Cretaceous Maps of Africa

CRETACEOUS PALEOTECTONIC AND PALEOGEOGRAPHIC MAPS OF AFRICA

DRAFT 2 FEB 22
An ongoing project using the plate model of Colin Reeves (www.reeves.nl)
Comments welcomed

Late Valanginian-Early Hauterivian 135Ma

Key Events/Points
•

•1 Plate seemingly under NE-SW tension throughout with many NW-SE rifts initiated

•2.. Expansion of CARS system westwards from Blue Nile Basin to incorporate Muglad etc (note well before Atlantic spreading), Genik 1993, McHargue, 1992)

•3. Transtensional basin formation also propagating west from Marajo Basin in Brazil (Costa, 2002, Ye, 2017) Also initiation of e.g. Araripe (Batista, 2017) and Potiguar Basins (Milani, 2007)

•4. First mild rift phase(Afro-Brazilian depression) in Reconcavo-Gabon area but not connected to southern South Atlantic (Chaboureau, 2012)

•5. Agulhas transform now pulling open southern extreme of South Atlantic. First oceanic crust S of Orange Basin (Macdonald, 2013; Franke, 2013)

•6. Parana-Etendeka volcanics peak in Hauterivian and seemingly pass into SDRs along Namibia and Uruguay margins (Macdonald, 2013; Franke, 2013) though some recent dates extend into Valanginian

•7. Start of weak Eo-Alpine compression on northern margin of Adria (Handy, 2010)

•8. Third and final phase of rifting of Western Desert following period of uplift and of volcanism in Israel (Dolson, 2014)

Barremian 130Ma

•1. AFTA data indicates Reguibat and Meseta rising and eroding (Bertotti, 2019) : carbonates changing to thick clastic succession in S Mauritania at this time (Kosmos presentations)

•2. End of spreading of Ligurian Ocean with initiation of subduction below Alkapeca/Iberia (Handy, 2010)

•3. Southern Sirt rifts (E-W trending) active (Hallett, 2016). Speculation that NW-SE branches may be becoming active (no data at depth)

•4. Marajo Basin active as pull-apart connected to transform likely connected to Ghana (Costa, 2002, Ye, 2017)

•5. Dextral transforms in Brazil/Cameroon according to Popoff (1998) . Some form northern terminations of S Atlantic rifts. Benue Trough faults reported however as sinistral suggesting that intervening block active as separate platelet

•6. Peak of rifting across South Atlantic Basins. Passing into sag sequences in Late Barremian (Chaboureau, 2012)

•7. End of SDRS in Namibia. Breakup of northern Namibia possibly termining at Mwembishi FZ extension (Franke, 2013)

Aptian 118Ma

•Period of plate reorganisation and major tectonic activity across nearly all areas of the African plate

•1. Major shift westwards and peak in Eo-Alpine orogeny on northern rim of Adria. Bay of Biscay rotating Iberia against NW Africa with subduction of Ligurian Ocean (Handy, 2010)

•2. ‘Austrian’ event of Late Aptian. Dextral faulting and transpression on old lineaments. Widepread uplift (shown as topography) and deep erosion surface over Libya as far east as Cyrenaica (Boote, 1998, Coward, 2003)

•3. Peak rifting in Sirt Basins, including Gulf of Sirt (Boote, 1998)

•4. Sirt rifts parallel Malta and to some extent Apulia escarpments. A number of authors suggest rifting prior to some slow (?re?) opening of the Ionian Sea (Jagger, 2018, Handy, 2010)

•5. Niger rifts now spreading northwards (Genik, 1992, sections). Start of main rift phase with close correlation to events in the Sirt Basin (Blaisse, 2019)

•6. Deep transtensional basins and lakes form and expand on Equatorial margins of Brazil and Africa (Teasdale, 2019, Antobreh, 2009, Ye, 2017. In most basins, Aptian is thought to be oldest sediments. Probably final connection of system through to CARS

•7. Salt over most South Atlantic basins from 118-114 Ma (Chaboureau, 2012). Above possible break-up unconformity at 122Ma . Hatching shows lithology above and below this unconformity, i.e. Late and Early Aptian. Was salt coeval with spreading ridge?

•8. Madagascar stops going southwards quite soon after M0. That makes it about 125 Ma on the IUGS2020 chart, though 118 Ma seems to have worked its way into folklore over many decades. The new Elsevier chart, however, has this event (base Aptian) suddenly at 121 Ma. Somali Ocean spreading now terminated

•9. First period of uplift of South African plateau, concentrated in south (Baby, 2018)

Late Albian 102Ma

•1. Northern part of South Atlantic (northern Gabon northwards) breaks up in Early Albian . SDRs in northern Gabon and Sergipe Basin (Fullarton, 2019)

•2. Arid climate at this time, so Congo not a major sediment deliverer. Pinda Sst of Cabinda and fan interpreted on seismic is first generation of Congo river (Anka, 2010, 2014)

•3. Anza rifting Growth of rift shoulders and uplift on Tanzanian Craton feed first major fans on Tanzanian margin. (Foster, 1992, Noble, 1997)

•4. Rivers feeding fans in Bradasdorp Basin (Brulpadda discovery : ponded vs Diaz transpressional arch)

•5. Two ‘break-up’ unconformities are recorded on the Eq Margin. – late mid Albian, representing first local formation of oceanic crust and 100Ma, representing full separation of plates (Antobreh, 2009, Dailly, 2012)

•6. Expansion of Orange river and start of prograding (Jungslager, 1999)

Santonian 86Ma

•1. Senegal and S Mauritania rivers seem to become inactive. Late K input is coming in from Reguibat in N. Mauritania. Major unconformity offshore Senegal

•2. High sea level throughout Late K mapped by Bonne, 2014. Marine sediments cover Palaeozoic basins of Libya and Algeria as well as Iullemeden Basin of Mali

•3. Second (mild ) rift phase in Sudan (Mchargue, 1992) (contrasts with sag tectonics in Niger)

•4. Jesomma Fm. clastics input to Somaliland and Ethiopia indicate a local uplift (Ali, 2019)

•5. Rivers on Eq Margin though to be maturing up the interval (Macgregor, 2003). Major system in particular develops as Abeokuta delta on Benin-Nigeria border

•6. Mild reactivation of rifts in Late Cretaceous north Africa such as Gabes and Sabratah Basins. Likely transtensional (Reeh, 2015, Mriheel, 2015). It is probably unlikely such mild movements are capable of opening the Sirt Basin as suggested by Anketell, (1996)

Maastrichtian-Danian 65Ma

•Relatively quiescent period

•1. India completes its split from the Seychelles and is rapidly migrating to NW, possibly still putting NE-SW stress on northern Africa

•2. Extension is now dying out across the CARS with all basins in a post-rift phase prior to Palaeogene reactivations (Genik, 1993, Mchargue (1992). The Niger rifts undergo a period of uplift and erosion

•3. Abeyance of Pyrenean events in Atlas prior to main Atlassic phase in Eocene (Handy, 2010)

•4.Reactivation of Syrian Arc inversions in Egypt (Bevan, 2012) (but not apparently in Benue Trough, although there is some disagreement between authors, Whiteman, 1982)

•5. Due to uplift in Niger, periodic marine inlets are pushed westwards to the Taoudenni and Iullemeden basin (Bonne, 2014)