Sequence stratigraphy of the Miocene siliciclastic-carbonate sediments in Sadat Area, north-west of Gulf of Suez: Implications for Miocene eustasy

摘要

The Miocene sequences in the north-west of the Gulf of Suez represent transition zones between carbonate-dominated and siliciclastic-dominated strata. These rocks were greatly influenced by the Gulf of Suez rifting, which resulted in lateral variations of facies and hence presented a complicated stratigraphic setting. Here, we interpret the sequence stratigraphy of the Sadat Area to the north-west of the Gulf of Suez by integrating biostratigraphic data and microfacies analysis to contribute primarily to the geology of the studied successions and incorporate the existing knowledge of syn-rift deposition. We determined the ages of the studied formations by biostratigraphic examination of the integrated calcareous nannoplankton, planktic, and benthic foraminifera. Our results distinguish four genetic Miocene sequences. These sequences are defined by four major sequence boundaries that outline sedimentation cycles and were chiefly deposited in a lagoon to outer-shelf settings. The proposed Miocene eustacy is well-correlated with global curves, implying a rise in sea level in the lower parts of Zones M4, M5, and M8. In contrast, the reduction of sea-level rise resulted in the decrease of accommodation space in the upper part of Zone M5. The studied Miocene deposits mainly formed in a shallower marine environment, as shown by a comparison between data from the eastern side of the Gulf of Suez and the data presented in this paper. Furthermore, we demonstrate that the local tectonic activity linked with the Gulf of Suez rifting and the eustatic sea-level changes were significant factors in the deposition of the Miocene in the studied successions.