THE MEDITERRANEAN LOWER CRETACEOUS

(Late Jurassic, Kimmeridgian) — the opening of the Atlantic is already considerable
in the northern and central parts; Tethys 5 Atlantic 3 (Early Cretaceous,
Hauterivian; —• South America was completely separated from Africa. This is
a particularly important stage in the evolution of the two areas.
During this stage (ifau : ivian-Barremian) there was activation of the fault
to the north of the Jberian I laiform. which passes to the north of Corsica and Sardinia,
and with which the Early Cretaceous ophiolites in the Alps (Piémont zone
and Dauphine) and in the Apennines are connected. At the same time the most widespread
sediments around this fault arc of the Maiolica type, being traced from
the Northwest Atlantic, through the Southern Alps, the Lombardia zone and the
Central Apennines to the Ionic zone in Western Greece (Bernoulli, 1972).
The obduction of the Othrys ophiolites from the Vardar zone in the Pelagonian
Massif tcok place during the Barremian (Dewey et a!., 1973; R i с о u,
M a r с о u x, 1980). Tethys 6. Atlantic 4 (Aptian-Aibian) coincides with considerable
activation in the Mediterranean Region (Fig. 44). The Atlantic Ocean
was already considerably opened. At the beginning of the Aptian the rate of
spreading and of the increase of the plates was about three times greater compared
with the initial stage, and this rate was preserved until the middle of the Late
Cretaceous (80 million years). Some authors associate the widespread Aptian transgression
with this increasing rate. A number of subduction zones were outlined in
the Mediterranean Region during this stase: Eastern Alps, Carpathians and Eastern
Serbia (G e y s s a n С 1980; D% w e y "et al., 1973; G r u b i c, 1974). The last
stage, i. e. Tethys 7'Atlantic 5, ended 80 million years ago (Santonian).
A general result of the gradual opening of the Atlantic Ocean, which is particularly
well manifested during the Early Cretaceous, is the progressive reduction
of the Tethys in the Mediterranean Region.
204
big. 44. The Mediterranean Region at the end of the Early Cretaceous (110-100 m.y.)
(after Dewey cl al.. 1973, Gcol. Soe. Ameiic.i Bull., 84, 3137-3180)
1 — subduction /ones; 2 -• ocean crust; J — transform faults; '/ — other faults; J — direction of
the plate movements