The Quaternary sediments outcropping along Egyptian coast of the Red Sea area are represented by a series of terraces including a sequence of mixed siliciclastics, reefal carbonates and evaporites.
In addition to sea level changes and climatic conditions, two main factors caused the rapid facies variations of these sediments. These are the easterly trending tectonically-controlled wadis and fractures and the post Pliocene tectonic framework composed of NW block-faulting and folds, resulting in depressions and highs. The reaction of these factors resulted in the formation of three models of deposition:
A- In the first model, the Pliocene sediments werse downfaulted forming a relatively broad NW trending depressions bounded by faults trending N140 and N40-60. In this case the pleistocene sea extended westward. Rapid lateral transitions between siliciclastics and reefal carbonates characterise the sediments of this model
2- In the second model. the Pliocene sediments were folded resulting a series of depressions (synclinal troughs) and highs (anticlinal crests). Dominantly carbonate reefal flat and slope facies were deposited over highs, and intermixed fan-reef associations in the depressions.
C- In the third model, the Pliocene and older sediments were block-faulted forming NW trending depressions and highs. Dominantly continental siliciclastics and carbonates were laid down in the inland depressions and highs to the west, while reefs and mixed fan-reef associations are deposited in areas closer to the sea.
By the end of pleistocene, rejuvination of NW and ENE faults associated with severe erosion, took place. This resulted in the formation of new highs and lows. Subsequently, the Holocene transgression caused the accumulation of fringing reefs on the highs and mixed siliciclastic-evaporites in the depressions.