Salt tectonism in the Persian Gulf Basin

Abstract

The Persian Gulf Basin is an elongate, margin sag-interior sag, sedimentary basin spanning the last 650 Ma along the northeastern subducting margin of the Arabian Plate and is the largest basin with active salt tectonism in the world. This basin is asymmetrical in NE-SW cross section with sediments thickening from 4,500 m near the Arabian Shield to 18,000 m beside the Main Zagros Reverse Fault. Halokinesis in the Persian Gulf Basin originates where major intersecting basement faults cut the buoyant salt beds of the Neoproterozoic Hormuz Series (1.5 to 2.5 km thick) and the equivalent Ara Formation of Oman where salt thickness reaches 4 km. Another source of salt is the Oligo-Miocene Gachsaran Formation, forming Lali salt plug. Major basement fault trends control salt tectonism in the basin, namely the extensional N-S Arabian Trend, the sinistral NE-SW Aulitic Trend, the dextral Erythaean Trend and the extensional E-W Tethyan Trend. The main types of salt structures in the Persian Gulf Basin are salt domes, salt pillows, salt walls, salt piercements, rim anticlines, turtleback structures, disharmonie folds, orogenic fold fillings and dissolution drapes. Diapiric oil fields, account for 60% of the 600 billion barrels of recoverable oil reserves of the Persian Gulf Basin and have grown continuously since Late Jurassic, or since Permian in some large structures, such as Bahrain.