Litho- and biostratigraphy of the Lower Eocene carbonate sequence in Upper Egypt: evidence for uplifting and resedimentation of the Paleocene section

Abstract

The Lower Eocene carbonate succession outcropping east of Qena and Sohag, Upper Egypt is divided into the thebes and Drunka Formations. Field observations and petrographic analysis demonstrated interfingering relationship between these units. Moreover, the Assiuti Chalk and Manfalut Formations of Bishay (1961, 1966) as well as the Thebes Formation of Said (1961) are considered here unique lithostratigraphic unit. Biostratigraphically, the Lower Eocene carbonates are subdivided into two larger foraminiferal zones: (1) Nummulites solitarius (discocyclina irregularis/Operculina libyca) Zone (Early Ypresian) and (2) Nummulites planulatus/N. burdigalensis Zone (Late Ypresian) besides three algal zones of Late Ypresian age: (1) Ovulites maillolensis Zone followed upward by (2) Carpathoporella occidentalis Zone and (3) Belzungia borneti Zone. These faunla and floral zones are correlated and all the identified larger foraminifera (nummulites, discocyclines and operculines) and calcareous green algae (dasycladacean and codiacean) are point counted as well as their vertical distribution in six measured columnar sections are represented. Here, for the first time, coexistence of mixed Paleocene reworked planktonic foraminifers with the Ypressian sediments is recorded in the Thebes Formation. Therefore, we suggest that the Paleocene sequence in Egypt may have been subjected to uplifting and subaerial exposure followed by severe denudation during the Ypresian time.