Open Session - SWISS GEOSCIENCE MEETINGs

122
Symposium 3: Palaeontology
3.
Fossil assemblages from the early Late Cretaceous of southeast Morocco
Cavin Lionel *, Meister Christian*, Piuz André* & Boudad Larbi**
* Dpt de Géologie et Paléontologie, Muséum de Genève, CP 6434, 1211 Genève 6, Suisse
** Faculté des Sciences et Techniques, BP, 509, Boutalamine, Errachidia, Maroc
The Cretaceous deposits surrounding the northern, eastern and southern borders of the Palaeozoic Tafilalt and Mader basins
have yielded numerous fossils for more than fifty years. First surveys by French geologists recorded Cenomano-Turonian
ammonite assemblages (Basse & Choubert 1959), fish fragments in Turonian of the High Atlas and Midelt area (Dubar 1949),
continental reptiles remains in the ‘Grès Infra-cénomaniens’, or ‘Continental Intercalaire’ of the Kem Kem region (Lavocat
1948, 1949).
During the following decades, only few palaeontological data about the ‘mid-Cretaceous’ of that area have been published.
During the last thirty years, however, local people have engaged very active excavation works for collecting Cretaceous fossils
for commercial purpose. Beautifully preserved specimens have been discovered by this way, but little information about sedimentological,
startigraphic and geographical contexts is usually associated with this material.
Here we present preliminary results of fieldworks conducted by the authors in 2008. The goal of this study is to better understand
the palaeoenvironmental and startigraphic contexts of the ‘mid-Cretaceous’ transgression in North-west Africa. In
this study, we focused on microfossils, ammonites and fishes as indicators of age and environment changes.
We sampled in eight main localities along a north-south transect within the basin in order to detect lateral variations. The
series started with continental and deltaic deposits (fig. 1), regarded as Albian-Cenomanian in age, which are topped by
coastal then open marine deposits (fig. 2) corresponding to the Cenomanian-Turonian major transgression.
Figure 1. Albian-Cenomanian continental and deltaic deposits at the base of the series, Taouz (photo Cavin, L.).
Figure 2. Cenomanian-Turonian marine deposits at the top of the series, Belkassem (photo Piuz, A.).