Palaeoenvironmental and source rock potential of the Turonian–Miocene sequence in the West Esh El Mellaha (SW margin of the Suez rift, Egypt): Insights from palynofacies, palynology and organic geochemistry

Abstract

A detailed palynological, palynofacies and geochemical study has been undertaken on cuttings samples selected from wells drilled in the Gulf of Suez, Egypt. Inter alia, the samples yielded marine palynomorphs, non-marine palynomorphs, amorphous organic matter (AOM) and phytoclasts. Deposits of the Matulla Formation are dated as Coniacian–Santonian based on the angiosperm pollen and dinoflagellate cyst content. Angiosperm pollen Areolipollis vespiformis in the Rudeis Formation is taken as a biostratigraphic marker for the early Miocene.Two palynofacies associations were identified. Association-A from the Matulla and upper Rudeis formations consists mainly of Type-III gas-prone kerogen. Association-B contains Type-II and Type-II/III kerogens with mixed oil and gas, and is typical of Duwi, Esna, Thebes and lower Rudeis samples. Samples were deposited under various dysoxic–anoxic and suboxic–anoxic conditions.The peridiniacean assemblage from the Upper Cretaceous Matulla Formation intimates deposition in a tropical to subtropical setting within the Tethyan Realm of the Malloy Suite. Salixipollenites, fern spores, and dinoflagellate cysts suggest successive phases of humidity versus aridity during the early Miocene.Geochemical data show that samples from the Duwi Formation are Type-II and Type-II/III kerogens. Based on low HI values and low abundance of AOM, palynofacies association-A samples indicate Type-III gas-prone kerogen, whereas association-B samples have the greatest values of HI and AOM, indicating oil-prone Type-II to Type-II/III kerogens.