Variation of subsidence in the Dezful Embayment, SW Iran: influence of reactivated basement structures

Abstract

Subsidence analyses over the past 140 Ma in 15 wells in the Dezful Embayment, which is the main oil-producing area in the Zagros fold and thrust belt, SW Iran, have significantly improved our understanding of the post-Jurassic evolution of the basin. A number of regional-scale tectonic events since the Early Cretaceous were separated by tectonically quiescence periods, which controlled the basin architecture of Central Zagros basin evolution. Subsidence patterns in the Dezful Embayment during tectonically active periods are evidence for the influence of the Precambrian basement tectonics on sedimentation and deformation. This study shows that basement paleo-highs in the Central Zagros are regional-scale features, which may be related to regional upwarps, and are not restricted to the reactivation of deep-seated faults. However, when deep-seated faults developed over regional basement highs, their impact on sedimentation could intensify and be easily recognized in seismic by truncation/onlap features. The impacts of subsidence variations in the Dezful Embayment to the deposition and maturation of the Albian source rock, and on the development of migration path ways for hydrocarbons, are discussed.