Early Cretaceous palynofloras from the Bongor basin, Chad, and their palaeoenvironmental and palaeoclimatic significances

Abstract

A systematic palynological investigation of borehole core and cutting materials enable the correlation of twenty-three wells in the Lower Cretaceous Bongor Basin, Chad. These borehole samples are dated as Early Cretaceous and three ascending palynological zones are recognized, the upper Hauterivian to lower Barremian Dicheiropollis Total Range Zone (I), the upper Barremian Sergipea–Zhonghuapollis Assemblage Zone (II), and the Aptian Afropollis–Pilosisporites–Ephedripites–Cicatricosisporites Assemblage Zone (III). A new species of gymnosperm pollen, Sergipea multipapillata sp. nov., is described from the palynoflora of the Bongor Basin. Regional stratigraphic correlation based on palynofloras of Lower Cretaceous is given between the Bongor Basin and its neighbouring area. In the Early Cretaceous the Bongor Area was an inland sedimentary basin, the changes in the palynoflora indicate changing patterns of vegetation, the palaeoclimate is reconstructed as mainly hot and arid, with seasonal precipitation and transient warm and humid breaks.