Journal of Petroleum Geology, zyxwv 12(3), July, 1989, pp. 253-288. 253 PETROLEUM GEOLOGY OF THE UNITED ARAB EMIRATES A. S. Alsharhan* zyxw The Permian to Holocene sediments of the UnitedArab Emirates consist mainly of epeiric shelf carbonates, associated with minor clastics and evaporites, reflecting major cycles of transgression and regression. These were deposited on the eastern maqin of the Arabian Shield, which lay along the southern margin of the Tethys Ocean during the Mesozoic-Cenozoic eras. Sedimentation patterns were controlled by prominent regional structural features, epeirogenic movements and/or sea-levelfluctuations. The tectonic history of the UAE in the Mesozoic-Cenozoic is connected with the opening (Triassic)and closure (Upper Cretaceous-Paleogene)of the southern Neo-Tethys Ocean. The distinctive structural style, together with the tripartite development of source-reservoir-seal, has produced in the UAE one of the world's richest Jurassic zyxw - Cretaceous oil habitats. Significant oil discoveries have also been made in the Permian: Middle and Upper Jurassic; Lower- Middle-Upper Cretaceous and Oligo-Miocene carbonates. Two main source rocks have been identified. One is the Upper Jurassic Diyab/Dukhan Formation, which supplies the most prolific reservoirs in the Upper Jurassic (Arab Formation) and Lower Cretaceous (Thamama Group). The other is the Middle Cretaceous Shilaif/Khatiyah Formation, which feeds both Mishrif and Simsima reservoirs. Other minor potential source rocks have also been identified in the study area. There are two principal sealing formations - the Hith Anhydrite and the Nahr Umr shale: these are the main seals for the oil and gas accumulations in the underlying Arab Formation and Thamama Group, respectively. Secondary seals and barriers also exist in the stratigraphic sequence. INTRODUCTION zyxw The UAE is located in the eastern part of the Arabian Peninsula, between latitudes 22" z 40' and 26" zyxwvut 00', and longitudes 51" 00' and 56" 00'. In terms of tectonic framework, the UAE is situated within the interior platform of the Arabian shelf, bounded on the NW by the Qatar - South Fars Arch, and on the east and NE by the foreland basin, and adjacent foreland fold and thrust belt, of Oman (Fig. 1). Two passive plate margin basins were developed in the area - the Rub a1 Khali and Ras al Khaimah Basins. The.Permian - Recent sequence here is dominated by marine carbonates, with occurrences of terrigenous clastics and evaporites associated with cyclic periods of marine regression. *Geology Department, UAE University, PO Box zyxw 15551. AI-Ain, United Arab Emirates.