Consulta: subjectFacets:"Geochemistry"
Registros recuperados: 52
Data/hora: 12/06/2024 00:42:51

Salinidad en suelos y aguas superficiales y subterráneas de la cuenca evaporítica de Río Verde-Matehuala, San Luis Potosí.
Provedor de dados: 32
Autores: 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...
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

Salinidad en suelos y aguas superficiales y subterráneas de la cuenca evaporítica de Río Verde-Matehuala, San Luis Potosí.
Provedor de dados: 32
Autores: 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...
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

Caracterização física e aspectos geoquímicos de dois solos da Península Keller, Ilha Rei George, Antártica Marítima.
Provedor de dados: 14
Autores: ALBUQUERQUE FILHO, M. R.; SCHAEFER, C. E. G. R.; SIMAS, F. B. N.; PEREIRA, V. V.; GUERRA, M. B. B.
bitstream/CPAC-2009/26885/1/p2005_61.pdf
Tipo: Fôlder / Folheto / Cartilha (INFOTECA-E)
Palavras-chave: Soil testing.; Análise do Solo; Geoquímica; Mineralogia; Solo.; Geochemistry; Mineralogy; Soil.
Ano: 2006
URL: http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/569491

A influência da mineralogia na evolução micromorfológica do colapso em saprólito e latossolo.
Provedor de dados: 14
Autores: CARDOSO, F. B. da F.; MARTINS, E. de S.; CARVALHO, J. C. de.
Resumo: Este trabalho mostra a aplicação de técnicas modernas de micromorfologia e mineralogia no desenvolvimento de um modelo evolutivo do colapso em solos tropicais profundamento intemperizados. Abstract: This work exibition the application of modern techniques of micromorphology and mineralogy in the development of an evolutionary model of the collapse in deeply weathering tropical soils.
Tipo: Boletim de Pesquisa e Desenvolvimento (INFOTECA-E)
Palavras-chave: ECOSOL170; Micromorfologia; Colapso; Micromorphology; Collapse; Soil testing.; Análise do Solo; Cerrado; Geoquímica; Mineralogia; Solo.; Geochemistry; Mineralogy; Soil.
Ano: 2002
URL: http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/567945

Origin and significance of tourmalinites and tourmaline-bearing rocks of Menderes Massif, western Anatolia, Turkey
Provedor de dados: 5
Autores: Yucel-ozturk, Yesim; Helvaci, Cahit; Palmer, Martin R.; Ersoy, E. Yalcin; Freslon, Nicolas.
In the western central portion of Anatolia lies the Menderes Massif – a large metamorphic crystalline complex made of Neoproterozoic to Precambrian basement rocks overlain by Palaeozoic to early Tertiary metasedimentary rocks, and with a multistage metamorphic evolution developed from the late Neo-Proterozoic to Eocene. We have undertaken a study of the petrology, geochemistry and boron isotope composition of these tourmaline occurrences aiming to constrain the processes responsible for the enrichment of boron and other fluid mobile elements in the Menderes Massif. The dispersed tourmaline has chemical and boron isotope compositions typical of a continental crust setting, but while some of the tourmalinites display similar signatures, others have heavier...
Tipo: Text
Palavras-chave: Tourmalinites; Geochemistry; Boron isotope; Menderes Massif; Western Anatolia; Turkey.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00250/36121/34675.pdf

Taxonomic Re-Investigation and Geochemical Characterization of Reid’s (1974) Species of     Spiniferites     from Holotype and Topotype Material
Provedor de dados: 5
Autores: Gurdebeke, Pieter R.; Mertens, Kenneth; Bogus, Kara; Marret, Fabienne; Chomerat, Nicolas; Vrielinck, Henk; Louwye, Stephen.
The genus Spiniferites currently encompasses 142 dinoflagellate cyst species. Some Spiniferites species are difficult to identify because of an incomplete or doubtful description, and/or substandard iconography. This study re-describes and re-illustrates the Spiniferites holotypes first described by Reid in 1974 Reid PC. 1974. Gonyaulacacean dinoflagellate cysts from the British Isles. Nova Hedwigia. 25:579–637. [Google Scholar]. It also discusses topotype material from surface sediments recovered from British estuaries, and attempts to provide further constraints on the classification of species in this genus using the geochemical characterization of their cyst walls. Reid described four new Spiniferites species: Spiniferites belerius, Spiniferites...
Tipo: Text
Palavras-chave: Dinoflagellate cyst; Redescription; Taxonomy; Geochemistry; Cyst wall composition; FTIR; Dinosporin.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00471/58306/60847.pdf

Iron oxide formation in the active oxidation front above sapropel S1 in the eastern Mediterranean Sea as derived from low-temperature magnetism
Provedor de dados: 5
Autores: Passier, Hf; Dekkers, Mj.
Low-temperature magnetic properties of eastern Mediterranean sediments from a box-core have been investigated. This box-core contains the present-day oxic-suboxic boundary that is situated at the top of the relic of the youngest sapropel (S1). The upper half of sapropel S1 has been oxidized, and Fe oxides have precipitated in the oxidized sapropel. Zero-field-cooling (ZFC) and field-cooling (FC) saturation remanent magnetization (M-r; induced in a field of 2.5 T at 20 K after cooling from 300 K with or without the 2.5 T field) was measured during warming to 300 K. An M (r) imparted at room temperature (RTSIRM) was cycled to 20 K as well. The difference between ZFC and FC curves around the Verwey transition, as estimated by the parameter delta(FC)...
Tipo: Text
Palavras-chave: Geochemistry; Low-temperature magnetism; Magnetite; Marine sediments; Oxidation; Sediment magnetism.
Ano: 2002
URL: https://archimer.ifremer.fr/doc/00223/33399/31887.pdf

Extreme source heterogeneity and complex contamination patterns along the Cameroon Volcanic Line: New geochemical data from the Bamoun plateau
Provedor de dados: 5
Autores: Ziem A. Bidias, Luc Achille; Chazot, Gilles; Moundi, Amidou; Nonnotte, Philippe.
We investigated mafic and felsic volcanic rocks from the Bamoun plateau, a magmatic province located north of Mount Cameroon, in the continental part of the Cameroon Volcanic Line (CVL). Basalts and dacites were probably emplaced more than 40 Ma ago, while basanites represent very young volcanic eruptions. Among the basalts, some of them have suffered crustal contamination during their uprise through the continental crust, and their primary trace element and isotopic compositions have been slightly modified. The formation of the dacites was also accompanied by some crustal contamination. Non-contaminated rocks show that the oldest magmas are transitional basalts formed by relatively high degrees of partial melting of a moderately enriched mantle source,...
Tipo: Text
Palavras-chave: Cameroon Volcanic Line; Geochemistry; Mantle source; Crustal contamination; Basalt.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00638/74996/75730.pdf

Dynamic storage of glacial CO2 in the Atlantic Ocean revealed by boron [CO32-] and pH records
Provedor de dados: 5
Autores: Chalk, T. B.; Foster, G. L.; Wilson, P. A.
The origin and carbon content of the deep water mass that fills the North Atlantic Basin, either Antarctic Bottom Water (AABW) or North Atlantic Deep Water (NADW) is suggested to influence the partitioning of CO2 between the ocean and atmosphere on glacial-interglacial timescales. Fluctuations in the strength of Atlantic meridional overturning circulation (AMOC) have also been shown to play a key role in global and regional climate change on timescales from annual to millennial. The North Atlantic is an important and well-studied ocean basin but many proxy records tracing ocean circulation in this region over the last glacial cycle are challenging to interpret. Here we present new B/Ca-[CO32-] and boron isotope-pH data from sites spanning the North...
Tipo: Text
Palavras-chave: Boron; Geochemistry; Palaeoceanography; Carbonate system; Glacial; Atlantic.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00496/60812/64631.pdf

Climatic evolution of the central equatorial Pacific since the Last Glacial Maximum
Provedor de dados: 5
Autores: 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

From intracratonic extension to mature spreading in back arc basins: Examples from the Okinawa, Lau, North Fiji basins
Provedor de dados: 5
Autores: Auzende, Jean-marie; Boespflug, Xavier; Bougault, Henri; Dosso, Laure; Foucher, Jean-paul; Joron, Jean-louis; Ruellan, Etienne; Sibuet, Jean-claude.
Three cruises (POP 1, SEAPSO 3 and SEAPSO 4) carried out during the "Tour du Monde" of the R.V. Jean Charcot allow us to obtain new structural and geochemical data for the Okinawa, North Fiji and Lau basins. Taken together, the structural and geochemical data illustrate a difference in evolution stages of these sites. The less evolved stage is represented by the Okinawa basin, where accretion is evidenced only by volcanic intrusion into a thinned continental crust. The most evolved stage is illustrated in the North Fiji basin, where the present-day accretion can be directly compm·ed to the East Pacific Ridge. The Lau basin displays an intem1ediate stage with a complex system of accretionary ridges. This difference in the evolution stage is translated in...
Tipo: Text
Palavras-chave: Ouest Pacifique; Bassins arriere arc; Structure; Accretion; Geochimie; West Pacific; Back arc basins; Structure; Accretion; Geochemistry.
Ano: 1990
URL: http://archimer.ifremer.fr/doc/00119/23058/20893.pdf

Reconstitution de la variabilité naturelle climatique et océanographique dans l’estuaire et le golfe du Saint-Laurent au cours des 10,000 dernières années
Provedor de dados: 5
Autores: Casse, Marie.
L’estuaire et le golfe du Saint-Laurent (EGSL, Est du Canada) sont des milieux très dynamiques d’un point de vue sédimentaire. Pourtant, les voies de propagation des sédiments fluviaux ainsi que l’origine et le mélange des apports sédimentaires en milieu marin ne sont pas bien documentés dans cette zone. Or, ces connaissances sont fondamentales pour déterminer les sources principales des apports terrigènes et mieux comprendre la dynamique de ce système sédimentaire. Dans ce contexte, les propriétés physiques, la distribution granulométrique, la minéralogie, les éléments majeurs et traces, et les isotopes radiogéniques (néodyme et strontium) d’un ensemble de sédiments de surface et de carottes sédimentaires de l’EGSL ont été étudiées dans cette thèse afin...
Tipo: Text
Palavras-chave: Estuary and gulf of St.Lawrence; Holocene; Laurentide Ice Sheet; Relative sea level; Sedimentary dynamic; Mineralogy; Geochemistry; Radiogenic isotopes; Rare earth elements.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00494/60611/64095.pdf

Millennial scale persistence of organic carbon bound to iron in Arctic marine sediments
Provedor de dados: 5
Autores: Faust, Johan C.; Tessin, Allyson; Fisher, Ben J.; Zindorf, Mark Sebastian; Papadaki, Sonia; Hendry, Katharine R.; Doyle, Katherine A.; März, Christian.
Burial of organic material in marine sediments represents a dominant natural mechanism of long-term carbon sequestration globally, but critical aspects of this carbon sink remain unresolved. Investigation of surface sediments led to the proposition that on average 10-20% of sedimentary organic carbon is stabilised and physically protected against microbial degradation through binding to reactive metal (e.g. iron and manganese) oxides. Here we examine the long-term efficiency of this rusty carbon sink by analysing the chemical composition of sediments and pore waters from four locations in the Barents Sea. Our findings show that the carbon-iron coupling persists below the uppermost, oxygenated sediment layer over thousands of years. We further propose that...
Tipo: Text
Palavras-chave: Carbon cycle; Geochemistry.
Ano: 2021
URL: https://archimer.ifremer.fr/doc/00675/78755/80923.pdf

Les nodules du pacifique central dans leur environnement géologique CAMPAGNES COPANO - 1979
Provedor de dados: 5
Autores: Pautot, Guy; Hoffert, Michel.
The cruises named COPANO have been undertaken during the summer 1979 on the R. V. Le Suroit of the CNEXO, as a part of an international research program I.C.I.M.E. The objective of this project was to study relatively small zones (a few km2) and to establish a relationship between characteristics of the manganese nodules and their environment. During the COPANO cruises, five zones have been studied: two in the northern Pacific, two in the southern Pacific and finally one in the equatorial Pacific. All the zones are centered on the longitude 134° Wand therefore their symmetry to the highly productive equatorial zone may be tested. As one of the results of the cruises is the relation between nodules and the bottom soil, established by sediment-sampling and a...
Tipo: Text
Palavras-chave: Géochimie; Cartographie; Geologie; Fonds marin; Environnement; Nodules; Geochemistry; Mapping; Structural geology; Environmental impact; Nodule.
Ano: 1984
URL: http://archimer.ifremer.fr/doc/1984/rapport-1144.pdf

Alkenone distributions in the North Atlantic and Nordic sea surface waters
Provedor de dados: 5
Autores: 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 &gt;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

New structural and geochemical observations from the Pacific-Antarctic Ridge between 52°45'S and 41°15'S
Provedor de dados: 5
Autores: Klingelhoefer, Frauke; Ondreas, Helene; Briais, A; Hamelin, C; Dosso, Laure.
We investigated the morphology and structure of the Pacific-Antarctic Ridge between 52 degrees 45'S and 41 degrees 15'S during the Pacantarctic2 cruise using multibeam echosounder together with gravity measurements and dredges. Analysis of the bathymetric, gravity and geochemical data reveal three ridge segments separated by overlapping spreading centers south of the Menard transform fault (MTF) and five segments north of it. Calculation of the cross-sectional area allows quantification of the variation in size of the axial bathymetric high. Together with the calculation of the mantle Bouguer anomaly, these data provide information about variations in the temperature of the underlying mantle or in crustal thickness. Areas with hotter mantle are found north...
Tipo: Text
Palavras-chave: Mantle Bouguer anomaly; Temperature variations; Geochemistry; Gravity; Bathymetry; Ridge segment.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/publication-2108.pdf

Evidence for major-element heterogeneity in the mantle source of abyssal peridotites from the Southwest Indian Ridge (52 degrees to 68 degrees E)
Provedor de dados: 5
Autores: Seyler, M; Cannat, M; Mevel, C.
A suite of 53 samples of mantle spinel lherzolites and harzburgites dredged at 13 sites between 52degreesE and 68degreesE along the Southwest Indian Ridge has been studied for petrography and mineral major element chemistry. Results show that the residual mantle beneath this very slow-spreading/cold ridge is strongly heterogeneous in modal and mineral compositions at local and regional scales and underwent greater extents of melting than predicted by melting model and by compositions of the basalts dredged with the peridotites. Along-axis, the peridotite compositional variability defines a concave pattern with increasing depletion at both ends of the studied section (e. g., approaching Rodrigues Triple Junction to the East and Gallieni fracture zone to the...
Tipo: Text
Palavras-chave: Peridotite midocean ridge Indian Ocean petrology mantle heterogeneity geochemistry : composition of the mantle marine geology and geophysics : midocean ridge processes information related to geographic region : Indian Ocean history of geophysics : volcanology; Geochemistry; And petrology.
Ano: 2003
URL: https://archimer.ifremer.fr/doc/00224/33506/31941.pdf

Temporal magma source changes at Gaua volcano, Vanuatu island arc
Provedor de dados: 5
Autores: Beaumais, Aurelien; Bertrand, Herve; Chazot, Gilles; Dosso, Laure; Robin, Claude.
Gaua Island (also called Santa Maria), from the central part of the Vanuatu arc, consists of a large volcano marked by a caldera that hosts the active Mount Garet summit cone. In this paper, a geochemical study including Sr, Nd, Pb and Hf isotopic compositions of 25 lavas emitted since 1.8 Ma is presented, with a focus on the volcanic products that preceded (old volcanics, main cone and pyroclastic series) and followed (Mount Garet) the caldera forming event.  All lavas show an island arc signature with enrichment in LILE and depletion in HFSE. Post-caldera lavas define a medium-K calc-alkaline trend, whereas lavas from the former main cone have high-K calc-alkaline compositions. Compared to the pre-caldera volcanic suite, the Mount Garet lavas have...
Tipo: Text
Palavras-chave: Gaua; Vanuatu; Geochemistry; Isotopes; Subduction; Mantle source.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00319/43052/42557.pdf

Li isotopic variations in single pyroxenes from the Northwest Africa 480 shergottite (NWA 480): a record of degassing of Martian magmas?
Provedor de dados: 5
Autores: Beck, Pierre; Barrat, J; Chaussidon, M; Gillet, P; Bohn, Marcel.
Lithium abundances and isotopic compositions were measured by ion microprobe in individual grains of pyroxene, and in a few maskelynites and Ca-phosphates grains, from the Martian meteorite Northwest Africa 480 (NWA 480).  In pyroxenes Li abundances are nearly constant from core to rim with concentrations ranging between 3 and 4 mug/g. In contrast, a significant isotopic zoning is observed with delta(7)Li values increasing within single crystals from similar to -17parts per thousand in the core to similar to +10parts per thousand in the rim, most of the variability being observed in the core. Plagioclase (now maskelynite) and phosphate crystals, which co-crystallized with the pyroxene rims, display similar delta(7) Li values. Because of the incompatible...
Tipo: Text
Palavras-chave: Mars planet; Magma; Pyroxene; Isotopic composition; Lithium; Geochemistry.
Ano: 2004
URL: http://archimer.ifremer.fr/doc/2004/publication-735.pdf

Reconciling down core anticorrelation of diatom carbon and nitrogen isotopic ratios from the Southern Ocean
Provedor de dados: 5
Autores: Crosta, X; Shemesh, A.
[1] Oceanic nutrient cycling in the Southern Ocean is supposed to have an important impact on glacial-interglacial atmospheric CO(2) changes and global climate. In order to characterize such nutrient cycling over the last two climatic cycles we investigated carbon and nitrogen isotopic ratios of diatom-bound organic matter (delta(13)C(diat) and delta(15)N(diat)- respectively) in two cores retrieved form the Atlantic and Indian sectors of the Antarctic Ocean. The two cores show the same isotopic patterns. The delta(13)C(diat) values are depleted during glacial periods and enriched during interglacial periods, indicating lower productivity during cold times. The delta(15)N(diat) values are enriched during glacial periods and depleted during interglacial...
Tipo: Text
Palavras-chave: Southern Ocean; Paleoceanography; Geochemistry; Diatoms.
Ano: 2002
URL: https://archimer.ifremer.fr/doc/00223/33402/31859.pdf

Particle flux in the Rainbow hydrothermal vent field (Mid-Atlantic Ridge): Dynamics, mineral and biological composition
Provedor de dados: 5
Autores: 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

Magnetic properties and geochemistry of the active oxidation front and the youngest sapropel in the eastern Mediterranean Sea
Provedor de dados: 5
Autores: Passier, Hf; De Lange, Gj; Dekkers, Mj.
Magnetic properties (IRM, ARM, chi (in), S-ratio at 0.3 T, room temperature (RT) hysteresis and thermomagnetic curves) and geochemical data (Fe, S, Mn, Al, Ti, organic C) were studied in two eastern Mediterranean boxcores (ABC26 and BC19) at a resolution of 3-5 mm. The boxcores contain sapropel S1 (9-6 kyr BP) at a few decimetres below seafloor. The magnetic fraction consists predominantly of single-domain (SD) to pseudo-single-domain (PSD) magnetite in the entire cores. The original input of magnetic grains comes from two sources: aeolian dust (both cores) and volcanic ash from the Minoan eruption of Santorini (core BC19 only). Non-steady-state diagenesis has changed the magnetic mineralogy considerably in these alternating organic-rich /organic-poor...
Tipo: Text
Palavras-chave: Geochemistry; Magnetite; Marine sediments; Mediterranean Sea; Oxidation; Sediment magnetism.
Ano: 2001
URL: https://archimer.ifremer.fr/doc/00221/33184/31805.pdf

L'argent (Ag, nanoAg) comme contaminant émergeant dans l'Estuaire de la Gironde : évaluations scientifiques et gouvernance des risques
Provedor de dados: 5
Autores: Salles, Denis; Roumezi, Alexis; Lanceleur, Laurent; Schaefer, Jorg; Petit, Jerome; Blanc, Gerard; Coynel, Alexandra; Chiffoleau, Jean-francois; Auger, Dominique.
This article presents the results of multidisciplinary research (geochemistry, sociology) into the increasing concentrations of silver (Ag and nanoAg) in the environment and their potential impact on aquatic environments. We investigate simultaneously the risk of contamination of these environments by silver and the process of the social and political construction of this risk by water managers, health authorities, agencies and committees responsible for expert evaluations, environmental associations, and potential users of silver or nano-silver. Four updated models of risk construction allow us to understand the logic of arguments mobilized at this stage of the emerging risk. This interdisciplinary cooperation opens up possibilities for dealing with some...
Tipo: Text
Palavras-chave: Environment; Estuaries; Geochemistry; Interdisciplinary communication; Nanotechnology; Risk assessment; Risk management; Silver; Sociology; Water pollutants.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00156/26736/24939.pdf

Caractérisation physique et géochimique d'hydrates de gaz d'environnements géologiques différents. Apport des techniques de Diffraction X Synchrotron et de Spectroscopie Raman. Contribution à l'étude de leur origine, formation et stabilité sur les marges
Provedor de dados: 5
Autores: Bourry, Christophe.
Clathrate hydrates are inclusion compounds consisting of an ice-like network of water cages surrounding occluded guest molecules. They occur beneath the oceans and in polar regions, where low temperature and high pressure conditions prevail. Natural gas hydrates, mainly composed of methane occur worldwide and may contain huge natural gas amount, but they can also play an important role in continental slope stability or climate change, due to the potentially enormous "greenhouse" feedback effect of methane. The knowledge of their occurrence in the natural environment, their physical, chemical or thermodynamical properties is essential to prevent geohazards, to anticipate their role in climate change or to develop technologies to take advantage of this...
Tipo: Text
Palavras-chave: X Ray synchrotron diffraction; Raman spectroscopy; Geochemistry; Gas hydrate; Eau interstitielle; Diffraction X synchrotron; Spectroscopie Raman; Géochimie; Hydrate de gaz.
Ano: 2008
URL: http://archimer.ifremer.fr/doc/2008/these-6236.pdf

Temporal source evolution and crustal contamination at Lopevi Volcano, Vanuatu Island Arc
Provedor de dados: 5
Autores: Beaumais, Aurelien; Chazot, Gilles; Dosso, Laure; Bertrand, Herve.
Here we present a new geochemical study of Lopevi volcano, one the most active volcanoes in the Vanuatu island arc. We focus on the temporally well-defined sequence of lava flows emitted since 1960, and for the first time, on pre-1960 volcanic products, including high-MgO basalts and felsic andesites, the most evolved lavas sampled so far on this island. This work reports the first Pb and Hf isotopic study of lavas from Lopevi island. These lavas display correlations between differentiation indexes such as SiO2 content and isotopic ratios. The felsic andesites extend the known correlations with both the least (Sr-Pb) and the most (Nd-Hf) radiogenic isotopic compositions on the island. Our results confirm that the rising magma interacted with the sub-arc...
Tipo: Text
Palavras-chave: Lopevi; Vanuatu; Geochemistry; Isotopes; Subduction; Mantle source.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00167/27801/26223.pdf

Neodymium isotopic composition and rare earth element concentrations in the deep and intermediate Nordic Seas: Constraints on the Iceland Scotland Overflow Water signature
Provedor de dados: 5
Autores: Lacan, F; Jeandel, C.
Neodymium isotopic composition and rare earth element concentrations were measured in seawater samples from eleven stations in the Nordic Seas. These data allow us to study how the Iceland Scotland Overflow Water ( ISOW) acquires its neodymium signature in the modern ocean. The waters overflowing the Faroe Shetland channel are characterized by epsilon(Nd) = -8.2 +/- 0.6, in good agreement with the only other data point, published 19 years ago. In the Greenland and Iceland Seas the water masses leading to the formation of the ISOW display lower neodymium isotopic composition, with epsilon(Nd) around -11 and -9, respectively. Since no water masses in the Nordic Seas are characterized by epsilon(Nd) &gt; -8, the radiogenic signature of the ISOW likely...
Tipo: Text
Palavras-chave: Iceland Scotland Overflow Water; Neodymium isotopic composition; Nordic Seas; North Atlantic; Rare earth; Sediment water mass interactions; Paleoceanography; Water masses; Geochemistry.
Ano: 2004
URL: https://archimer.ifremer.fr/doc/00228/33924/32308.pdf

Young Marquesas volcanism finally located
Provedor de dados: 5
Autores: 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

Comportement chimique et geochimique des elements a l'état de traces dans l''estuaire de la Seine: Une synthese des resultats
Provedor de dados: 5
Autores: Guegueniat, P.
Five topics are developed in this synthesis: (1) multi elements analysis in geochemistry; (2) iron geochemical behavior; (3) complexing properties of waters; (4) copper behavior in estuarine waters; (5) impact of sediment dynamics on dissolved metals concentration.
Tipo: Text
Palavras-chave: Geographical distribution; Radiochemistry; Brackishwater pollution; Sediment dynamics; Dissolved chemicals; Heavy metals; Geochemistry; Physicochemical properties; Trace elements.
Ano: 1985
URL: http://archimer.ifremer.fr/doc/1985/acte-1290.pdf

Modern sedimentation and geochemical imprints in sediments from the NW Madagascar margin
Provedor de dados: 5
Autores: Pastor, Lucie; Brandily, Christophe; Schmidt, S.; Miramontes, E.; Péron, Maela; Appere, Dennis; Chéron, Sandrine; Boissier, Audrey; Jouet, Gwenael.
The NW Madagascar continental margin receives high loads of terrigenous particulate organic matter during the wet season and especially linked to extreme events, originating from two major rivers, the Betsiboka and the Mahavavy Rivers. This particulate matter contains a high content of iron minerals from the weathering of red ferruginous/ferralitic soils of Madagascar. The presence of pockmarks, i.e. gas or fluid expulsion features on the continental slope, testifies to past/present methane migration through the sedimentary column, associated with early diagenetic processes. This study globally aims at deciphering the interactions between episodic sedimentation and geochemical processes influenced by fluids upward migration, using a sediment trap mooring...
Tipo: Text
Palavras-chave: Episodic sedimentation; Madagascar margin; Betsiboka river; Mahavavy river; Progradation; Methane; Geochemistry; Sediment.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00628/73964/73323.pdf

MARSITECruise Report. 2014 1st ‐ 13th November ‐ Leg 2
Provedor de dados: 5
Autores: 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

Age, geochemical characteristics and petrogenesis of Cenozoic intraplate alkaline volcanic rocks in the Bafang region, West Cameroon
Provedor de dados: 5
Autores: Ngongang, Nicaise Blaise Tchuimegnie; Kamgang, Pierre; Chazot, Gilles; Agranier, Arnaud; Bellon, Herve; Nonnotte, Philippe.
The origin of the volcanism in the Cameroon Volcanic Line and the nature of its mantle sources are still highly controversial. We present major and trace element compositions as well as Sr-Nd-Pb-Hf isotopic results on mafic and intermediate lavas from the Bafang area in the central part of the Cameroon Volcanic Line. The lavas range from basanites and basalts to hawaiites and mugearites with an alkaline affinity and were emplaced between 10 and 6 Ma ago. The evolution from basalts and basanites to more differentiated rocks involved fractionation of olivine, clinopyroxene and Fe-Ti oxides, but the isotopic compositions show that crustal contamination processes affected some magmas during their ascent in the crust. Basalts and basanites originated from a...
Tipo: Text
Palavras-chave: Cameroon Volcanic Line; Geochemistry; Magmatism; Mantle source.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00221/33255/32158.pdf

Ocean biogeochemistry: Carbon at the coastal interface
Provedor de dados: 5
Autores: Gruber, Nicolas.
The extent to which coastal-ocean regions act as a sink for carbon dioxide has been enigmatic. An estimate based on more than 3 million observations suggests a smaller sink than was thought, concentrated at high latitudes.
Tipo: Text
Palavras-chave: Ocean sciences; Geochemistry.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00292/40341/38938.pdf

Trace of the Kerguelen mantle plume: Evidence from seamounts between the Kerguelen Archipelago and Heard Island, Indian Ocean
Provedor de dados: 5
Autores: Weis, D; Frey, Fa; Schlich, R; Schaming, M; Montigny, R; Damasceno, D; Mattielli, N; Nicolaysen, Ke; Scoates, Js.
The gravity and bathymetric highs on the Kerguelen Plateau in the southern Indian Ocean between the Kerguelen Archipelago and Heard Island are seamounts formed of Miocene alkalic basalts similar to those found on the islands. Dredging during the Kerimis survey cruise recovered &gt;1 ton of mostly basaltic rocks. One of the dredges (D6) yielded a large volume of in situ alkalic picritic pillow basalts, the first picritic lavas recovered that are related to the Kerguelen plume. K-Ar and Ar-40-Ar-39 ages are between 18 and 21 Ma for all but one sample, and these ages are only slightly younger than the main phase of volcanism on the archipelago. The dredged lavas form three distinct groups based on chemical and isotopic compositions. Incompatible element...
Tipo: Text
Palavras-chave: Kerguelen; Trace elements; Isotopes; Mantle plume; Hot spot track; Picrites; Geochemistry; 1025 Geochemistry : Composition of the mantle; 1040 Geochemistry : Isotopic composition/chemistry; 1065 Geochemistry : Trace elements (3670).
Ano: 2002
URL: https://archimer.ifremer.fr/doc/00223/33407/31856.pdf

Origin of organic compounds in fluids from ultramafic-hosted hydrothermal vents of the Mid-Atlantic Ridge
Provedor de dados: 5
Autores: Konn, Cécile.
Natural gas, primarily methane (CH4), is produced in substantial amounts in ultramafic-hosted hydrothermal systems. These systems could also generate oil (heavier hydrocarbons) and the first building blocks of life (prebiotic molecules). In the presence of iron bearing minerals, serpentinisation reactions generate H2. Subsequently, CH4 could be synthesised by Fischer-Tropsch Type (FTT) reaction (4H2 + CO2 -&gt; CH4 + 2H2O) which is an abiotic process. This has lead to the idea of abiotic formation of larger organic molecules. Both thermodynamics and laboratory work support this idea, yet field data have been lacking. This study focuses on determining the organic content of fluids from ultramafic-hosted hydrothermal systems from the Mid-Atlantic Ridge (MAR)...
Tipo: Text
Palavras-chave: Origin of life; Geochemistry; Hydrothermal; Ultramafic; Organic compounds; Hydrocarbons; Serpentinisation; Origine de la vie; Géochimie; Systèmes hydrothermaux; Ultrabasique; Composés organiques; Hydrocarbures; Serpentinisation.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/these-6939.pdf

Tephra horizons identified in the western North Atlantic and Nordic Seas during the Last Glacial Period: Extending the marine tephra framework
Provedor de dados: 5
Autores: Rutledal, Sunniva; Berben, Sarah M.p.; Dokken, Trond M.; Van Der Bilt, Willem G.m.; Cederstrøm, Jan Magne; Jansen, Eystein.
Geochemically distinct volcanic ash (tephra) deposits are increasingly acknowledged as a key geochronological tool to synchronize independent paleoclimate archives. Recent advances in the detection of invisible (crypto) tephra have led to the ongoing establishment, development and integration of regional tephra lattices. These frameworks offer an overview of the spatial extent of geochemically characterized tephra from dated eruptions – a valuable tool for precise correlation of paleorecords within these areas. Here, we harness cryptotephra analysis to investigate the occurrence of two well-known tephra markers from the Last Glacial Period (i.e. FMAZ II-1 (26.7 ka b2k) and NAAZ II (II-RHY-1) (55.3 ka b2k)), in marine sediment cores from the Nordic,...
Tipo: Text
Palavras-chave: Tephrochronology; Cryptotephra Tephrostratigraphy; Tephra isochrons; FMAZ II; NAAZ II; Geochemistry; Paleoceanography; Marine sediment cores Quaternary; North Atlantic Ocean.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00614/72659/71665.pdf

The provenance of sediments in the Gulf of Lions, western Mediterranean Sea
Provedor de dados: 5
Autores: Revillon, Sidonie; Jouet, Gwenael; Bayon, Germain; Rabineau, Marina; Dennielou, Bernard; Hemond, Christophe; Berne, Serge.
In this study, we undertook a reconnaissance study of sediments provenance in the Gulf of Lions focusing over the last 16 ka. We used geochemical and isotopic tracers to determine the source of sediments and give insight into the weathering conditions prevailing. Sediments samples were selected both onshore and offshore from the western, eastern, and central part of the Gulf of Lions. We analyzed bulk sediments, coarse and fine silt, and clay fractions. Elemental and Nd isotope compositions appeared to differ from one grain size fraction to another one. These are interpreted in terms of zircon addition in the coarse silt fraction for the elemental concentrations and variable sources influences for the Nd isotope compositions. Our results indicate that...
Tipo: Text
Palavras-chave: Geochemistry; Provenance; Sediment; Weathering.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00043/15376/12734.pdf

Isolating coccoliths from sediment for geochemical analysis
Provedor de dados: 5
Autores: Halloran, Paul R.; Rust, Nigel; Rickaby, Rosalind E. M.
Trace element analysis of open-marine sedimentary carbonates provides a wealth of paleoclimate data. At present, the majority of this data is obtained from foraminifera tests. Complications regarding the variability of conditions experienced by foraminifera throughout test formation and the influence of diagenetic processes on sample chemistry limit the value of foraminifera samples in certain situations. Coccoliths, the calcium carbonate plates produced by coccolithophores, represent a second major pelagic open-marine carbonate source with the potential to provide a wide range of valuable trace element proxy data but which have, until now, been unavailable for analysis of many trace elements because of clay contamination. Here we describe a novel...
Tipo: Text
Palavras-chave: Coccolith; Coccolithophore; Clay; Sorting; Trace element; Geochemistry.
Ano: 2009
URL: https://archimer.ifremer.fr/doc/00220/33080/31542.pdf

Diffusion induced Li isotopic fractionation during the cooling of magmatic rocks: The case of pyroxene phenocrysts from nakhlite meteorites
Provedor de dados: 5
Autores: 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

Estudio geoquímico de los sedimentos en el Canal de Jambelí
Provedor de dados: 20
Autores: Jácome de Solórzano, M.; Llanos de Bonilla, L.
Se presenta las características geoquímicas del Canal de Jambelí en base al análisis de 41 muestras de sedimentos del fondo marino, obtenidas durante marzo y junio de 1986 (Fig.1). Se identifica la presencia de dos dominios de sedimentación, el uno de tipo fluvial y el otro marino; así mismo una posible tendencia de avance del sedimento fluvial sobre el sedimento marítimo. Se establece además que la concentración de los constituyentes orgánicos se encuentran dentro de rangos normales y guarda relación con la textura del sedimento.
Tipo: Journal Contribution
Palavras-chave: Geochemistry; Sediments; Geochemistry; Http://aims.fao.org/aos/agrovoc/c_24848.
Ano: 1987
URL: http://hdl.handle.net/1834/2131

Hydrologie, sédimentaire et géochimie de l'oued Tinja (Tunisie septentrionale
Provedor de dados: 20
Autores: Ben Gharali, A.; Ouakad, M.; Gueddari, M.
L'oued Tinja relie la garaet Ichkeul à la lagune de Bizerte laquelle communique avec la mer Méditerranée par un long goulet. Les eaux de cet oued dépendent à la fois des apports saisonniers des eaux marine et douce et présente de ce fait, des salinités très fluctuantes. L'important réseau hydrographique associé au plan d'eau de l'Ichkeul (avec un bassin versant très important d'environ 2080 km2) est sujet à de nombreux aménagements hydrauliques, notamment la construction de barrages de retenues d'eau douce. Ces derniers sont susceptibles de perturber les caractéristiques hydrologiques, sédimentologiques et géochimiques du système laguno-lacustre (lagune de Bizerte et garaet Ichkeul) et d'entamer par voie de conséquence sa diversité et sa richesse...
Tipo: Journal Contribution
Palavras-chave: Environmental impact; Geochemistry; Hydrology; Quality; Sediment analysis; Species diversity.
Ano: 2008
URL: http://hdl.handle.net/1834/4270

Evaluación geoquímica en la fase sedimentaria de ecosistemas costeros del Estado de Sonora, México
Provedor de dados: 20
Autores: Villalba, A.I.; Ortega Romero, P.; De la O Villanueva, M.
Se elaboró este trabajo en los cuerpos lagunares Guásimas, Algodones y Lobos y contribuir, de esta forma, al conocimiento geológico marino de los sistemas costeros del litoral de Sonora.
Tipo: Journal Contribution
Palavras-chave: Evaluation; Geochemistry; Sediments; Coastal lagoons; Evaluation; Geochemistry; Coastal lagoons; Http://aims.fao.org/aos/agrovoc/c_2736; Http://aims.fao.org/aos/agrovoc/c_24848; Http://aims.fao.org/aos/agrovoc/c_1697.
Ano: 1989
URL: http://hdl.handle.net/1834/2159

Características oceanográficas y geoquímicas del Golfo de Guayaquil durante noviembre de 1994
Provedor de dados: 20
Autores: Cuadra, T. de la; Chalén, X.; Pérez, P.; Macías, P.; Ortega, D.; Ormaza, F.
Las masas de agua encontradas a partir de las variables de estado, indican una contribución muy pobre de Agua Subtropical Superficial (ASTS), mientras que las mayores contribuciones fueron de Agua Tropical Superficial (ATS). Parámetros como la temperatura y la salinidad determinaron un calentamiento del océano, tanto a nivel superficial como subsuperficial, lo cual sería una consecuencia de los procesos de redistribución de calor del océano.Esta dinámica ocasionaría anomalías del orden de los 30 metros para el caso de la profundidad de la termoclima y 2°C para el caso de la TSM. En el plancton se registraron valores mayores a 5000 larvas de peces/10 m2. La menor cantidad (260 larvas/10 m2) se registró hacia el norte del Golfo, observándose al mismo tiempo...
Tipo: Journal Contribution
Palavras-chave: Oceanographic data; Geochemistry; Salinity data; Plankton; Organic matter; Plankton; Organic matter; Geochemistry; Http://aims.fao.org/aos/agrovoc/c_5950; Http://aims.fao.org/aos/agrovoc/c_5387; Http://aims.fao.org/aos/agrovoc/c_24848.
Ano: 1994
URL: http://hdl.handle.net/1834/3080

Hydrologie, sédimentologie et géochimie de l'oued tinja  (Tunisie septentrionale)
Provedor de dados: 20
Autores: Ben Garali, A.; Ouakad, M.; Gueddari, M.
L'oued Tinja relie la garaet Ichkeul à la lagune de Bizerte laquelle communique avec la mer Méditerranée par un long goulet. Les eaux de cet oued dépendent à la fois des apports saisonniers des eaux marine et douce et présente de ce fait, des salinités très fluctuantes. L'important réseau hydrographique associé au plan d'eau de l'Ichkeul (avec un bassin versant très important d'environ 2080 km2) est sujet à de nombreux aménagements hydrauliques, notamment la construction de barrages de retenues d'eau douce. Ces derniers sont susceptibles de perturber les caractéristiques hydrologiques, sédimentologiques et géochimiques du système laguno-lacustre (lagune de Bizerte et garaet Ichkeul) et d'entamer par voie de conséquence sa diversité et sa richesse...
Tipo: Journal Contribution
Palavras-chave: Marine sciences; Quality; Species diversity; Geochemistry; Environmental impact; Hydrology; Freshwater lagoons; Sediment analysis.
Ano: 2008
URL: http://hdl.handle.net/1834/4248

Iron oxides and quality of organic matter in sugarcane harvesting systems
Provedor de dados: 90
Autores: Barbieri,Diogo Mazza; Marques Júnior,José; Siqueira,Diego Silva; Teixeira,Daniel De Bortoli; Panosso,Alan Rodrigo; Pereira,Gener Tadeu; La Scala Junior,Newton.
Improvements in working conditions, sustainable production, and competitiveness have led to substantial changes in sugarcane harvesting systems. Such changes have altered a number of soil properties, including iron oxides and organic matter, as well as some chemical properties, such as the maximum P adsorption capacity of the soil. The aim of this study was to characterize the relationship between iron oxides and the quality of organic matter in sugarcane harvesting systems. For that purpose, two 1 ha plots in mechanically and manually harvested fields were used to obtain soil samples from the 0.00-0.25 m soil layer at 126 different points. The mineralogical, chemical, and physical results were subjected to descriptive statistical analyses, such as the...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Degree of humification; Geochemistry; Soil management; Sustainable agriculture.
Ano: 2014
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832014000400010

Background and Reference Values of Metals in Soils from Paraíba State, Brazil
Provedor de dados: 90
Autores: Almeida Júnior,Agenor Bezerra de; Nascimento,Clístenes Williams Araújo do; Biondi,Caroline Miranda; Souza,Adailson Pereira de; Barros,Felipe Martins do Rêgo.
ABSTRACT Soil contamination by heavy metals threatens ecosystems and human health. Environmental monitoring bodies need reference values for these contaminants to assess the impacts of anthropogenic activities on soil contamination. Quality reference values (QRVs) reflect the natural concentrations of heavy metals in soils without anthropic interference and must be regionally established. The aim of this study was to determine the natural concentrations and quality reference values for the metals Ag, Ba, Cd, Co, Cu, Cr, Mo, Ni, Pb, Sb and Zn in soils of Paraíba state, Brazil. Soil samples were collected from 94 locations across the state in areas of native vegetation or with minimal anthropic interference. The quality reference values (QRVs) were (mg...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Geochemistry; Soil pollution; Micronutrients; Trace elements.
Ano: 2016
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832016000100509

Late Holocene vegetation dynamics and lake geochemistry at Laguna Miranda, XI Region, Chile
Provedor de dados: 97
Autores: HABERLE,S. G.; SZEICZ,J. M.; BENNETT,K. D.
Palynological and geochemical analysis of late Holocene lake sediments and dendrochronological analysis of Pilgerodendron in a volcanically active region of southern Chile reveal the long-term impact of a series of tephra fall events and tectonic activity on lake sedimentation and local vegetation. An upper 0,75 m core overlaps with a 4,35 m long Livingstone piston core to give a 4,60 m long sediment record, extending back to 4800 yr BP. Geochemical data shows the shift from allogenic dominance to authigenic and biogenic dominance as waterlogged soils developed within the catchment. This is presumed to have occurred under the influence of continued addition of nutrients to the catchment from tephra deposition and the associated high sedimentation rates....
Tipo: Journal article
Palavras-chave: Hudson Volcano; Tephra; Pollen; Geochemistry; Dendrochronology.
Ano: 2000
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2000000400010

Stratigraphy of amethyst geode-bearing lavas and fault-block structures of the Entre Rios mining district, Paraná volcanic province, southern Brazil
Provedor de dados: 42
Autores: 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

Stonemeal of amazon soils with sediments from reservoirs: a case study of remineralization of the tucuruí degraded land for agroforest reclamation
Provedor de dados: 42
Autores: THEODORO,SUZI H.; LEONARDOS,OTHON H.; ROCHA,EDUARDO; MACEDO,IRIS; REGO,KLEYSSON G.
This study suggests the employment of accumulated sediments in the reservoir of Tucuruí (Pará /Brazil) to remineralize the surrounding degraded soils. The approach was based on the principles of stonemeal technology. It suggests that the soil can be rejuvenated by crushed rocks rich in macro and micronutrients. Removal of the sediments for agricultural use will bring benefits to family farmers and increase the life cycle of the reservoir and, therefore, energy generation. Geochemical data on retained sediments, soils and rocks in the area of influence of the reservoir were evaluated regarding nutrient transport mechanisms and soil-fertility potential. Results show that sediments from the reservoir contain nutrients levels at least one order of magnitude...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Geochemistry; Sediments; Reservoir; Agroforestry; Sustainable development.
Ano: 2013
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652013000100023

Petrography and mineral chemistry of carbonatites and mica-rich rocks from the Araxá complex (Alto Paranaíba Province, Brazil)
Provedor de dados: 42
Autores: 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

Geochemistry and δ11 B evolution of tourmaline from tourmalinite as a record of oceanic crust in the Tonian Ibaré ophiolite, southern Brasiliano Orogen
Provedor de dados: 42
Autores: ARENA,KARINE DA ROSA; HARTMANN,LÉO AFRANEO; LANA,CRISTIANO DE CARVALHO; QUEIROGA,GLÁUCIA NASCIMENTO; CASTRO,MARCO PAULO DE.
Abstract  The isotopic and geochemical evolution of tourmaline constrain the processes of paleo-oceanic lithosphere in ophiolites. The Brasiliano Orogen is a major structure of South America and requires characterization for the understanding of Gondwana supercontinent evolution. We made a pioneering investigation of tourmaline from a tourmalinite in the Ibaré ophiolite by integrating field work with chemical analyses of tourmaline by electron microprobe (EPMA) and δ11B determinations via laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS). Remarkably massive tourmalinite (&gt;90 vol.% tourmaline, some chlorite) enclosed in serpentinite has homogeneous dravite in chemical and isotopic composition (δ11B = +3.5 to +5.2‰). These results...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Boron isotopes; Geochemistry; Ibaré ophiolite; Tourmalinite; Southern Brasiliano Orogen.
Ano: 2020
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652020000100603

Holocene history of a lake filling and vegetation dynamics of the Serra Sul dos Carajás, southeast Amazonia
Provedor de dados: 42
Autores: 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

Geology, petrography and geochemistry of the A-type granites from the Morro Redondo Complex (PR-SC), southern Brazil, Graciosa Province
Provedor de dados: 42
Autores: VILALVA,FREDERICO C.J.; VLACH,SILVIO R.F.
The Morro Redondo Complex is one of the most important occurrences of the Graciosa A-type Province, southern Brazil. It consists of the Papanduva and Quiriri granitic plutons and a contemporaneous bimodal volcanic association. The Papanduva Pluton includes massive and deformed peralkaline alkali-feldspar granites with Na-Ca and Na-amphiboles and clinopyroxenes. The deformed types are the most evolved rocks in the province and carry rare ‘agpaitic’ minerals, some being described for the first time in granites from Brazil. The larger Quiriri Pluton comprises massive, slightly peraluminous, biotite syeno- and monzogranites with rare Ca-amphibole. Biotite compositions are relatively homogeneous, whereas sodic amphiboles and clinopyroxenes show increasing Na...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: A-type granites; Geochemistry; Petrography; Graciosa Province; Mineralogy; Morro Redondo Complex.
Ano: 2014
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652014000100085