Implications of calcareous nannofossil biostratigraphy, biochronology, paleoecology, and sequence stratigraphy of the Paleocene-Eocene of the Wadi Qena, Egypt

Abstract

The depositional sequence stratigraphy examination of the Paleocene-Eocene succession in Wadi Qena has been carried out based on the quantitative analysis of the nannofossil assemblages. Based on the lithostratigraphy, biostratigraphy, paleoecologic parameters (relative abundance of calcareous nannofossil, diversity indices of nannfossil, life strategies of calcareous nannofossil, Total Organic Carbon (TOC) and Calcium carbonate (CaCo3%), the temperature index (TI) of calcareous nannofossil, productivity indicators of calcareous nannofossil and sedimentation rate (SR). We detected six nannofossil biozones in the Paleocene-Eocene succession from NP4 to NP10 zones. The Se/Th boundary can be found in the NP7/8 Zone of the Hawashiya succession and the lower part of the NP9 Zone of the Abu Had succession. The P/E boundary is placed in the upper part of the NP9 Zone in the Hawashiya succession, and in the Abu Had sections, it coincides with the NP9/NP10 zonal boundary. These sea level falls compete well with the eustatic sea level drops that are only found in the Paleogene and are linked to tectonic events. In all, five stratigraphic sequences were recognized in the studied area. The first depositional sequence A (DS A) occurs within the nannofossil NP4 zone in the lower part of the Dakhla Formation, the second depositional sequence B (DS B) occurs in Fasciculithus tympaniformis (NP5) Zone in the Dakhla Formation, the third depositional sequence C (DS C) occurs between Heliolithus kleinpelli (NP6) and the lower part of the Discoaster multiradiatus (NP9) Zone, the fourth depositional sequence D (DS D) falls within the interval of Discoaster multiradiatus (NP9) Zone. It covers the Upper Paleocene part of the Esna Formation at Hawashiya and Abu Had sections, the fifth depositional sequence E (DS E) within the interval of the Tribrachiatus contortus Zone (NP10). It covers the Early Eocene (Ypresian) part of the Esna Formation (El Shaghab member) at Hawashiya and Abu Had sections.