Abstract The basinal depositional architecture, paleobathymetry and paleoproductivity assessment of west central Sinai (Egypt) lacks robust sequence stratigraphic framework inferred in conjunction with changes in benthic foraminiferal biofacies. Sinai is an economically important region for hydrocarbon exploration, hence understanding its depositional architecture is fundamental. For this, the planktic foraminifera biostratigraphy is done first to date the strata exposed at Wadi Nukhul, and then, the quantitative benthic foraminiferal biofacies are evaluated to infer changes in paleobathymetry and paleoproductivity. Five Eocene planktic biozones identified (E7b to E11), spanning 48.6 to 40.4 Ma are identified along with five 3rd order depositional sequences bounded by four sequence boundaries. Quantitative (Rotated factor analysis) benthic foraminiferal analysis revealed seven benthic foraminifera biofacies (A to F) suggesting a meso- to eutrophic, outer neritic, moderate to low oxygenated bottom waters, dominated largely by benthic foraminifera taxa, Bulimina, Uvigerina, Bolivina and Lenticulina. Exception to this trend is the presence of biofacies B (Discorbis ciperensis-Lenticulina cuvillieri) at the top of the Thebes Formation that reflects well‑oxygenated bottom waters straddling the middle to outer neritic depth boundary. The inferred relative sea level gradually decreases throughout the studied section (from bottom to top) and is consistent with a gradual global decline. Of interest is the possible identification of the Middle Eocene Climatic Optimum (~40.5–40 Ma), a global warming event that in the present study, encompasses the Uvigerina mediterranea-Spiroloculina esnaensis biofacies (Biofacies A) suggesting the presence of mesotrophic but moderately well‑oxygenated bottom waters at outer neritic depths. The base of the Thebes Formation is marked by the presence of an Oxygen Minimum Zone.

中文翻译：

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定量的中始新世底栖有孔虫生物相来自埃及西奈半岛中西部：对古水深测量和层序地层学的影响

摘要 西奈半岛中西部（埃及）的盆地沉积结构、古水深测量和古生产力评估缺乏结合底栖有孔虫生物相变化推断的可靠层序地层框架。西奈半岛是油气勘探的重要经济地区，因此了解其沉积结构至关重要。为此，首先进行浮游有孔虫生物地层学以确定 Wadi Nukhul 出露地层的年代，然后对定量的底栖有孔虫生物相进行评估，以推断古水深测量和古生产力的变化。确定了五个始新世浮游生物区（E7b 到 E11），跨越 48.6 到 40.4 Ma，以及由四个序列边界界定的五个三级沉积序列。定量（旋转因子分析）底栖有孔虫分析揭示了七个底栖有孔虫生物相（A 到 F），表明存在中到富营养化、外浅海、中低含氧底水，主要由底栖有孔虫类群、Bulimina、Uvigerina、Bolivina 和 Lenticulina . 这种趋势的一个例外是底比斯组顶部存在的生物相 B（Discorbis ciperensis-Lenticulina cuvillieri），它反映了横跨浅海中部到外部深度边界的含氧良好的底部水域。推断的相对海平面在整个研究部分（从底部到顶部）逐渐下降，并且与全球逐渐下降一致。有趣的是可能识别出中始新世气候最优（~40.5-40 Ma），这是一项全球变暖事件，在本研究中，包括 Uvigerina mediterranea-Spiroloculina esnaensis 生物相（生物相 A），表明在浅海外层深度存在中营养但含氧量中等的底水。底比斯地层的底部以存在最低含氧量区为标志。