Stratigraical studies on the Upper Cretaceous - Lower Eocenerocks in Central Eastern Desert, Egypt

Abstract

An attempt has been made to construct the lithostratigraphic and biostratigraphiccharacters of the Upper Cretaceous-Lower Eocene rocks exposed at Gebel Duwi andGebel Atshan sections, central Eastern Desert. Lithostratigraphically, the studiedsuccession arerepresented by four rock units arranged from base to top as: Dakhla,Tarawan, Esna and Thebes formations.Detailed study of planktonic foraminifera and calcareous nannofossils has led tothe recognition of forty five calcareous nannofossil and thirty one planktonicforaminiferal species. Twelve planktonic foraminiferal biozones, Racemiguembelinafructicosa Subzone (CF4), Pseudoguembelina hariaensis Subzone (CF3),Pseudoguembelina palpebra Subzone (CF2), Parasubbotina pseudobulloides Subzone(P1a), Praemurica uncinata Zone (P2), Morozovella angulata Zone (P3, subdividedintoIgorina pusilla Subzone P3a and Igorina albeari Subzone P3b), Globanomalinapseudomenardii Zone (P4), Morozovella velascoensis Zone (P5), Acarinina sibaiyaensisZone (E1), Pseudohastigerina wilcoxensis-Morozovella velascoensis Zone (E2),Morozovella marginodentata Zone (E3) and Morozovella Formosa Zone (E4) have beenrecognized as well as twelve calcareous nannofossil biozones; Micula murus Subzone(CC25c), Micula prinsii Subzone (CC26b), Cruciplacolithus tenuis Zone (NP2),Ellipsolithus macellus Zone (NP4), Fasciculithus tympaniformis Zone (NP5), Heliolithuskleinpellii Zone (NP6), Discoastermohleri Zone (NP7/ NP8), Discoaster multiradiatusZone (NP9), Tribrachiatus contortus Zone (NP10) and Discoaster binodosus Zone(NP11).The Cretaceous/Paleogene (K/Pg) boundary is marked by the absence ofnannoplankton NP1 Zone and the planktonic (P0 and P1 Zones). The K/Pg boundary islocated at the top of CC26b. This boundary lies in the middle part of the DakhlaFormation. The Danian/Selandian boundary can be placed inthe uppermost part of ZoneNP4 and nearly at the top of P3a Subzone in the upper part of the Dakhla Formation. TheSelandian/Thanetian boundary can be drawn at NP6/ NP7/8 zonal boundary, and theupper part of P4 Subzone within the Esna Formation. The Paleocene/Eocene (P/E)