PALYNOLOGY AND PALEOENVIRONMENT OF THE UPPER CRETACEOUS ROCKS FROM ABU GHARADIG OIL FIELD, NORTH WESTERN DESERT, EGYPT

An integrated Upper Cretaceous spore-pollen and dinoflagellate zonation in two deep wells (AG-5 and AG-13) of the Abu Gharadig oil field, North Western Desert, Egypt is presented. Five zones of pollen and spores equivalent to six dinoflagellate and phytoplankton zones are defined for the Cenomanian-Santonian Bahariya and Abu Roash formations. The Cenomanian-Turonian boundary is defined for the first time in Egypt using stable carbon isotope δ13C, where a positive carbon excursion is detected in organic rich shale of the basal Abu Roash "G" Member. During the Cenomanian, Egypt was part of the mid-Cretaceous "African-South American" Province (ASA), characterized by dominance of Classopollis, Aruacariacites, elater-bearing and Afropollis pollen assemblage of arid to semi-arid climate. The marine/terrestrial palynomorph ratio increased upward from the Cenomanian to Santonian as indication of sea level rise. The Cenomanian clastics of the Bahariya Formation and the basal Abu Roash G Member were deposited in shallow marine, inner shelf environment. The Middle part of the Abu Roash Formation (D, E and F members: Turonian) are shallow water, middle shelf deposits, while the upper part of the Abu Roash Formation (A, B, and C members: Coniacian-Santonian) are open marine, outer shelf deposits.