THE MIOCENE CARBONATE ROCKS OF GEBEL QABALIAT (SINAI PENINSULA): PETROGRAPHY, GEOCHEMICAL CHARACTERISTICS AND DEPOSITIONAL ENVIRONMENTS. MOHAMED A.K. BARAKAT(1), AMRE M.EL-GOHARY(2) and SAMIA EL-WEKIEL(2) (1) Exploration Dept., Egyptian Petroleum Research Institute. Nasr City, Cairo, Egypt. (2) Geological and Geophysical Sciences Dept., National Research Center, El- Dokki, Cairo. Egypt. The Miocene carbonates of Gebel Qabaliat are generally composed of white, yellow, pink or reddish limestones which are hard, massive and highly fossiliferous, they pass into conglomeratic sandstones and limestones near the top of the section, and is capped by post-Miocene sands and gravels. Three microfacies are distinguished in the present study indicating deposition in shallow - marine conditions. The main diagenetic processes which affected these rocks are neomorphism, fracture and cavity filling, cementation, silicification, dolomitization and halite precipitation. Geochemical analyses showed depletion in the Mg, Ni, Cr and V-contents. The strong positive correlation between SiO2 and AIR indicated that AIR of the studied carbonates consists mainly of quartz grains. NaCl represents the main soluble salt in the Gebel Qabaliat carbonates. The isotopic composition of the studied Miocene carbonates indicates that they were mainly deposited in marine environment and the diagenetic processes occurred in fresh-water meteoric environment.