The vertebrate fossil-bearing upper Eocene strata in the Fayum area, Egypt exhibit complex lateral facies variations making their stratigraphy and depositional setting a matter of debate. They are exceptionally well exposed in the Kom Aushim Quarry region, NE Fayum, where they have hitherto been rarely studied. A recent study in a nearby locality had imposed a tide-dominated delta for these strata. The present study provides insight into this sedimentary succession and introduces an updated sedimentological interpretation of the Umm Rigl Member; basal Qasr El-Sagha Formation relying on outcrop facies analysis and sequence stratigraphic data. Eight short stratigraphic sections were measured and fully described in terms of lithology, grain size, stratal boundaries and sedimentary structures. The mud-dominated lower unit of the Umm Rigl Member consists of four vertically stacked shallowing/coarsening upward bay-margin/lagoonal deltas. The strata in the upper unit of the Umm Rigl Member are interpreted as incised valley back infilled with fluvial, upper estuary, tidal flat passing upwards into shallow and open marine deposits. The strata represent two incomplete depositional sequences, separated by a sequence boundary defined by an abrupt basin-ward shift of facies and equates with the base of incised valley previously recognized in Wadi Al-Hitan area. This boundary may equate with the early Priabonian Pr-2 global sea-level fall. Based on transgressive stacking of facies, the strata of the upper unit are interpreted as estuarine rather than deltaic system. This updated interpretation enhances understanding of depositional history and the paleogeographic evolution of NE Fayum during the late Eocene.

埃及Fayum地区的含脊椎动物的始新世上新世地层表现出复杂的侧相变化，这使得它们的地层和沉积问题引起了争论。它们在NE Fayum的Kom Aushim采石场地区异常地暴露，迄今很少对其进行研究。最近在附近地区进行的一项研究对这些地层施加了以潮汐为主的三角洲。本研究为这种沉积演替提供了见识，并介绍了Umm Rigl成员的最新沉积学解释。基底Qasr El-Sagha组依靠露头相分析和层序地层资料。测量了八个短的地层剖面，并就岩性，晶粒度，地层边界和沉积构造进行了全面描述。Umm钻机部件的以泥浆为主的下部单元由四个垂直堆叠的浅层/粗化向上的海湾边缘/泻湖三角洲组成。Umm钻机构件上部单元中的地层被解释为切开的河谷背，里面充满了河流，上河口，潮汐平面，向上进入浅而开放的海相沉积。地层代表了两个不完整的沉积层序，被一个由盆地向岩相的突然偏移所定义的层序边界所分隔，并且与先前在瓦迪阿尔希坦地区认识到的切谷的底部相等。这个边界可能等于早Priabonian Pr-2全球海平面下降。基于海相的海相堆积，上部单元的地层被解释为河口而非三角洲系统。