Sabiia Seb
PortuguêsEspañolEnglish
Embrapa
        Busca avançada

Botão Atualizar


Botão Atualizar

Ordenar por: RelevânciaAutorTítuloAnoImprime registros no formato resumido
Registros recuperados: 6
Primeira ... 1 ... Última
Imagem não selecionada

Imprime registro no formato completo
Age, geochemical characteristics and petrogenesis of Cenozoic intraplate alkaline volcanic rocks in the Bafang region, West Cameroon ArchiMer
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
Imagem não selecionada

Imprime registro no formato completo
LiDAR offshore structural mapping and U/Pb zircon/monazite dating of Variscan strain in the Leon metamorphic domain, NW Brittany ArchiMer
Le Gall, Bernard; Authemayou, Christine; Ehrhold, Axel; Paquette, Jean-louis; Bussien, Denise; Chazot, Gilles; Aouizerat, Arthur; Pastol, Yves.
An exceptional structural picture of the immerged Variscan basement, offshore the Leon metamorphic domain, is supplied by high-resolution LiDAR and echosounder data recorded in the Molene archipelago, western Brittany (France). Various types of fabrics are identified and, from in situ rock sample analyses further combined with field structural data, are interpreted on a lineament trajectory map as the trace of magmatic and tectonic structures. Our onshore/offshore study leads us to propose a two-phase kinematic model that emphasizes the role of a strike-slip duplex in an EW-trending relay zone linking the North Armorican and Pierres Noires ductile shear zones (NASZ, PNSZ). Dextral shearing occurred within a transtensional setting, synchronously with...
Tipo: Text Palavras-chave: Armorican massif; Leon metamorphic domain; Offshore structural mapping; LiDAR records; Dextral ductile shearing; U/Pb zircon/monazite dating.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00194/30490/28895.pdf
Imagem não selecionada

Imprime registro no formato completo
Rainfall chemistry: long range transport versus below cloud scavenging. A two-year study at an inland station (Opme, France) ArchiMer
Bertrand, Guillaume; Celle-jeanton, Helene; Laj, Paolo; Rangognio, Jerome; Chazot, Gilles.
The present study investigates the chemical composition of wet atmospheric precipitation samples on a daily and an intra-event timescales in Opme, an experimental meteorological station located near Clermont-Ferrand, France. The samples have been collected from November 2005 to October 2007. A total of 217 rainwater samples, integrated for 24 h, were collected and analyzed for pH, conductivity, Na+, K+, Mg2+, NH4 (+) , Ca2+, Cl-, NO (3) (-) , SO (4) (2-) , PO (4) (3-) and HCO3 (-) . The composition of the rainwater collected appeared to be controlled by the following potential sources: neutralisation process (association among calcium, ammonium with nitrate and sulphate), marine and terrestrial sources. In order to determine the role of long-range...
Tipo: Text Palavras-chave: France; Chemistry; Air mass back trajectories; Sequential sampling; Major ions; Rainwater.
Ano: 2008 URL: http://archimer.ifremer.fr/doc/2008/publication-6390.pdf
Imagem não selecionada

Imprime registro no formato completo
Temporal magma source changes at Gaua volcano, Vanuatu island arc ArchiMer
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
Imagem não selecionada

Imprime registro no formato completo
Temporal source evolution and crustal contamination at Lopevi Volcano, Vanuatu Island Arc ArchiMer
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
Imagem não selecionada

Imprime registro no formato completo
Volcanic and hydrothermal processes in submarine calderas: the Kulo Lasi example (SW Pacific) ArchiMer
Fouquet, Yves; Pelleter, Ewan; Konn, Cecile; Chazot, Gilles; Dupre, Stephanie; Alix, Anne-sophie; Cheron, Sandrine; Donval, Jean-pierre; Guyader, Vivien; Etoubleau, Joel; Charlou, Jean-luc; Labanieh, Shasa; Scalabrin, Carla.
The study area is located at the transition between the northern end of the Tonga Trench and the North Fiji fracture zone, where tectonic movements are reputed to be the fastest in the world. To the southeast of Futuna Island, a broad area of volcanism occurs within a region characterized by a change in the tectonic fabric between a NE-SW oriented volcanic graben and the N-S oriented Alofi ridge. In 2010, the active volcano Kulo Lasi, which represents the most recent volcanic episode in the Futuna area, was discovered in the center of this extensive volcanic zone. Kulo Lasi is a 20 km diameter shield volcano that rises 400 m above the seafloor. It is composed of basaltic to trachy-andesitic lava with no obvious geochemical affinity with the Tonga...
Tipo: Text Palavras-chave: Subaqueous volcanism; Hydrothermal activity; Kulo Lasi caldera; Sulfides; SW Pacific.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00445/55633/57279.pdf
Registros recuperados: 6
Primeira ... 1 ... Última
 

Empresa Brasileira de Pesquisa Agropecuária - Embrapa
Todos os direitos reservados, conforme Lei n° 9.610
Política de Privacidade
Área restrita

Embrapa
Parque Estação Biológica - PqEB s/n°
Brasília, DF - Brasil - CEP 70770-901
Fone: (61) 3448-4433 - Fax: (61) 3448-4890 / 3448-4891 SAC: https://www.embrapa.br/fale-conosco

Valid HTML 4.01 Transitional