Seismic stratigraphy and subsidence history of the United Arab Emirates (UAE) rifted margin and overlying foreland basins

Abstract

Regional seismic reflection profiles and deep exploratory well data have been used to determine the structure and evolution of the United Arab Emirates (UAE) rifted margin and overlying foreland basins. We recognized three major tectonostratigraphic sequences in the seismic profiles. A lower rifted margin sequence which is characterised by an early syn-rift sequence of mainly Late Permian age that is overlain by a post-rift sequence of Triassic-Jurassic to Late Cretaceous age, and an upper foreland basin sequences of Aruma (Late Cretaceous) and Pabdeh (Palaeocene—Oligocene) Groups. Backstripping of the well data provides new constraints on the age of rifting, the amount of crustal and mantle extension, and the development of the UAE rifted margin and foreland basins. The tectonic subsidence and uplift history at the wells can be explained by a uniform extension model with at least two episodes of rifting punctuated by periods of relative tectonic quiescence and thermal subsidence. An initial age of rifting of 260 Ma and a stretching factor, β, of 1.2 was followed by second period of stretching with an initial age of rifting of 180 Ma, and β, of 1.1. This model accounts for the general exponential decrease observed in the backstripped tectonic subsidence. The model, fails, however, to completely explain the slow subsidence and uplift history of the margin during Late Triassic to Early Jurassic. We attribute this slow subsidence to combine effect of a sea-level fall and regional uplift which caused major unconformity particularly offshore western Abu Dhabi. The backstrip curves suggest that the transition from an extensional rifted margin to a compressional foreland basin occurred at ~90 Ma, which is within the range for the emplacement of the Semail Ophiolite (95–68 Ma). The history during this time is characterised by uplift followed by rapid subsidence. We attribute these differential vertical movements to orogenic loading and flexure of the Arabian rifted margin by the Semail Ophiolite and development of Aruma foreland basin.