Paleoenvironmental and Palynofacies Insights from Lower Cretaceous Strata in the Obaiyed Field, Shushan Basin, North Western Desert, Egypt

Semi-quantitative and qualitative analyses of the total particulate organic matter (TPOM) constituents in nineteen cutting samples from the Lower Cretaceous successions of the OBA D-8 borehole, Obaiyed Field, Shushan Basin, north Western Desert of Egypt. The analyses were conducted to identify the prevailing palynofacies and paleoenvironments. The combined data derived from the palynofacies assemblages and palynomorphs groups, the ternary plots along with the lithological composition indicate two palynofacies (PF) units; they are PF-1 and PF-2. PF-1was corresponds to sediments recovered from the clastics of the Alam El Bueib Formation. These sediments were situated in a marginal marine (deltaic) environment during a marine regression phase, with suboxic-anoxic to oxic settings, resulting in poor to relatively good organic matter preservation status. PF-2 corresponds to sediments recovered from the Alamein (mixed clastics-carbonates) and the Dahab and Kharita clastics formations. Sediments of PF-2 were deposited during a progressive marine regression phase beneath suboxic to anoxic conditions in an inner marine habitat. Sea level rose during the Late Valanginian-Hauterivian; the Aptian high stand and the Albian high stand were superimposed by the Early Cretaceous uplift (Valanginian-Albian) associated with the rifting of the Shushan Basin.