{"refrec":{"BRefID":302299,"RR":"Niemi, T.M.; Ben-Avraham, Z.; Hartnady, C.J.H.; Reznikov, M. (2000). Post-Eocene seismic stratigraphy of the deep ocean basin adjacent to the southeast African continental margin: a record of geostrophic bottom current systems. Mar. Geol. 162(2-4): 237-258. https://dx.doi.org/10.1016/s0025-3227(99)00062-6","BEntID":294543,"PublicFlag":1,"CheckedFlag":0,"wosflag":1,"vabbflag":0,"RefStringPartII":". Mar. Geol. 162(2-4): 237-258. https://dx.doi.org/10.1016/s0025-3227(99)00062-6","DocTypID":8,"DocType":"Journal article","MarineFlag":0,"FreshFlag":0,"BrackishFlag":0,"TerrestrialFlag":0,"Authorstring":"Niemi, T.M.; Ben-Avraham, Z.; Hartnady, C.J.H.; Reznikov, M.","OrigTitleTranslFlag":0,"Authorstringtrunc":"Niemi, T.M. et al.","Englishabstract":"A high-resolution seismic-reflection survey of the Transkei Basin and Natal Valley permits the first recognition of three major reflectors that mark basin-wide unconformities across the continental rise and deep abyssal plain off the southeast African continental margin. Reflector O marks a change in acoustic reflectivity, coincident with a change in sedimentary bedforms from generally parallel bedding below to large-scale lenticular and clinoform shapes above. Reflector O probably marks the onset of cold, abyssal current circulation around the Eocene–Oligocene boundary. The overlying O sequence records deposition of a contourite drift (Oribi Drift) by northeast flowing abyssal currents at ∼4000 m water depths along the continental rise of the northeastern Agulhas Fracture Zone. This water depth is shallower than present-day Antarctic Bottom Water (AABW). The M reflector unconformity (possibly lower Middle Miocene) marks seafloor erosion in 4500 m water depth in the Transkei Basin and the cessation of drift construction along the continental rise. Above reflector M in the abyssal plain, a contourite drift (M-Drift) records deposition from an east-flowing bottom current in a location similar to, but slightly shallower than present-day AABW. The stagnation of bottom current activity in the northern Natal Valley and/or a rapid influx of sediment accumulation is marked by M sequence turbidite sediments (the Mzimkulu apron) deposited against and burying the Oribi Drift on the continental rise. Reworking of M sequence sediment along the continental rise to form low mounds (M4) and sediment waves in the northern Natal Valley indicate that a shallow, bottom current flowed at depths of 3800 to 3600 m. The coeval current-molding of the slope and abyssal plain indicates a two-layered structure of the bottom water may have commenced in the Miocene. Reflector P is the most pronounced unconformity in the deep abyssal plain, where it truncates M Sequence reflectors, and marks the base the Agulhas Drift which stands approximately 200 m above the surrounding seafloor. The P Sequence sedimentation is estimated to have begun in the Pliocene prior to or concurrent with an expansion of Southern and Northern polar ice-caps. Major slumping of the continental slope in the Natal Valley also began at this time, probably triggered by a combination of onland neotectonic activity and erosion of the base of the slope by vigorous bottom currents (possibly North Atlantic Deep Water, NADW).","AbstractOtherLang":null,"BibLvlCode":"AS","StandardTitle":"Post-Eocene seismic stratigraphy of the deep ocean basin adjacent to the southeast African continental margin: a record of geostrophic bottom current systems","OrigTitleLangCode":"en","OrigTitleLangCodeExtended":"eng","OrigTitleLangID":15,"DateLastModified":{"date":"2026-05-21 01:33:11.800035","timezone_type":1,"timezone":"+02:00"},"UserAccessRight":null,"UserAccID":null,"AuthorKeywords":"AABW; southeast Africa continental margin","OtherDescriptors":null,"Notes":null,"AnaPub":2000,"MonPub":null,"DateUpdate":"2018-10-22","DateCreate":"2018-10-22","SecASFANote":null,"ConfID":null,"PeerRev":1,"VlizCoreFlag":1,"WoScode":"WOS:000085933900003","VABBcode":null,"OpenAcc":0,"DOI":"10.1016/s0025-3227(99)00062-6"},"refs":null,"anarec":{"AnaID":302299,"PubliDate":2000,"Pagination":"237-258","XtraPublOfAnaID":null,"ISBN":null,"Volume":"162","Issue":"2-4","BRefMon":null,"BRefMonRR":null,"BRefXtra":null,"BRefXtraRR":null,"SerBRefID":43365,"SerRR":"Marine Geology. Elsevier: Amsterdam. ISSN 0025-3227; e-ISSN 1872-6151","StandardTitleSer":"Marine Geology","ISSN":"0025-3227","AbbrevSer":"Mar. Geol.","StandardTitleMon":null,"StartPage":237,"Pages":22,"ToPubliDate":null,"BRefBibLvlCode":"S","SerNotes":null},"monrec":null,"serrec":null,"relations":null,"relationsRev":null,"addrec":null,"othpubs":null,"ownerships":null,"authors":[{"AutName":"Niemi","Firstname":"Tina","Initials":"T.M.","Affiliation":null,"Discriminator":null,"CorporateFlag":0,"BEntID":294543,"AutID":347860,"OrderNr":1,"DegrID":null,"EditorFlag":0,"CorrespFlag":0,"IllustratorFlag":0,"ReviserFlag":0,"TranslatorFlag":0,"InsAcronym":null,"InsFSN":null,"ORCID":null,"PersID":null,"InsID":null},{"AutName":"Ben-Avraham","Firstname":"Zvi","Initials":"Z.","Affiliation":null,"Discriminator":null,"CorporateFlag":0,"BEntID":294543,"AutID":270817,"OrderNr":2,"DegrID":null,"EditorFlag":0,"CorrespFlag":0,"IllustratorFlag":0,"ReviserFlag":0,"TranslatorFlag":0,"InsAcronym":null,"InsFSN":null,"ORCID":null,"PersID":null,"InsID":null},{"AutName":"Hartnady","Firstname":"Chris","Initials":"C.J.H.","Affiliation":null,"Discriminator":null,"CorporateFlag":0,"BEntID":294543,"AutID":347861,"OrderNr":3,"DegrID":null,"EditorFlag":0,"CorrespFlag":0,"IllustratorFlag":0,"ReviserFlag":0,"TranslatorFlag":0,"InsAcronym":null,"InsFSN":null,"ORCID":null,"PersID":null,"InsID":null},{"AutName":"Reznikov","Firstname":"Margaret","Initials":"M.","Affiliation":null,"Discriminator":null,"CorporateFlag":0,"BEntID":294543,"AutID":347862,"OrderNr":4,"DegrID":null,"EditorFlag":0,"CorrespFlag":0,"IllustratorFlag":0,"ReviserFlag":0,"TranslatorFlag":0,"InsAcronym":null,"InsFSN":null,"ORCID":null,"PersID":null,"InsID":null}],"mapdetails":null,"datasets":[{"DasID":6043,"Acronym":null,"Citation":"Flanders Marine Institute; Renard Centre of Marine Geology - Ugent (2018). Global contourite distribution database, version 2. Available online at https://www.marineregions.org","StandardTitle":"Global contourite distribution database, version 2","RelationID":1,"DOI":null},{"DasID":6205,"Acronym":null,"Citation":"Flanders Marine Institute; Renard Centre of Marine Geology - Ugent (2019). Global contourite distribution database, version 3. Available online at https://www.marineregions.org","StandardTitle":"Global contourite distribution database, version 3","RelationID":1,"DOI":"10.14284/346"}],"monographs":null,"monparts":null,"serparts":null,"BEntOpen":null,"BEntPrivate":null,"availability":[{"BInstID":320203,"LibID":36,"BRefID":302299,"EmbargoDate":null,"FullEmbargoDate":null,"PhysMedID":16,"hasOCRd":1,"ShelfLocCode":"320203","RFID":null,"PaidValue":null,"Medium":"Server","Description":"Interne VLIZ documenten","Acronym":"VLIZ","Library":"Vlaams Instituut voor de Zee","DutchTerm":"Non-open access","URL":null,"ClassifID":228,"Classification":"Non-open access","ReqLink":1,"ClassifTypID":3,"URLLocation":"https://www.vliz.be/imisdocs/publications/","SubDir":1,"InternalReq":1,"LoggedInReq":1,"Disclaimer":"Disclaimer_VLIZ_Intern","DutchDisclaimer":"
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