THE MEDITERRANEAN LOWER CRETACEOUS

Acanthohoplites sp., charophytes and foraminifera: Ticinella bejaouaensis Sig.,
Globigerinelloides algerianus (C u s h., Da m.) and G. ferreolensis (Moul 1.),
occur (Wiedmann et al., 1978).
The Albian is built of greenish marls with many planktonic foraminifera: Planulina
buxtorfi (Can d.), Rotalipora apenninica (Ren z), Ticinella primula L u 11
and Ticinella sp., as well as nodosarids (Lenticulina) and ostracods. The macrofauna
is scarce. Douvilleieeras mammillatum (S с h 1.), Beudanticeras spp., Oxytropidoceras
(0.) sp., Hysteroceras orbignyi Spath, Mortoniceras falax Spath, Paraturrilites
bergeri (P i с t., Cam p.) and Stoliczkaia dispar (d'O r b.) are found
(Wiedmann et al., 1978). The bio- and lithofacies indicate deepening of the
shelf basin.
In the northeastern part of the Agadir zone (Tizi region), in the High Atlas,
the upper part of the Lower Cretaceous (Barremian-Albian) is of regressive type.
The Upper Barremian and the Lower Aptian contain predominantly clastic sedilnents
of epicontinental type (reddish aleuritic claystones, sandstones, dolomites
and conglomerate lenses). According to Butt (1982), these sediments are crossbedded,
with core structures and traces of submarine slides. This is evidence of
deltaic facies formed in the littoral zone. The organism remains consist of varied
detritus, as well as charophytes, small ostracods and agglutinated foraminifera
(Ammobaculites).
In the same Tizi region the described clastic deltaic facies of the Upper Barremian-Lower
Aptian is "covered by a typical condensed section of the Upper Aptian
and the Albian. Limestones, sandstones, aleuritic marls and in some places
dolomites are developed, among which there are ammonites and different foraminifera
(Nodosaria, Lenticulina and Hedbergella), as well as agglutinated forms
(Haplophragmium, Ammodiscus and Reophax). The fauna becomes poorer higher
up in the section and only in the uppermost part of the Albian there is an abundance
of planktonic foraminifera. The lithological transition to the Cenomanian
is gradual.
In the north, in the Essaouira area, the lower part of the series is very similar
to the sections in the Agadir zone. Over the shallow-marine Upper Tithonian limestones
there are aleuritic marls in alternation with limestones containing Berriasian,
Valanginian and Lower Hauterivian ammonites, as well as a rich association of
foraminifera, among which the nodosarids are very varied (W i e d m a n n et
al., 1978; Butt, 1982). According to Butt, the foraminifera indicate a deep middleshelf
environment, similar to that of the Agadir zone. A sharp shallowing started
during the Early Hauterivian, which is indicated by the development of coloured
(mainly red) sediments containing small bivalvs, gastropods and rare agglutinated
foraminifera (Ammobaculites). This biofacies demonstrates lagoon and brakish
epicontinental regressive environment (Butt, 1982). Marls with ammonites and
many foraminifera are developed higher up in the section of the Upper Hauterivian
and in the Barremian indicating typically marine environment in the middle shelf.
The Lower Aptian is connected with continental sandstones and conglomerates
(red beds) which are covered by marls and aleuritic claystones with foraminifera
(Gargasian Substage), followed higher up by olive-green and yellow-green aleuritic
and sandy marls with ammonites and many foraminifera (Upper Aptian-Albian).
The faunistic content and especially the P/'B ratio in the foraminifera indicates
a relatively deep and calm middle shelf (Butt, 1982).
The Late Albian marks the start of the deposition of carbonate sediments,
among which ammonites and planktonic foraminifera disappear.
In the north, at Safi, the Lower Cretaceous is developed in marine facies (Berriasian-Aptian).
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