THE MEDITERRANEAN LOWER CRETACEOUS

Specificilly good faunistic successions are known from the Ida (Tanan) area,
east of Cape Rhir (H a u g, 1908; 1911).
Valanginian: Thurmanniceras thurmanni (P i с t., С a m p.), Neocomites neocomiensis
(d'O г b.), Olcostephanus spp., bivalvs, gastropods and brachiopods.
Hauterivian: Acanthodiscus radiatus (В г.), Leopoldia kiliani (Кое п.), L. biassalensis
(К а г.). Olcostephanus astierianus (d'O г b.), Pseudothurmannia angulicostata
(d'O r b.), Duvalia dilatata (В 1.), bivalvs, gastropods and brachiopods.
Barremian: Pulchellia compressissima (d'O r b.), Barremites difficilis (d'O r b.),
Barremites spp. and Heteroceras sp. Bivalvs and brachiopods are well represented.
The Aptian is developed in its full volume and is characterized by Cheloniceras
(C.) cornuelianum (d'O r b.), Procheloniceras stobiecki (d'O r b.), Deshayesites deshayesi
(Ley m.), Aconeceras nissum (d'O г b.), Toxoceras cornuelianum (d'O r b.),
Gargasiceras sp., Parahoplites melchioris A n t h., Acanthohoplites aschiltensis (Ant h.),
A. akuschaense (Ant h.), A. bigoureti (S e u п.), Colombiceras tobleri (J a c.), Diadochoceras
nodosocostatum (d'O r b.), etc.
The upper and middle parts of the Aptian are very well characterized faunistically
in the Marrakech valley.
In the Meseta area the Lower Cretaceous is developed in a Wealdean-like continental
facies, divided by a sea ingression during the Valanginian. Sandstones and
red claystones are represented, which are assumed grosso modo to be Lower Cretaceous,
because they overlie the Upper Jurassic rocks and are covered transgressively
by marine Cenomanian deposits. The Valanginian is represented by dolomite
limestones containing rich ammonite fauna (W i e d m a n n et al., 1978).
The Moroccan Reef area lies approximately to the north of the Rabat parallel.
Its shores are washed by the Atlantic Ocean to the west and by the Mediterranean
Sea to the north. The eastern boundary of this area is the valley of the Oued Moulouya
river, after which the Tellian Atlas starts.
In the southern part of the Reef the Lower Cretaceous starts with the Berriasian,
connected with a lithological transition to the Tithonian. It is represented by finegrained
biomicrites, rich in Calpionella, Nannoconus, Calcisphaeridium, radiolaria,
smooth-shell ostracods and various detritus; pelletic limestones and core limestones
("Ammonitico-Rosso" type) with many ammonites; microbreccias, in some places
with graded bedding and intraclastic limestones. The bio- and lithofacies indicate
hemipelagic environment of external shelf (W i e d m a n n et al., 1982).
The beginning of the Valanginian is marked by a sudden transition to clayeycalcareous
sediments (calcareous claystones, marls and clayey limestones) with many
ammonites, calpionellids and radiolaria. The calpionellid zones Calpionella, Calpionellopsis
and Calpionellites are discovered in the Berriasian-Valanginian (W i e dm
a n n et al., 1982).
In the north, in the coastal zone of the Reef (Dorsale rifaine), there are clayey
limestones, rich in radiolaria, nannoplankton, calpionellids and aptychi, which permit
the differentiation of Lower Cretaceous stages — from the Berriasian to the Barremian
included. These sediments overlie Jurassic, most frequently Lower Jurassic
rocks. They reach up to 50 m in thickness. Green glauconitic Albian marls are found
in the Haouz—Dorsale intern area.
In the allochthonous part of the Reef the Lower Cretaceous is developed in
f lysch facies which are not stratigraphically divided due to lack of good fossils (D urand
Delga, 1965b). The Berriasian is represented by clayey-calcareous sediments,
such as Tithonian. The sedimentation of turbidites started toward the end
of the Berriasian and continued uninterrupted throughout the entire Early Cretaceous.
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