Structural framework of the Zagros Fold-Thrust Belt, Iran

Data gleaned from the literature on the Zagros have been compiled and used in conjunction with new interpretations to provide a better picture of the structures, sedimentation history and deformation of this hydrocarbon rich Mountain Belt. The belt parallel Mountain Front, the N-S trending Kazerun, Izeh and E-W trending Bala Rud Fault Zones are defined as the master structural elements of the Belt. These fault zones divide the Zagros basin into zones with different stratigraphic successions and different rheological profiles. This resulted in different structural styles developing along the belt during the subsequent collision. The Kazerun and Izeh Fault Zones acted as the depositional system transition zone between the Lurestan and Fars regions in Jurassic-Cretaceous time and partly controlled the distribution of the Kazhdumi Formation (one of the major source rocks). By the end of the Cretaceous the NW-SE trending Mountain Front Fault divided the present Folded Belt of the Zagros into a major foreland basin to the southwest, and a piggyback basin to the northeast. Activity along other major (transfer) fault zones including the Izeh, Kazerun and Bala Rud Fault zones occurred at this time and controlled the sedimentation and subsidence of the Dezful Embayment the main target region for hydrocarbon exploration. These fault zones controlled the thickness of the Asmari Formation (one of the main reservoirs) and also the considerable thickness and facies changes of the Gachsaran Formation (the major seal to the Asmari Formation). The present morphology of the mountain belt is interpreted as being mainly related to the pinning of the Mountain Front Fault to the northwest of the Dezful Embayment and to the north of the Strait of Hormuz. (C) 2004 Elsevier Ltd. All rights reserved.