Assemblage changes of foraminifera and palynomorphs across eocene - oligocene boundary in Southern Tanzania

A quantitative micropaleontological analysis was performed on outcrop and core samples split across a shallow boreholes (TDP 11) drilled by the Tanzania Drilling Project (TDP) Team in Southern Coastal Basins of Tanzania, yielding a recovery of 158 and 57 foraminifera species for the core and outcrop samples respectively and more than 30 species of palynomorphs were recognized. TDP 11 (UTM 37L; 560250/ 8983211) was drilled on Pande Formation and outcrop samples were collected from Mandawa basin in Pande Formation and Namandigura River (UTM 37L; 577270/ 8904844). The sediment successions cover the late Eocene to early Oligocene, with olive to greenish grey claystone principal lithology. Foraminifera recovery range from <38 to 261 specimens per gram while palynomorphs recovery range from < 5 to < 40 for a single analysed slide. Two planktonic foraminifera Biozone were recognised such as Hantkenina alabamensis and Pseudohastigerina naguewhiensis Biozones. The late Eocene-early Oligocene transional boundary (34 Ma) is placed by the last appearance (LA) of Hantkenina alabamensis. The palynomorphs and foraminifera assemblages recovered and planktonic/benthic (P:B) ratio shows a good succesion of data which was used in interpreting the paleoenvironment settings of Pande Formation during the late Eocene to early Oligocene period. The P:B ratio, benthic foraminifera assemblages and palynomorphs assemblages indicate the deposition environmrent as ranging from inner to middle shelf (shallow marine) environment.