The Qatar–South Fars Arch Development (Arabian Platform, Persian Gulf): Insights from Seismic Interpretation and Analogue Modelling

The Qatar–South Fars Arch is a major regional anticline that runs through the central Persian Gulf (figure 1), warping the sedimentary cover of the Arabian Platform. The structure is detectable from offshore seismic data in the Iranian sector of the Persian Gulf, where it has a northeast–southwest direction, and extends southwards into the Qatar peninsula. Offshore, the arch hosts the biggest gas and condensate field in the world (South Pars–North Field), which straddles Iranian and Qatari waters. The Qatar–South Fars Arch represents a first-order structure and separates the Persian Gulf basin into two areas characterized by significant Proterozoic Hormuz salt diapirism (Northern and Southern Gulf Salt Basins, figure 1). The reported absence of salt-related phenomena on its crest led the authors to consider it as cored by an Infracambrian basement horst block, initiated during the Infracambrian Najd rifting, and repeatedly reactivated during subsequent geological time (Al-Husseini, 2000; Konert et al., 2001; Edgell, 1996; Talbot & Alavi, 1996). Although basement tectonics in response to geodynamic events is considered the main cause of the deformations associated with basement-cored structures in the Arabian Platform, the development history of the Qatar–South Fars Arch may not fit neatly into this scenario. Its continuous growth and extension, which is about one order of magnitude greater than the other north–south trending “Arabian structures”, the absence of major faults bounding the structure that actually encompasses several salt diapirs, and its northnortheast trend poorly matching with possible compressional and extensional reactivations that acted in a northeast-southwest direction point to a more complex origin for this intracratonic regional deformation. In this paper, the interpretation of a grid of 2D seismic lines crossing the Qatar–South Fars Arch axis in the Iranian sector of the Central Persian Gulf allows the study of a regional geological section perpendicular to the arch and the reconstruction of a structural map of the area, with the aim of defining the deformation history of this structure. Considering the widespread and long-lasting Hormuz salt tectonics in the neighbourhood of the Qatar–