Biostratigraphic and Palaeoenvironmental Study of the Tobène Phosphatic Series ( Western Senegal )

The geological section of the phosphate quarry of Tobène associated with the boreholes of prospecting, carried out by miners, confirms the Tobène’s lithostratigraphic and biostratigraphic settings. A lithostratigraphic analysis [1], [2] highlights three sedimentary formations, in agreement with previous results [3]. From a biostratigraphic point of view, the planktonic microfauna highlighted E8 to E13 biozones in the phosphatic group, dating it to the early Lutetian to Bartonian age and helping to develop a more complete biozonation throughout the deposit. The pelagism index indicates an evolution of sedimentary environment between a slightly opened internal platform, favourable to detrital and siliceous deposits, and an intermediate platform more conducive to calcium phosphate deposits.