Sequence stratigraphy of the upper Oligocene-middle Miocene succession in west-central Sinai, Egypt

The calcareous nannofossil and foraminiferal analyses have been integrated to build a detailed chronostratigraphic scheme for the upper Oligocene-middle Miocene succession in the Nukhul-Sudr area, west-central Sinai, Egypt. The palaeoenvironmental conditions of the studied succession were assessed using the palaeoecologic preferences of calcareous nannofossil species, benthic foraminifera, and planktonic/benthic (P/B) ratios. Six complete and two incomplete depositional sequences bounded by seven sequence boundaries have been distinguished in the studied sections based on the integration between chronostratigraphic and palaeoenvironmental interpretations as well as the nature of stratigraphic surfaces. Levels suggesting subaerial exposures (such as alluvial fans and polymictic conglomerates) and biostratigraphic breaks were employed to delineate sequence boundaries. The inferred relative sea-level curve points to palaeodepth change ranging from lagoonal to outer shelf settings during the deposition. The established upper Oligocene-middle Miocene sequence stratigraphic framework demonstrates a more-or-less compatible correlation toward the corresponding ones from the neighbouring localities around the eastern rim of the Gulf of Suez. However, the inferred relative sea-level curve shows significant deviations when compared with the eustasy. These deviations are expressed mainly by several prolonged time gaps and discrepancies in the timing and magnitude of the transgression and regression events. Therefore, the Gulf of Suez rift Basin development and the coincident regional tectonic events are the main controlling factors for the sedimentation regime in west-central Sinai.

Automated summary

The calcareous nannofossil and foraminiferal analyses have been integrated to build a detailed chronostratigraphic scheme for the upper Oligocene-middle Miocene succession. The palaeoenvironmental conditions were assessed using the preferences of calcareous nannofossil species and foraminifera, indicating the influence of regional tectonic events on the sedimentation regime.