THE MEDITERRANEAN LOWER CRETACEOUS

Tn the same area, in the Nantebelte Group (Sulens klippe), С h a г о 1 1 a i s
et al. (1981) have found the following succession in the Lower Cretaceous: alternation
of micritic spotty limestones with radiolaria and calpionellids, and shaly clayey
limestones with calpionellids and nannoplankton (Berriasian-Barremian), followed
above by sandy-glauconitic sediments (Aptian-Lower Cenomanian).
5.1.2 Dophinoise Area
This area represents an Early Cretaceous depression between the Central Massif
and the massifs of Mont Blanc, Belledonne and Mercantour. In southern direction
the depression widens and passes into the Vocontian trough. The depression is narrower
in the northern part and the sediments are thicker, e. g. at Cévennes the Berriassian-Hauterivian
sediments (subflysch) (1500-2000 m) are 5-6 times thicker
than in the Vocontian trough. Moreover, in the northern part the sediments are aleuritic
and / or slightly sandy, often with turbidites, whereas exclusively clayey-calcareous
sediments are developed in the south. A strip of neritic sediments encircles the
depression: in the northwest these are the high calcareous mountains of Savoy, the
massifs of Grande-Chartreuse and Vercors, and the environs of Valence; in the south—
the Languedoc and Provence.
The Lower Cretaceous in the Southern Subalpine Range (Vocontian trough)
is represented by pelagic sediments of Alpine type, unlike the neritic type in the Jura
Mountains. This is the only area in France, where deep-sea sedimentation existed
from the Berriasian to^the Albian and passed into the Cenomanian as well. In fact,
the Vocontian trough represents an enormous bay of the Subalpine Early Cretaceous
depression. Fine micritic limestones, clayey limestones and marls, rich in ammonites
and planktonic microfossils (calpionellids, radiolaria, foraminifera and nannoflora)
are developed there. This is the same facies in which the Lower Cretaceous
of the Salas -
syncline in Northwestern Bulgaria is developed.
The Northern Subalpine Range in which the Lower Cretaceous is developed
in mixed facies, starts to the north of Diois. To the north of the region around the
town of Die is the prominent high wall of the Urgonian limestones building the
southern end of Vercors and representing a characteristic element of this zone. The
Lower Cretaceous is represented by mixed facies — multiple repetition of biomorphic
limestones with marls. These sediments form the transition from the Vocontian
to the Jura-type facies of the Lower Cretaceous. All stages of the series are developed
and they are very well characterized palaeontologically. Particularly representative
is the section between Grenoble and Chambery.
5.1.3. Piémont Area
The Lower Cretaceous in this area is represented by a thick monotonous series of
"calcschistes" which were transformed into "schistes lustrés" during the Upper
Eocene-Oligocene under the effect of dynamometamorphosis. These "calcschistes"
are identified as Lower Cretaceous through comparison with a similar unmetamorphosed
formation in the Northern Apennines, which is dated to the Tithonian-
Neocoinian by calpionellids. The schists overlie green rocks — ophiolites (diabases
and spilites) and gabbro, being covered by radiolarites which are metamorphosed
into quartzites with sericite and chlorite, well revealed today at Mont Viso. The calcschistes
are covered by Upper Cretaceous flysch with helminthoids.
5.2. Provence
The Lower Cretaceous in Provence is represented by shallow-sea sediments: zoogenic
limestones, glauconitic sandstones with phosphorites and marls. The ammo-
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