Home Itens selecionados Provedores de dados OAI Créditos Sobre Ajuda

			Busca avançada
	Provedor de dados ArchiMer (2) Autor Villanueva, J (2) Bertrand, P (1) Boelaert, A (1) Calvo, E (1) Disnar, Jr (1) Giraud, X (1) Grimalt, Jo (1) Huc, Ay (1) Labeyrie, L (1) Lallier-verges, E (1) Massias, D (1) Pedersen, Tf (1) Pelejero, C (1) Pierre, C (1) Schneider, R (1) Shimmield, G (1) Tribovillard, N (1) Venec-peyre, Mt (1) Mais... Palavra-chave And modeling Marine organic chemistry Organic and biogenic geochemistry (1) Biogeochemical cycles (1) Coastal upwelling (1) Deep-sea sediments (1) Petroleum source rocks (1) Processes (1) Quaternary climate (1) Southwestern African Margin (1) Mais... Tipo do documento Text (2) Ano 2003 (1) 2001 (1) País France (2) Idioma Inglês (2)		Ordenar por:  Relevância Autor Título Ano Registros recuperados: 2 Primeira ... 1 ... Última A latitudinal productivity band in the central North Atlantic over the last 270 kyr: An alkenone perspective ArchiMer Villanueva, J; Calvo, E; Pelejero, C; Grimalt, Jo; Boelaert, A; Labeyrie, L. Productivity changes in the central North Atlantic Ocean have been traced by means of the total C-37 alkenone contents along two sediment cores located at 43 degreesN and 37 degreesN. Both alkenone signals revealed the occurrence of discrete productivity events every 23 kyr. Spectral analyses highlight the presence of a dominant 23-kyr periodicity in the alkenone signal, which is highly coherent to the precession index. However, a close comparison revealed small but relevant differences in the timing of several of the productivity events recorded at both locations. These asynchronies suggest that the alkenone maxima do not necessarily reflect a general increase of productivity over the North Atlantic. We propose that the events are related to a latitudinal... Tipo: Text Palavras-chave: Biogeochemical cycles; Processes; And modeling Marine organic chemistry Organic and biogenic geochemistry. Ano: 2001 URL: https://archimer.ifremer.fr/doc/00221/33192/31790.pdf Organic-rich sediments in ventilated deep-sea environments: Relationship to climate, sea level, and trophic changes ArchiMer Bertrand, P; Pedersen, Tf; Schneider, R; Shimmield, G; Lallier-verges, E; Disnar, Jr; Massias, D; Villanueva, J; Tribovillard, N; Huc, Ay; Giraud, X; Pierre, C; Venec-peyre, Mt. Sediments on the Namibian Margin in the SE Atlantic between water depths of similar to1000 and similar to3600 m are highly enriched in hydrocarbon-prone organic matter. Such sedimentation has occurred for more than 2 million years and is geographically distributed over hundreds of kilometers along the margin, so that the sediments of this region contain a huge concentrated stock of organic carbon. It is shown here that most of the variability in organic content is due to relative dilution by buried carbonates. This reflects both export productivity and diagenetic dissolution, not differences in either water column or bottom water anoxia and related enhanced preservation of organic matter. These observations offer a new mechanism for the formation of... Tipo: Text Palavras-chave: Petroleum source rocks; Coastal upwelling; Deep-sea sediments; Quaternary climate; Southwestern African Margin. Ano: 2003 URL: https://archimer.ifremer.fr/doc/00224/33553/31977.pdf Registros recuperados: 2 Primeira ... 1 ... Última