CONTRIBUTIONS TO SEDIMENTOLOGY OF CRETACEOUS ROCKS, GABAL ELMINSHERAH AREA, NORTH CENTRAL SINAI, EGYPT OMAR A. HEGAB, ADEL A. ELHABAB, and MOHAMED O. ALI1 Dept. Geology, Fac. Sciences, Mansoura Univ., 1Dept. Science & Math. , Fac. Petroleum & Min., Engeering, Suez Canal Univ., Egypt. The Cretaceous sediments of North Central Sinai are well exposed at Gabal ElMinsherah. Samples of these sediments are studied for the lithostratigraphy, microfacies, depositional environments and diagenesis. The lithostratigraphic study allowed differentiating five rock units from base to top; Malha, Halal, Wata, Themed Formations and Sudr Chalk. Sixteen microfacies were identified in these rock units: Ferrugineous quartz arenite and quartz wacke (Malha Fm), sandy biomicrite, dolostone, subarkosic arenite and biomicrite (Halal Fm), dolomitizcd biomicrite, dolostone and biomicrite (Wata Fm), Ostracodal biomicrosparite, foraminiferal biomicrite, dolostone and phosphatic foraminiferal biosparite (Themed Fm), fossiliferous micrite, foraminiferal biomicrite and phosphatic foraminiferal biomicrite (Sudr Chalk). Diagenetic processes that affected the Cretaceous units include recrystallization, ferrugination, dolomitization, textural inversion and grumeleuse texture. The lithic characters and microfacies interpretation indicate that the Malha Fm was deposited in continental fluviatile environment, Halal Fm in inner shelf (shelf lagoon and shoal), Wata Fm deposited in shelf lagoon to fore-reef slope with open circulation at the wave base, Themed Fm in inner shelf (winnowed platform to deep marine), and the Sudr Chalk was deposited in deep marine environment.