A geochemical analysis has been conducted on twenty-six sediment samples spanning the P–E boundary interval collected from the Esna Shale in three well-dated stratigraphic sections in west-central Sinai, Egypt to interpret paleoenvironmental changes associated with the P–E boundary events. The Esna Shale consists of hemipelagic marine shales and marls and it is subdivided stratigraphically into the uppermost Paleocene Hanadi Member unconformably overlain by the lowermost Eocene Dababiya Quarry Bed (DQB) and El-Mahmiya members. A variety of geochemical proxies including the Al-normalized elemental concentrations and redox-related elemental ratios and parameter (V/Cr, V/V + Ni and Mn*) and productivity indicators (Porg and Babio) were employed for paleoceanographic interpretations. Across the P–E transition, the concentrations of SiO2, TiO2, Al2O3 Fe2O3, MgO, V, Cr, Ni, Cu, Rb, and Zr notably increased, whereas the concentrations of CaO, MnO, Sr, and Zn abruptly decreased. The variation in the elemental concentrations is attributed to the carbonate dissolution because of increased ocean acidification as well as a brief increase in the detrital influx associated with the brief humid interval at the base of the Eocene. The Al-normalized detrital-related elements (Ti, Zr, and Rb) values show a relatively homogeneous profile suggesting a uniform detrital input from an unchanged source rock. The simultaneous significant increase in the V/Cr and V/V + Ni ratios and enrichment of Ni, Cu, and Zn in the sediments of the DQB suggest that the depositional basin experienced dysoxic to slightly anoxic bottom conditions. The coeval increase in the Porg and Babio in the sediments of the DQB suggests an increase in nutrients availability and consequently primary productivity possibly due to enhanced upwelling during early Eocene.

中文翻译：

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埃及西奈中西部古新世-始新世边界的古环境变化：地球化学代理

已对埃及西奈中西部三个良好地层中从埃斯纳页岩采集的跨越P–E边界层的26个沉积物样品进行了地球化学分析，以解释与P–E边界事件有关的古环境变化。 。埃斯纳页岩由半海相海相页岩和泥灰岩组成，地层细分为最上层的古新世Hanadi成员，最下层的始新世Dababiya采石场（DQB）和El-Mahmiya成员覆盖了该层。多种地球化学指标包括Al归一化元素浓度和氧化还原相关元素比率以及参数（V / Cr，V / V + Ni和Mn *）和生产率指标（Porg和Babio）用于古海洋学解释。在整个P–E过渡过程中，SiO2，TiO2，Al2O3 Fe2O3，MgO，V，Cr，Ni，Cu，Rb和Zr显着增加，而CaO，MnO，Sr和Zn的浓度急剧下降。元素浓度的变化归因于碳酸盐溶解，这是由于海洋酸化增加以及与始新世基底短暂的湿润间隔有关的碎屑涌入量的短暂增加。Al归一化碎屑相关元素（Ti，Zr和Rb）的值显示出相对均匀的轮廓，表明来自未改变的烃源岩的均匀碎屑输入。DQB沉积物中V / Cr和V / V + Ni比值的同时显着增加以及Ni，Cu和Zn的富集表明该沉积盆地经历了低氧至轻度缺氧的底部条件。