TECTONIC IMPLICATIONS OF DIAPIRISM ON HYDROCARBON ACCUMULATION IN THEUNITED-ARAB-EMIRATES

The offshore of the United Arab Emirates (U.A.E.) contains eight diapi ric islands; Dalma, Zirkouh, Qarnain, Das, Sir Bani Yas, Arzana, Sir A bu Nuwair and Abu Musa. These islands and Jebel Dhanna Peninsula owe t heir relief to the diapiric movement of salt which has pierced and def ormed the overlaying strata. These diapiric islands have similar shape s, stratigraphic sequences, areal distribution of the identified strat igraphic units and general tectonic framework. With the exception of D as Island, the stratigraphic sequence on the surface of all the diapir ic islands consists, in ascending order, of: 1) Infracambrian to Cambr ian (Hormuz Group) composed of igneous and metamorphic rocks, salt, an hydrite, carbonate and elastic interbeds; 2) Miocene composed of sands tone, siltstone, shale, carbonate and evaporite interbeds; and, 3) Pli ocene to Recent sediments composed of mixed facies of clastics, carbon ates and evaporites. The structural configuration and the tectonic dev elopment of the Arabian Gulf Basin played an important role in the sal t movement, which enhanced the formation and distribution of the islan ds, the timing of hydrocarbon generation, migration, and entrapment in the surrounding fields. The U.A.E., one of the world's richest in oil reserves, has almost 200 billion barrels (Bbbl) of oil and 275 trilli on cubic feet (TCF) of gas that is sourced mainly from the Upper Juras sic and Lower to Middle Cretaceous formations and accumulated in carbo nate reservoirs that range in age from upper Paleozoic to Oligo-Miocen e. The geophysical and the geological data revealed three trap geneses in the U.A.E.: 1) Salt-related; 2) basement-related; and, 3) fold bel t (collision) traps. Salt-related oil fields of the U.A.E. offshore ar ea are characterized by: (a) dome-shaped structures; (b) independent c losures; (c) radial faults within the structures; and, (d) multi-step structural growth histories. Subtle turtle structures exist between th e diapiric islands of the U.A.E.. These structures form fields at Hair Dalma and Dalma, near Dalma Island, Mandous field, near Sir Abu Nuwai r Island, and Mubarek field near the Abu Musa Island. The quality of t he carbonate reservoir in the salt related oil fields is attributed to the effects of the diapiric salt movement.