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Chapter 2 Structural development of the Arabian Intrashelf Basin region

Abstract This chapter summarizes the tectonic events that have affected the region of the Arabian Intrashelf Basin and the development of the intrashelf basin. Precambrian–Infracambrian fault systems provided a structural framework, which was later reactivated during the Late Paleozoic. Further development along the structural trends continued in the Triassic and Early Jurassic with the development of an Early Jurassic tectonically controlled intrashelf basin. The accommodation space was filled with Dhruma Formation carbonates by the early Bathonian, resulting in a broad and fairly flat platform. A crucial factor is how suppressed tectonism was during the Mid- and Late Jurassic. The intrashelf basin developed on the broad, tectonically stable Tethyan passive margin continental shelf 200--300 km distant from the Tethyan outer shelf edge. During the Mid- and Late Jurassic, this tectonic stability provided the foundation for a broad, stable Tethyan continental shelf region at least 1000 × 1200 km in area, far removed from siliciclastic sources, within which the huge Arabian Intrashelf Basin formed and the sequences of carbonate rocks and evaporites that created the Jurassic hydrocarbon system were deposited. Tectonism during the Mid- to Late Jurassic evolution of the Arabian Intrashelf Basin initially included only moderate subsidence. There was subtle uplift along some of the structural trends in the Late Jurassic and uplift and westwards structural tilt along the Tethys oceanic margin. Relatively stable tectonism continued after the Jurassic and was a major factor in the accumulation of the vast reserves of Jurassic sourced oil. Tectonic stability prevented major faulting and structural compartmentalization of the basin features, which provided large areas for hydrocarbon migration as the large and broad anticlines developed into the huge structural traps. The lack of major faulting limited the movement of burial fluids, preserving the early formed porosity and the regionally extensive seals. The present day structures primarily developed from the Late Cretaceous to Miocene as the Tethys Ocean closed.