(10) Facies analysis and depositional environments of the Miocene syn-rift carbonate-siliciclastic rock packages in the northwest Gulf of Suez, Egypt

摘要

The Miocene sedimentary successions in the northwest Gulf of Suez allow insight into the syn-rift deposition. These rocks are subdivided into three formations, namely the Sadat Formation coeval with the Gharra Formation (Early Miocene), the Hommath Formation (Middle Miocene), and the Hagul Formation (Late Miocene). The Miocene rocks in the study area are dominated by carbonate-siliciclastic packages. Detailed microfacies analysis permit discrimination of 14 sedimentary microfacies types, which are represented by continental quartz-arenites and sandy siltstones, as well as shallow-marine gypsiferous laminated shales, litharenites, dolomicrites, wackestones, wacke-/packstones, packestones, pack-/grainstones, ooidal/pelloidal pack-/grainstones, grainstones, rudstones, framestones, and bindstones. These microfacies types are stacked into four facies associations that represent fluvial, and inner ramp, shallow marine environments (facies associations for the later are restricted lagoonal/tidal flat, shoal bar, and open-lagoonal/reefal). In terms of sequence stratigraphy, it is possible to distinguish five depositional sequences in the studied Miocene succession. The retrograditional package displays predomi?nance of open lagoon/reefal facies. The aggradational package shows increase in restricted lagoon tidal flat and shoal bar facies. The progradational package marks occurrence of continental (fluvial) facies. The regional tectonic activity related to the rifting of the Gulf of Suez was the leading control of the Miocene sedimentation in the study area.