Facial Evolution and Petroleum Potential of the Uppper Cretaceous Black Shales of Southeast Egypt

Herwig Ganz, Peter Luger, Eckhart Schrank, Paul W. Brooks, Martin G. Fowler

Newly developed and conventional organic and inorganic geochemical and sedimentological techniques and facies parameters resulted in the reconstruction of the depositional environment and an estimation of the resource potential of the upper Cretaceous black shale/phosphorite sequences in southeastern Egypt. The depositional environment is characterized by a broad, shallow shelf which was separated from the continental hinterland by restricted coastal swamps. Depending on structures on the sea floor and depth of the water column, reducing conditions prevailed. The Campanian/Maastrichtian transgression was interrupted by multiple regressive phases which caused intensive reworking of the marine sediments and the enrichment of phosphatic layers. Minor terrestrial influx occurred during th formation of oyster reefs. Open marine conditions in the upper part of the section (Dakhla Shale) indicate prograding marine transgression.

The composition of the black shales is very heterogeneous. Generally the beds which yield a high energy potential (up to 6,000 kJ/kg) are only isolated thin layers. However, the average values of a 40-m Dakhla Shale profile indicate that this sediment is an immature, potentially good source rock for oil and might be suited as a raw material for energy and cement production. Since the average trace element contents in the Dakhla Shale are rather low, final leaching of the combustion residue is not worthwhile.

AAPG Search and Discovery Article #91032©1988 Mediterranean Basins Conference and Exhibition, Nice, France, 25-28 September 1988.