The present study deals with the stratigraphy, petrography and facies analysis of the stratigraphic succession of
Mitla-El Giddi stretches (west Central Sinai, Egypt). Lithostratigraphically, the study area is covered by a thick
succession extending from Late Jurassic to early Eocene time. This succession is subdivided into the Masajid
Formation (Upper Jurassic (Oxfordian) at the base followed upwardly by the Risan Aneiza Formation (Lower
Cretaceous (? Aptian- Albian), the Galala Fm. (Cenomanian), the Abu Qada Formation (lower Turonian), the
Buttum Formation (middle Turonian), the Wata Formation (middle–upper Turonian), the Themed Formation
(Coniacian–Santonian), the Sudr Chalk (Campanian–Maastrichtian), the Mitla Formation (= Esna Shale)
(Paleocene–lower Eocene), the Thebes Formation (lower Ypresian) and the Minia Formation (upper Ypresian) at
top. The Aptian – Albian Risan Aneiza Formation is first recorded at G. El Hamra in the study area. As well, a new
formational name (the Mitla Formation) is used to describe the Paleocene – lower Eocene unit equivalent to the
Esna Shale due to variation in lithology mainly represented by chalky limestone and argillaceous limestone.
Many unconformities, represented by variable sedimentologic features, i.e., red paleosols, conglomerates,
crustified laminated limestone and glauconitic facies were investigated and mostly attributed to the Syrian Arc
System.
The petrographic investigations especially for the lithified rocks revealed eighteen limestone microfacies,
three dolostone microfacies and four sandstone microfacies, besides the non-lithified shale, sandy shale, clay and
marl lithofacies. The recognized facies and their related paleoenvironments document lateral and common
vertical transition between inner, middle and outer ramp setting. These facies could be subdivided into eight
associations that are related to six depositional environments: peritidal flat/beach clastics, peritidal flat carbonates,
lagoonal clastics, lagoonal carbonates, high energy shoal of ooids and patch reefs (oolitic shoal), intertidal-
subtidal open marine, storm influenced subtidal open marine (mid-ramp) and hemipelagic outer ramp
facies.
The study indicates that, the area was controlled by a long-term transgressive phase and several higher order
sea level fluctuations during the deposition of the studied succession. The main factors controlling the ramp
deposition and the described events are; structure control mainly Syrian Arc deformation, eustatic sea level
fluctuations combined with environmental influences such as autochthonous carbonate productivity-siliciclastic
supply and paleorelief conditions. |
