THE MEDITERRANEAN LOWER CRETACEOUS

Indeed, the facts which this researcher referred to did not prove to be accurate. According
to more recent data, in a regional plan, the coastal part of Bulgaria began
to rise after the Barremian and the basin gradually retreated to the west (H иколов,
1969b).
Comparison with other areas in the Mediterranean Region produced surprising
results which suggest the first impulse of tectonic activation in a number of zones
as early as the beginning of the Barremian. Strong faulting in several belts and
ingression of sea waters into grabens took place in the Iberian Peninsula. Orogenic
movement was manifested in the Pyrenees, which is responsible for the discordant
position of the Barremian sediments over a varied basement. A second orogenesis
appeared during the Gargasian, followed later by Middle and Late Albian orogenesis.
The post-Aptian folding is particularly strong in Eastern Corbier, which lasted
in some places after the Late Albian and before the Cenomanian (Durand Delg
a, 1965a).
Intensive folding occurred in the Central and Eastern Fore-Balkan after the
Early Aptian, causing regression of the basin to the north-northwest, and transgressée
and discordant position of the Upper Cretaceous over the Lower Cretaceous
rocks.
Analogous and synchronous (Aptian-Aibian) movements existed in the Caucasus.
The basic orogenic manifestations in the Mediterranean Region during the Early
Cretaceous will be discussed briefly below.
In North Africa the Early Cretaceous movements are found in several regions,
where they have clear and considerable manifestations. The earliest movements
established for the dawn of the Cretaceous Period are manifested in this area (the
zone of the Moroccan Atlas and the Cabiles). They arc as a refrain to the Early Kimmerian
movements in the middle of the Berriasian. These movements are characterized
by two types of phenomena: folding and magmatism. Folding causes regression,
hiatuses and discordance. Magmatism is manifested in the Moroccan
Atlas (Demnate — Beni-Mellal) after the folding and it is represented by intrusions
and effusions of basic to alkali rocks of Early Cretaceous (mainly basalts and gabbro)
(M i с h a г d, 1976).
In the Pyrenees the Early Cretaceous tectonics is well manifested through several
considerable activations which have left defining characteristics in the structure
of the entire mountain range. There exist different opinions about the character
of these movements: (1) according to some authors, these are mainly vertical
movements resulting from intensive faulting; (2) according to other sources, these
are tectonic movements under conditions of shrinking with appearance of considerable
horizontal displacements. The following points are indisputable:
1. There was unusual magmatic activation with formation of basic and ultrabasic
rocks in the Northern Pyrenees during the Early Cretaceous, which is related
to pre-Aptian tectonics.
2. Several clear regional discordances are established, connected with orogenesis
before the Barremian, before the Gargasian, before the Middle Albian and before
the Late Albian (Peybernes, 1976).
3. The most considerable folding occurred before the Cenomanian, when probably
the Lower Cretaceous sediments were slightly metamorphosed.
As it was noted, traces of clear Early Cretaceous folding were observed in Corbier
as well.
In Sardinia, Chabrier (1970) has found folding after the Early Cretaceous,
as a resuit of which basal conglomerates of the Upper Cretaceous lie transgressively
and discordantly.
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