Early Cretaceous Dinoflagellate Cysts And Miospores From The Mersa Matruh 1 Borehole, North West Desert, Egypt

Abstract

This study aims to document the Neocomian to Aptian palynological assemblages recorded in the Mersa Matruh borehole, north West Desert, Egypt. These palynological assemblages, consisting mainly of dinocysts, miospores and very rare acritarchs are used to interpret four stratigraphic phases of environmental changes in the Early Cretaceous sequence. Phase I from depth 12222 ft to 14923 ft is dated as Neocomian to early Barremian, and is interpreted to have been deposited under fully marine conditions in its basal part and under near-shore marine environment in the Barremian horizon. Phase II at depth 11824 ft -11833 ft was dated as ? late Barremian. The palynoflora in this horizon suggests a possible regression. The succeeding phase III is dated as late Barremian to early Aptian and is interpreted to have been deposited under inner and middle shelf conditions. The overlying phase IV has been dated as ? late Aptian. Changes in the palynomorph composition in the upper part of phase HI within the Matruh Shale and phase IV within the Kharita Member indicate an episode of regression, which is inferred from an increase in the terrestrially-derived palynoflora.