Geological constraints on the evolution of the Angolan margin based on reflection and refraction seismic data (ZaïAngo project)
|Author(s)||Moulin Maryline1, Aslanian Daniel1, Olivet Jean-Louis1, Contrucci Isabelle1, Matias Luis2, Geli Louis1, Klingelhoefer Frauke1, Nouze Herve1, Rehault Jean Pierre3, Unternehr Patrick4|
|Affiliation(s)||1 : IFREMER, Ctr Brest, DRO Geosci Marines, F-29280 Plouzane, France.
2 : Univ Lisbon, Ctr Geofis, P-1269102 Lisbon, Portugal.
3 : Univ Bretagne Occidentale, Inst Univ Europeen Mer, Lab Domaines Ocean, F-29280 Plouzane, France.
4 : Total Explorat Prod Geosci Projets Nouveaux Exper, F-92078 Paris, France.
|Source||Geophysical Journal International (0956-540X) (Blackwell Publishing), 2005-09 , Vol. 162 , N. 3 , P. 793-810|
|WOS© Times Cited||140|
|Keyword(s)||Deep seismic reflection and refraction, Sub salt imaging, Transitional domain, Crustal structure, Non volcanic passive continental margin|
|Abstract||Deep penetration multichannel reflection and Ocean Bottom Seismometer wide-angle seismic data from the CongoAngola margin were collected in 2000 during the ZaïAngo cruise. These data help constrain the deep structure of the continental margin, the geometry of the pre-salt sediment layers and the geometry of the Aptian salt layer. Dating the deposition of the salt relative to the chronology of the margin formation is an issue of fundamental importance for reconstructing the evolution of the margin and for the understanding of the crustal thinning processes. The data show that the crust thins abruptly, from a 3040 km thickness to less than 10 km, over a lateral distance of less than 50 km. The transitional domain is a 180-km-wide basin. The pre-salt sediment layering within this basin is parallel to the base of the salt and hardly affected by tectonic deformation. In addition, the presence of a continuous salt cover, from the continental platform down to the presumed oceanic boundary, provides indications on the conditions of salt deposition that constrain the geometry of the margin at that time. These crucial observations imply shallow deposition environments during the rifting and suggest that vertical motions prevailedcompared to horizontal motionsduring the formation of the basin.|