| In this work, the main evidence and conclusions regarding the geological links between the basins of South American margin (Espirito Santos basin, Pelotas basin & Colorado basin) with the conjugate margin of Western African (Kwanza basin, Walvis basin & Orange basin) Many research works have been done in both margins of South Atlantic and Western African like sedimentation history and tectonic evolution. However, there are some cognition needs to be unified, and some geologic problems need to be further researched, such as the deposition of salt, extension of the basin, and the sedimentation history along the comparative basins.These basins were formed during the breakup of Gondwana, while the South Atlantic Ocean started to open during the Late Cretaceous at ca.131.7Ma, the sedimentation history between the Late Jurassic and present are broadly similar on both margins, where these basins are filled with the Cretaceous, Tertiary and the Quaternary sediments. However, the sediment of the Late Jurassic only deposit at Colorado basin in South American margin and at Kwanza basin and Orange basin in Western African margin. Sedimentation proceeded from the deposition of continental pre- and syn-rift facies, through syn-rift lacustrine, the turbiditic and transgressive shales, to shallow marine carbonates and evaporitic units before the deposition of a post rift marine transgressive and regressive sequence.During the opening of the South Atlantic Ocean there were some major events (i.e, the Parana & Etendeka volcanic plume, salt deposition before the opening of South Atlantic), these events at these two margins could be well matched. Tectonically, South Atlantic Ocean are divided into four major segments from South to North:the Falkland segment, the South segment, the Central segment and the Equatorial segment. South Atlantic Ocean contains two kinds of passive margins which are the thick crust volcanic margin and the thin-crust non-volcanic margin. The volcanic passive margins contain the Large Igneous Province (LIPs).The Florianopolis Fracture zone (South segment) which characterize the Seaward dipping reflectors (SDRs), and the volcanic distributed along the South Atlantic in the area with length of hundreds of km and width of over15km. The basins developed in the southern margin recorded the LIPs and SDRs. The most parts of the two margins are built on the block faulted continental crust (what does this mean) marked by the hinge zones, which are parallel along the coast or sub parallel to the ancient orogenic belts. While the strata deposited on both margins during the rifting are similar, the Evaporite sequences are formed in central segment on both margins. Resulted in several kilometers of mudstone and sandstone, alluvial and marine shelf origins were deposited in both margins. During the Cenozoic, the sedimentation rates are increased and the sediments in the study area are characterized by intercalated (marine clay, chalk, mudstone) and volcanic beds.The continental extension between West Africa and Brazil was directly or indirectly responsible in the development within the pre-salt sag basin, and also for the development of evaporates at the central segment in the South Atlantic Ocean which is important in the petroleum researches. The initial halite and anhydrite deposition occurred in the Espirito Santos of North East Brazil during ca.124.8 Ma, closely followed by the deposition within the Kwanza basin.All these evidence strongly supports initial rifting in the South Atlantic, after the time when separation of Brazil and Africa started. The initial phase of the East-west extension in South Atlantic rift basins occurred from ca.140Ma of earliest Cretaceous to ca.127Ma at Hauterivian. The second phase started from ca.126Ma of late Hauterivian ca.121Ma of earliest Aptian is characterized by the rapid lithospheric weakening. The last phase was started from ca.120 Ma with a breakup of the South Atlantic Ocean basins. |
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