer, upper thermocline, and lower thermocline, respectively. While the Mg/Ca-derived temperatures of the mixed layer and lower thermocline varied within a narrow range from 18 ka onward, the upper thermocline temperature increased by as much as 3 degrees C during the last deglaciation (18-12 ka) with a simultaneous decrease of O-18. These changes are best explained by an enhanced... |
| Tipo: Text |
Palavras-chave: Planktic foraminifera; Geochemistry; Micropaleontology; Paleoceanography; Intertropical Convergence Zone; Last deglaciation. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00496/60721/65271.pdf |
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| Registros recuperados: 52 | |
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