Planktonic and larger foraminifera from the Upper Paleocene and Lower Eocene of Gebel Gurnah, Luxor, Egypt

Abstract

In the Upper Paleocene - Lower Eocene succession of Gebel Gurnah two formationa are recognised which are separated bY a minor disconformity. The Owaina Formation of Upper Paleocene age is represented by the topmost part of the Upper Owaina-Shale Member. The Thebes Formation of Lover Eocene age is represented by a lower Thebes Calcareous Shale Member and an upper Thebes Limestone Member. The detailed study of the planktonic Foraminifera has led to the description of ninety species, subspecies and varieties; thirteen species and subspecies of which are new. The planktonic foraminiferal genera Guembelitrin, Chiloguembelina and Globanomalina are described for the first time in this locality. Six planktonic foraminiferal zones are recognised in the present sequence. The Globorotalia velascoensis zone is of Upper Paleocene age and coincides with the Upper Owaina Shale Member. The Globorotalia aequa, G. subbotinae, G. formasoformosa, G. aragonensis and G, "palmerae" zones are of Lower Eocene age and coincide with Thebes Formation. The detailed study of the planktonic Foraminifera with the six zones established in the present succession make an excellent basis for inter-regional and inter-continental correlation with similar planktonic zonations in many parts of the world. A careful study of the larger fossil Foraminifera has also been carried out. Nine species, subspecies and one variety are described. One species and one variety of the genus Operculina are described as new. The larger fossil Foraminifera are restricted to Rock Units IV and V of the Thebes Limestone Member. A numerical analysis of the foraminiferal population in the lower shaly part of the succession has led to a number of very important conclusions concerning frequency in relation to sediment and ratios of selected taxa.