Thicknesses of Sedimentary Sequences in Abu Dhabi: Implications for Tectonic and Stratigraphic Evolution of the Basin

Abstract

The Abu Dhabi Emirate is located on the northeastern margin of the Arabian Plate. It encountered uplift and subsidence episodes that allowed the deposition of thick sedimentary successions and the development of thrust and fold sheets that form today's most valuable oil and gas fields. This study aims to use 32 2D seismic profiles, 323 exploratory wells, and modern basin analysis techniques to determine the stratigraphic thicknesses of the successions deposited from the Permian to the Neogene and to understand the depositional settings and the tectonic driving forces resulting in thickness variations. Seismic interpretation provided structural surfaces and thickness maps. In addition, backstripping of biostratigraphic data was used to perform subsidence and uplift analysis. The study provides a greater understanding of the tectonic history and depositional environments that created the Abu Dhabi succession. As a result, four main sequences were identified: The Mesozoic passive margin sequence, the Late Cretaceous Aruma foreland basin sequence, the Maastrichtian to Eocene sequence, and the Oligocene-Miocene sequence. The results of the backstripping suggest two rifting phases (1) Late Permian to Late Triassic rifting phase (260-235 Ma) and (2) Early Jurassic to Late Cretaceous rifting phase (200-120 Ma). These rifting episodes are followed by uplift and subsidence during Late Triassic to Early Jurassic uplift (235-175 Ma) and Late Cretaceous uplift and subsidence (90-70 Ma) and Paleogene-Neogene uplift and subsidence (25-15 Ma). The stretching factor varies across wells and rifting phases, with a range of 1.08-1.33 for the initial phase and 1.12-1.15 for the final phase that resulted in a crustal thinning of approximately 27.5 km from the initial thickness of 31.2. The depth and thickness maps suggest overall succession depth and thickness increase to the east direction as a result of the formation of the Aruma foreland basin. Moreover, these sequences show a regional scale thinning and thickening and the occurrence of unconformities that can be linked to the Arabian Plate's tectonic evolution.

Date of Award	Aug 2023
Original language	American English
Supervisor	Mohammed Ali (Supervisor)