Log correlations, biostratigraphical results and seismic data were combined to show that from Late Triassic Norian to Early Cretaceous Aptian times, the Euphrates area (Eastern Syria) was part of a huge saddle-like northeast-trending ridge (the Hamad Uplift) characterized by a prolonged stratigraphic hiatus. This uplift, developed in the Late Triassic, was multiply reactivated during the Mesozoic, particularly in the Early Cretaceous Aptian-Albian times, during a major reorganization phase of the Neo-Tethyan rift system. This uplift marked the separation between two regions with distinctive tectono-sedimentary evolutions: an eastern isolated and starved region (Euphrates Graben) and a western region that was mainly influenced by the sedimentary dynamics of the westerly Bishri Trough, linked to the Palmyrides Basin. The Hamad Uplift broke-up into a N140°E-oriented graben system in late Albian times. This early NE-trending extensional stage was accompanied by volcanic activity and introduced the main phase of horst-and-graben development within the Euphrates Graben in the Late Cretaceous Senonian times.