Morphologyandarchitectureofthepresentcanyonandchannelsystemof the Zaire deep-sea fan N. Babonneau a, * , B. Savoye a , M. Cremer b , B. Klein c a IFREMER, Ge Âosciences Marines, Laboratoire Environnements Se Âdimentaires, BP70, 29280 Plouzane Â, France b De Âpartement de Ge Âologie et d'Oce Âanologie, Avenue des Faculte Âs, Universite  de Bordeaux I, 33000 Bordeaux, France c Total®naelf, 64018 Pau Cedex, France Received 18 June 2001; received in revised form 12 February 2002; accepted 19 February 2002 Abstract The Zaire deep-sea fan is one of the largest fans in the world still affected by turbidite sedimentation along a unique active meandering turbidite channel. This active channel is fed by turbidity currents, which are generated at the Zaire River mouth, and ¯ow via a deeply entrenched canyon across the shelf and the continental slope. BasedonadetailedstudyofthemorphologyandarchitectureofthepresentZaireCanyon/Channel,severalmainzonescanbede®nedthe canyon, the upper-fan valley, the upper and the lower channel-levee system leading into distal lobes). They are characterised by different behaviours in terms of erosion, transport and sedimentation within the canyon/channel. An important characteristic of the Zaire Canyon/Channel is the deep incision of the thalweg, well below the regional sea ¯oor along its wholepath.TheoriginofthisentrenchmentmaybelinkedtotheincisionoftheZaireCanyonbackacrosstheshelfduringthelastsea-level rise.ThisincisionofthecanyonhasallowedthecontinuityofturbiditeactivityduringtheHolocene,inmaintainingtheconnectionbetween the canyon head and the river mouth in contrast to most of other large deep-sea fans, which are generally inactive during highstands). The entrenchment of the Zaire Canyon/Channel limits the over¯ow of turbidity currents and the turbidite sedimentation over levees, and preventsavulsionalongtheupperpartoftheZaireChannel.Mostofthesedimenttransportedinturbiditycurrentsareprobablyleddownto the lower channel-levee system and the distal lobes. q 2002 Published by Elsevier Science Ltd. Keywords: Zaire deep-sea fan; Canyon; Channel-levee system; Meanders 1. Introduction The Zaire turbidite system constitutes a huge mud-rich deep-sea fan covering a large part of the Congo, Zaire and Angola margin Fig. 1). This system is fed by a unique canyon, which extends across the continental shelf and directly connects with the Zaire River estuary. Because of this connection, the Zaire turbidite system has remained active throughout the Holocene to the present-day. This current activity has been evidenced by submarine-cable breaks near the canyon Heezen, Menzies, Scneider, Ewing, & Granelli, 1964), which mainly occurred during Zaire River ¯oods. Prior to recent geological and geophysical data acquisi- tion during the ZAIANGO cruises, knowledge of the Zaire turbidite system was limited to the upper-fan, which was surveyedbytheGUINESScruisesDroz,Rigaut,Cochonat, & Tofani, 1996). The recent extension of the exploration of the Angola petroleum province into abyssal depths has led oilcompaniestoimprovetheirunderstandingofsedimenta- tion and transport processes, sedimentary architecture and facies associations, in order to develop more accurate reservoir models. The ZAIANGO project was developed by IFREMER and TotalFinaElf to study these aspects of the Zaire system and the adjacent Congo±Angola margin Savoye et al., 2000). Several cruises have been conducted since 1998. Data collected include multibeam bathymetry, acoustic imagery, high-resolution seismic pro®les, 3.5 kHz acousticpro®les,andpistoncoresFigs.3and4).Thiswide- ranging data set covers most of the Zaire deep-sea fan system. The main results of the ZAIANGO 1 and 2 cruises concerning the Zaire turbidite system are reported by Savoyeetal.2000).Theobjectiveofthispaperistopresent a more detailed study of the present Zaire turbidite system, based on the analysis of the bathymetric and seismic data provided by ZAIANGO. After a brief presentation of the geological setting of the margin, the Zaire River and the Marine and Petroleum Geology 19 2002) 445±467 0264-8172/02/$ - see front matter q 2002 Published by Elsevier Science Ltd. PII:S0264-817202)00009-0 www.elsevier.com/locate/marpetgeo * Correspondingauthor.Tel.: 133-2-9822-4819;fax: 133-2-9822-4570. E-mail address: nbabonne@ifremer.fr N. Babonneau).