Document Type : Research Paper
Department of Geology, Faculty of Basic Sciences, University of Hormozgan, Bandar Abbas, Iran
PH.D., National Iranian Oil Company, Exploration Directorate, Department of Surface Geology, Tehran, Iran
Sedimentary successions in the eastern part of the Zagros Fold-Thrust Belt were episodically influenced by halokinetic events. The positive and negative accommodation spaces created by salt-induced uplifting and downbuilding processes caused variable sedimentation rates followed by stratal geometry variations and forming the halokinetic sequences. The Handun passive salt diapir, located in the north of the Bandar Abbas area is one of the best examples in which the evolution of the salt diapir could be analysed by the halokinetic sequences. These sequences are studied in four outcrop sections in the core of Handun anticline within the uppermost part of the Cretaceous to Lower Cenozoic successions (Tarbur Formation to Guri Member of the Mishan Formation). The succession flanking of salt diapir displays various halokinetic sequences with hook and wedge types growth strata. These geometries are mainly developed in the Paleocene-Eocene Pabdeh and Jahrum Formations. The Middle-Upper Eocene Jahrum Formation shows the maximum facies, geometry, and thickness variations and is truncated by a regional unconformity at the Eocene-Oligocene boundary. This stratigraphic unit is also interrupted by an allochthonous salt sheet as a result of lateral extrusion of the Hormuz salt. In addition, withdrawal and uplifting of the salt diapir caused strong lateral changes in accommodation spaces and sedimentation rates during this time interval. These variations could be documented by hook geometries in the halokinetic sequences around the Handun salt diapir. During the Oligocene to Lower Miocene times, in the Razak Formation and lower parts of the Guri Member, hook types growth strata can be observed in the N flank of the Handun salt diapir, while in other flanks, geometries of the sequence/growth strata become wedge-shaped more tabular far from the salt diapir. Based on these variations three halokinetic phases have been recognised which include nine halokinetic sequences showing the temporal and spatial effects of the halokinesis on the sedimentation systems.