Data/hora: 13/06/2024 04:01:05

Provedor de dados: 	5	
País: 	France	
Título: 	Geochemical features of site-840 from the tonga platform - a comparison with the other sites from leg-135 odp	
Autores: 	Vitali, F; Blanc, G; Larque, P; Samuel, J.	
Data: 	1994	
Ano: 	1994	
Resumo: 	The sedimentary sequence recovered at Site 840 ODP in the Tonga Platform is 597 m thick and ranges in age from Holocene to late Miocene. Here, from the 49 samples analysed, three classes of sediments can be identified, based on their proportion of biogenic carbonate and volcanogenic content. These three classes are comparable with those previously differentiated in the Lau Basin (Sites 834-839) and with some sediments from the Tonga Trench Margin (Site 841). In constrast with neighbouring Site 834-839 sediments from the Lau Basin, the Site 840 sediment composition appears to be exempt of hydrothermal pending material and seems to be characterized only by biogenic and terrigenous andesiticrhyolitic volcanic inputs. The alteration of volcanic material results principally in the replacement of the volcanic glass by smectite. This alteration is the major cause of the observed changes in the Ca, Mg, and K gradients in the interstitial waters. Diagenetic processes seem to be more pronounced in the deeper part of the hole, with the formation of abundant zeolite minerals.	
Tipo: 	Text	
Idioma: 	Inglês	
Identificador: 	http://archimer.ifremer.fr/doc/00099/21032/18658.pdf	
Editor: 	Gauthier-Villars	
Relação: 	http://archimer.ifremer.fr/doc/00099/21032/	
Formato: 	application/pdf	
Fonte: 	Oceanologica Acta (0399-1784) (Gauthier-Villars), 1994 , Vol. 17 , N. 5 , P. 517-533