Jurassic Paleotectonic and Paleogeographic Maps of Africa
Draft 1
an ongoing project using the plate model of Colin Reeves (www.reeves.nl)
Comments welcomed
Rhaetic/Hettangian 200Ma
Key Events/Points
•
•
•1. CAMP Plume volcanics
centred on 200Ma (Mchone,
2000: Pevye,
2015)
•2. Newark. Nova Scotia and Moroccan
Triassic rifts entering post-drift phase (Labails, 2010)
•3. It is unclear to how much of the
developing Central Atlantic margin was a volcanic margin. It is generally
thought that the extensive East Coast magnetic anomaly on the US margins ties
to SDRs (Davis, 2018). In the African margin SDRs are reported as present off
north Senegal (Petrosen,
2004) and Guinea Bissau/Demerara Plateau (Zinecker, 2020). Despite similar magnetic
anomalies to the ECM to the north of Senegal, no SDRS have been reported and
they seem to be absent off Morocco (Labails, 2010).
•4. Roberts et al report Morocco_Canaries as a
hyperextended margin with true oceanic
crust west of the Canaries and an abandoned hyperextended continental crust
basin in between the islands and Morocco
•5. Africa rapidly moving northwards and
climate warming
•6. Assumed topography associated with
CAMP Plume
Pleinsbachian 185Ma
•1. Centre point in time of Karoo volcanics
(Reeves. Peyve,
2015)
•2. SDRs in Mozambique assumed to be correlatable to
these (Senkans,
2019)
•3. Breakup of Central Atlantic, initially
slow (Pleinsbachian
pillow lava ages in Canaries) (Sahabi, 2001 places this in latest Sinemurian)
•4.Roughly assumed age of breakup of most
Eastern Mediterranean interpretations (Hinsbergen 2019,
Handy, 2010)
•Paleomag data
on Apulia shows potential for deviation from Africa at this time (Rosenbaum,
2004)
•Postdates
interpreted rifts in Levantine Basin (Schattner, 2007)
•Ocean
must predate Ligurian sea
opening in Bajocian-Bathonian otherwise Adria is compressed
•Low
heat flows in Ionian Sea suggest old ocean (Catalano, 2000)
•Postdates
Triassic rifts in much of NE Africa
•Though
questioned by rift history of e.g. Western Desert and deep marine environments
in Sicily/Malta not till Aalenian
(Catalano, 2013)
•5. Equator now in position from which it
will not drift much until Late Cret
Bajocian 170Ma
•1. Opening of Ligurian
Ocean, connected along Azores-Gibraltar transform to Central Med. Initiates a
long term sinistral
movement of Africa relative to Europe (Handy, 2010)
•2. Central Med spreading now extended to
Senegal. Evidence for break-up of this age from seismic correlations on Blake
Plateau (Sheridan, 1988)
•3. Eastern Med spreading possible
terminating (to allow Ligurian to
open), though this seems inconsistent with a major (second rift/?transtensional
phase in the Western Desert, Dolson, 1998)
•4.Trangressions of this age in e.g.
Tanzania suggest this is roughly the age of breakup of the Somali Basin/Ocean
(Macgregor, 2018). Oblique slip at this time – no Davie Transform at this time
(Phethean,
2016)
•5. Most datings in publications indicate volcanics/SDRs
still dominate in Mozambique (Senkans, 2019)
Kimmeridgian 155Ma
•1. Following a major concentration of
ocean opening enents
between the Pleinsbachian and
Bajocian, the Late Jurassic represents a generally more quiescent period,
dominated by accelerated spreading of these oceans (Central Atlantic, Ligurian,
Indian). Marked decrease overall in rift activity
•2. Sedimentation dominated in low paleolatitudes by
platform carbonates, indicative of low sediment supply and ?hinterland
topography
•3. High sea level with much of East
Africa transgressed and even evidence for marine strata in Cuvette Centrale,
again indicative of low topography
•4. Agulhas transform becomes active with
transverse rifts in Agulhas Basin (Mcmillan, 1997), between Falklands and Maurice
Ewing Bank, and southern Mozambique
(Salman, 1995) – how coeval are these?
•5. There’s good geometrical reasoning for Limpopia to
follow Antarctica fairly closely until about 138 Ma. At that time there is some upheaval that
creates a new midocean
ridge to the E of the Maurice Ewing Bank and south of Limpopia. This event also pushes Antarctica away from
Africa (Reeves
‘sidestep’),
temporarily deflecting it from its long-term trajectory (i.e. E-W. extension). This could
be the cause of rifting in southern Mozambique