Miocene facies models, paleoenvironments and sedimentary cycles in the Nile Delta area, Egypt

Abstract

Lateral and vertical distribution of lithofacies and paleoenvironments of the Miocene sequence in the Nile Delta and its eastern adjoining area enabled recognition of the depositional history and eustatic sea level changes. Three successive cycles of sedimentation are deduced. The first cycle took place by the end of Oligocene and during the Early Miocene. The sequence of this cycle started with inner neritic facies succeeded by open bathyal facies, implying a transgressive marine cycle. The second cycle indicates a progressive regression of the sea from bathyal to transitional and continental environments during the Middle and Late Miocene. The third cycle developed in the Late Miocene-Early Pliocene and is characterized by transgressive sequence of transitional facies succeeded by neritic and bathyal facies. The proposed Miocene eustacy in the Delta area is compared with the global eustatic sea level changes. It is interesting to note that the first and third transgressive cycles were controlled by global eustatic rises in the sea level and the second regressive event was related to local active tectonics. The effects of syndepositional fault activation are demonstrated in the middle and upper Miocene sediments.