干旱区生态环境知识资源中心

We have applied facies analysis and an integrated stratigraphic approach to make a detailed study of the Cenomanian-Turonian successions of the Eastern Desert of Egypt. A detailed ammonite biozonation is constructed that allows precise correlations. The predominantly shallow-marine successions include the Galala, Maghra El Hadida, and Umm Omeiyid formations, which represent a shallow-marine, mixed carbonate-siliciclastic open lagoonal to carbonate ramp setting. Six major sedimentary unconformities (Cenomanian sequence boundaries SB Ce 4 and 5, and Turonian sequence boundaries SB Tu 1-4) have been recognized and laterally tracked across the Eastern Desert. Their stratigraphic positions have been calibrated by means of ammonite biostratigraphy and they define five third-order depositional sequences (DS ED 1-5). The sequence-stratigraphic calibration of the study area with successions from other Cretaceous basins demonstrates the contemporaneity of the unconformities across different tectonic plates, strongly suggesting that the formation of these successions resulted from eustatic sea-level changes.