Palynomorph succession and paleoenvironment in the Upper Cretaceous Abu Gharadig Oil Field, Northwestern Desert, Egypt

摘要

An Upper Cretaceous spore-pollen and dinoflagellate zonation in two deep wells (AG-5 and AG-13) of the Abu Gharadig oil field, Northwestern Desert, Egypt is presented. Six pollen and spores zones equivalent to five dinoflagellate and phytoplankton zones are defined for the Cenomanian-Santonian Bahariy a and Abu Roash formations. One new pollen species, Integritetraditesfoveolatus sp. nov., is described from the middle to late Cenomanian strata. The Cenomanian-Turonian boundary is defined for the first time in Egypt using stable carbon and oxygen isotopes (δ~(13)C and δ~(18)O), where a positive carbon excursion is detected in organic rich shale of the basal Abu Roash "F" Member. During the Cenomanian, Egypt was part of the mid-Cretaceous "African-South American" Province (ASA), characterized by dominance of Classopollis, Araucariacites, eleter-bearing and Afropollis pollen assemblage in an arid to semi-arid warm climate. The marine/terrestrial palynomorph ratio increased upward from the Cenomanian to Santonian related to a global sea level rise. The Cenomanian siliciclastics of the Bahariya Formation and the basal Abu Roash G and F members were deposited in a shallow marine, inner shelf environment. The Middle part of the Abu Roash Formation (E member: Turonian) is a shallow water, middle shelf deposit, while the upper part of the Abu Roash Formation (A, B, C and D members: Coniacian-Santonian) are open marine, outer shelf deposits.