Abstract

The study of the Turonian formations outcropping along the Congolese coast was undertaken in the order of to understand the sequential organization of the deposits as well as the evolution of the paleoenvironments. The study consisted of a detailed description of the lithofacies in the field and in the laboratory. This study shows that these formations are essentially made up of silty dolomites, formed in a littoral environment where the waters were favorable to the multiplication of planktonic foraminifers, Lamellibranchs and Brachiopods. The sedimentological characteristics indicate a sudden retreat from the shore, witnessed by the various regressive elementary sequences. These elementary sequences each begin with a layer of thanatocenosis which would be due to a sudden change of environment, consequence of an important arrival of detrital terrigenous sediments. This terrigenous detrital contribution disrupts each time the physicochemical characteristics of the environment (oxygen deficiency, absence of light, high turbidity). The fauna of these formations exhibits a coniacian affinity. The sequential evolution of the deposit shows a large ravine unconformity on the top of the mega sequence. The composition of the fauna and the sedimentological characteristics confirm the existence of a regressive sedimentation model of the Lower Coniacian age.

Keywords:

Bivalves, lumachelle, regression, sedimentology, thanatocenosis,

References

Competing interests

The authors have no competing interests.

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The authors have no competing interests.