Cretaceous sequence of deformation in the SE Zagros fold–thrust belt

Abstract

Several major zones across the Zagros fold–thrust belt have been interpreted as indicating that orogeny took place progressively from NE to SW through discrete orogenic episodes during Tertiary time. This paper uses field evidence of growth onlaps and angular unconformities within the Cretaceous stratigraphic column as well as existing geological maps and cross-sections to indicate that deformation started as early as the Late Aptian and folded the whole width of the Zagros belt simultaneously. Later events are indicated by folding at the end of the Cenomanian, and in the Late Turonian and Santonian. Following the Late Cretaceous deformation phases, the SE Zagros basin was divided into several longitudinal intra-shelf basins, which were separated by NW–SE-trending Cretaceous anticlines. However, with reference to our previous work, it can be suggested that each of the sub-basins was folded serially from NE to SW through a series of tectonic phases during the next episode of Zagros orogeny in Tertiary time. The change of deformation style from concomitant to serial folding, during the Cretaceous and Tertiary respectively, is attributed to the existence of the Hormuz Salt and shearing at the base of the former basin and its absence at the base of the Tertiary intra-shelf basins.