Leiosphaeridia and Pterospermella acritarch genera as shallowing phase indicators in the early Jurassic, North Sinai, Egypt

The first attempt in Egypt to throw the light on the importance of Leiosphaeridia and Pterospermella acritarch genera has been done in the present study. Five ditch-cutting samples collected from the Mashabba Formation in North Sinai have been palynologically investigated. This study demonstrates the stratigraphic importance of these genera in the Jurassic sediments and increases their value in future sequence stratigraphical and paleoenvironmental/paleoecological interpretations. Both genera in the subsurface Early Jurassic interval of the Mashabba Formation indicate shallow water conditions. A good relationship between the recovery of these genera and the coarsening of the clastics has been recognized. Moreover, high counts of these acritarchs genera correlate with the increasing of sand content and vice versa. Hence, the abundance of Leiosphaeridia and Pterospermella can be an indication of the regressive events and associated low/fall sea levels in the Early Jurassic of Egypt.