Permo Triassic Maps of Africa

Permo-Triassic Palaeogeographic and Paleotectonic Maps of Africa

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

Kungurian 275Ma

Key Events/Points
•1. ‘European’ Hercynian tectonics are dying out but Morocco still in ‘Tardi-Variscan’ phase (Hoepffner at al, 2006) characterised by strike slip movements on faults and mild folding
•2. Mauritanides remain active till later in the Permian (Villeneuve, 2005) with radiometric dates from 360-250Ma. Consistent with tectonic activity in USA
•3. Reeh (2007) proposes a model by which North Africa is dominated at this time by WNW-ESE directed dextral shear fauts related to ‘Tardi-Variscan’ Activity. This could be used to explain the Djeffara Rift and the thick deep marine succession observed at this time in Sicily (Basilone et al 2016). Others (Guiraud et bal 2005, Stampfli eat al 2001) have suggested these rifts and this deep marine succession are indicative of a Permian ocean or area of highly extended crust related to the onset of the Neotethyan Ocean in the Middle East
•4. A NE-SW orientated shear system seems to divided the Gondwana plate (‘STASS’=Southern Trans African Shear System) , commencing in the Artinskian. Several pulses of ‘Karroo’ graben tectonics are documented,including one at this time (Macgregor 2018). Granath (2020) documents both dextral and sinistral movements, although the latter is dominant. This system appears to be part of wider shear tectonics affecting much of Gondwana at this time (Visser and Praekelt,, 1996). The trend likely continues between Somalia and Madagascar to the splitting of Iranian terranes from south of Oman. The extension to South America is less clear though a shear system affects the Parana Basin up until this time
•5. The Cape Fold Belt became active in latest Carboniferous though radiometric peaks are considerably younger than this (Linol and De Wit, 2016) . Model shown is related to compression of a backarc basin in northern Patagonia (Visser and Praekelt, 1996) . Activity in the CFB appears to have been contemporaneous with the Karoo transtensional phases along the STASS, commencing with the subsidence of the Karoo foredeep in the late Ghzelian (Catuneanu et al, 2005)
•6. The climate was cold at this time with the South Pole located close to the Falklands, following regional glaciation from 300-289 Ma (Catuneanu et al, 2005). Climate change was rapid during the Permian with all glaciers lost by the Sakmarian
•7. A widespread belt of coals occurs in the Artinskian and early Kungurian, peaking at paleolatitudes around 30-40 deg S

Induan 250 Ma

•1. Start of a new rift cycle commences with first rifting in Late Permian of Argana Valley, Morocco (Frizon et al, 2008)

•2. Rifting and deposition appear to terminate in Djeffara Basin, with depocentre moving northwards?. Thick late Permian with reefs in Tunisian portion of basin

•3. Rifting of Palymrides is Late Permian (Brew et al, 2001), consistent with a model of Neotethyan rifting younging eastwards. Late Triassic oceanic basalts outcropping in Cyprus (Bosch et al, 2007) suggests breakup followed in adjacent parts of Eastern Med . Paymyrides trends may continue into Levantine Basin, but timing is not consistent with apparent rifting in Tunisia or Sicily

•4.Kiri High of Cuvette Centrale active Late Permian to Early Triassic (Giresse, 2005), on this timing apparently more related to Cape Fold Belt than to Hercynian events

•5. Further less significant rifting event in southern Karoo basins but rifting now expanding northwards of Kenya to Ethiopia etc (Macgregor, 1996) where it is main rift phase

•6. Middle/Upper Sakamena Fm of Madagascar is doubtfully marine (Wescott and Diggens, 1997, 1998) Ammonite bearing strata in Late Permian in Majunga Basin. Marine inlet likely comes through rifts seen on seismic offshore Somalia

•7. Radiometric dates in Cape Fold Belt peak between 275 and 252Ma. Conglomeratic horizons in basal Triassic suggest deformation continues into Triassic (Linol and De Witt, 2016)

Carnian 230Ma

•1. Hercynian-Variscan topography assumed to largely worn down by this time. Rifting from Florida through to Tunisia – ‘Newark Rifts’ mapped after Frizon et al (2008), Ye et al 2017 and Le Roy and Pique 2001. Rifting commences over much of region in Carnian (though older than this in parts of Morocco)

•2. Triassic Basin of Algeria commences subsidence in Anisian (Turner and Sherif 2007), with deposition of the TAGI, though main rift phase is post-reservoir

•3. End of phase of rapid movement of Gondwana towards Equator and rapid climate change. Equator now over North Africa

•4. Rifting has largely ceased over ‘Karroo’ basins with only pulses of subsidence and rift fill by fluvial strata (Macgregor, 2016)

•5. Tectonic activity has also ceased in Cape Fold Belt and this is being worn down, with deposition of the ‘Beaufort’ fluvial clastics