BIOSTRATIGRAPHIC CHARACTERIZATION OF THE CRETACEOUS DEPOSITS OF THE SAN-PEDRO MARGIN OF DRILL HOLES K1 AND K2 OF BLOCK KL: PALEOENVIRONMENT IMPLICATION

The KL block studies was carried out the eastern part of the San Pedro margin, it has an area of 2034 km2 with a water depth varying from 500 to 2750 m with two probings (K1 and K2).The objective of this work is to carry out a biostratigraphic and paleoenvironmental study based on the associations of planktonic and palynomorphicmicrofauna in the formations of the KL block boreholes. From a lithological point of view, the base of the boreholes generally comprises alternating limestone and argillite, very fine to fine grained quartz sandstone. Its upper part is overlain by claystoneinterbedded with limestone, silstone and siliceous cemented sandstone and alternating claystone, medium to coarse grained sand and siliceous cemented quartz sandstone. The Albian is determined by the presence of the species Ticinellamadecassiana. The Cenomanian is identified by the micropalaeontological assemblages composed of Globigerinelloides spp., Guembelitria spp., Hedbergella spp., Hedbergelladelrioensis, Globigerinelloides bentonensisandLoeblichella cf. hessi. The Turonian is based mainly on the species Hedbergellaplanispira, Heterohelixmoremani and Whiteinella archaeocretacea. The Early Senonian is characterized by associations of species (Hedbergellasp, Hedbergella cf. delrioensis, Buliminacrassa and Whiteinella baltica) and palynomorphs (Proteaciditestienabaensis, Odontochitinacostata, Odontochitinaporiferaand Tricolpites sp). The roof of the Campanian is known by the association of the palynomorph (Trichodinium castanae) and the microfossil (Gaudryina cretacea) The Maastrichtian is highlighted by the associations composed of species Rzehakina epigona fissistomata, Rzehakina minima, Plectina lenis, Reophax duplex, Reophax pilulifera, Reophax globosus, Gaudryina pyramidata and Afrobolivina afra) and palynomorphic species (Andalusiella gabonensis, Cerodinium granulostriatum and Palaeocystodinium australinium). All the micropalaeontological data coupled with those of the microfaunas make it possible to envisage a depositional environment of the internal platform type with continental influence on an external platform.