THE MEDITERRANEAN LOWER CRETACEOUS

Fig. 42. Palaeogeographic sketch-map of the South Atlantic during the Late Aptian (after
W i e d m a n n, 1982). Designations as in Fig. 40
Region this movement was predominantly convergent, and in the Eastern Mediterranean
Region — divergent (Dewey et al., 1973).
2.3. Opening of the Atlantic Ocean
Various authors have emphasized the close connection existing between the evolution
of the Tethys (including the Mediterranean Region) and the opening of the Atlantic
Ocean.
The evolution of the Atlantic Ocean comprises the following main stages:
(1) early riftogenesis accompanied by red sediments and alkaline volcanites; (2) evaporites;
(3) black shales; (4) first deltaic sediments; (5) carbonate platforms;
(6) intensive depression of the continental margins, which is well demonstrated in
the correlation of the sections from Morocco and the Iberian Peninsula with the
boreholes in the continental margin (Chapter III); canyons, thick turbidites, athols
and condensations in the upper part of the slope and or in the shelf were formed
during this stage; (7) expansion of the pelagic facies and decrease of the facial variety;
(8) emergence of the modern system of oceanic currents (D i e t z, H о 1 d e n,
1970; G r a с i a n s к y et al., 1979; Von Rad et al., 1982).
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