Based on geographic distribution and geological setting of salt plugs in southern Iran, three salt diapiric provinces have been distinguished. These provinces include the Hormuz, Shiraz-Kazerun and Nyriz-Jahrum sub-basins. There are more than hundred salt plugs which they have been formed and developed in the southern margin of Iran. The salt structures that originated from Hormuz formation in these areas have been restricted and separated from each other for the first time in this paper. Salt diapirism of these provinces has been triggered earlier by Halokinesis in the Zagros and Persian Gulf basins, but it has affected later by tectonic forces, because orientation, shape and position of salt plugs have been followed from convergence regime (especially in the Zagros hinterland). In the other hand, based on our results from salt plugs in Persian Gulf foreland basin and the Zagros hinterland, Halokinesis triggers has been affected more than Halotectonic forces.
The purpose of this research is clustering of salt plugs in the southern margin of Iran such as central Iran that it has worked by [
The structural trends in Zagros province are north west-south east. It contains the fold and thrust belt that formed on the northeastern margin of Arabian plate [
More than 100 emergent salt structures, up to now, have been recognized in the Zagros mountain and Persian Gulf areas [
Hormuz Salt had been deposited within N-S and NW-SE trending troughs of the Arabian Basement in Late Precambrian-Early Cambrian. Also, Presence of Hormuz Salt in the western part of the Zagros Belt including the Abadan Plain is almost possible by geophysical data. Analysis of gravity data denotes negative anomalies beneath the structural highs. Also, seismic data are presenting additional evidences for upward movement of the Hormuz Salt which affected deposition of the younger sediments. Anticline structures of the Abadan Plain are formed above strike-slip fault systems. Salt walls or salt anticlines are probably emplacing core of the N-S trending structures. Upward movement of salt is due to curvature and step over along the strike-slip fault system and transtension [
The name of the Hormuz salt was taken from the Iranian Hormuz Island, cored by a salt diapir, which also gives its name to the opening strait of the Persian Gulf. The Hormuz formation [
Coeval salt basins crop out in a large domain including the eastern Zagros, Persian Gulf, Oman, Qatar, Central Iran, Pakistan, and northwest India [
The age of salt diapirism of Hormuz in the Zagros orogeny belt is very different and it has investigated by many workers such as [
This condition has confirmed by later researches such as [
The Zagros orogenic belt is a result of the Neogene collision between the Arabian and Cimmerian plates [
The sedimentary succession in the Zagros is 6 - 18 km thick and ranges in age from Infra-Cambrian to Recent. There is a break up unconformity (the absence of Silurian and Carboniferous sediments) that is appropriate with [
The northeastern part of Afro-Arabian plate margin began to undergo regional extension in the Infra-Cambrian to Carboniferous, finally caused to appear of a narrow oceanic basin between the Afro-Arabian plate and Cimmerian miniplate (Neo-Tethys) from the Carboniferous.
Then, post-rifting facies of passive margin from early Permian to the late Cretaceous were deposited on the Zagros basin. Since the late Jurassic, the Neo-Tethys ocean began subduction under the Cimmerian miniplate. A proforeland basin [
Salt diapirs of Zagros present a large variety of shapes and elevation from high relief to entirely eroded structures. In addition, they have different sizes at outcrop scale, ranging from craters a few km wide to diapirs and glaciers more than 5 km wide. These different morphologies are controlled by various factors, for example, position related to other structures, the time of emergence, the rate of salt dissolution, which is controlled by the rate of erosion, the bulk rate of salt emission from the source layer, and eventually by the tectonic activity [
The Salt plugs of the southern Iran can be divided into four areas, based on geographic distribution and geological setting of salt plugs (
1) The first area is central Zagros, with 23 emergent salt plugs.
2) The second area is southeastern part of Zagros, with 84 emergent salt plugs.
3) The third area is north margin of Persian Gulf, with 10 emergent salt plugs such as Hormuz, Larak and Abu Musa Islands.
4) The fourth area is an area between the first and second region in Zagros, with many subsurface salt plugs.
There are three diapiric provinces have distinguished (
The diapiric province of Hormuz, in the east end of Zagros, with eighty four exposed salt diapirs is the widespread salt depotrough in Zagros. Because, based on previous studies, such as [
Therefore, only some of salt diapirs have been exposed in post-orogenic phase, and their shape and location have controlled by folds and faults interactions during orogeny (
The diapiric province of Nyriz-Jahrum, in the centrral Zagros is a small salt minibasin. It has got a few exposed salt diapirs, many blind domes such as Sim, Meymand, Bavush, Kharman (
The Gavbandi High [
The diapiric province of Shiraz-Kazerun is located in the west part of Nyriz-Jahrum diapiric province .It has got twenty three exposed salt diapirs and its area is smaller than Hormuz diapiric province.
The main north-south striking right-lateral faults in Zagros have been controlled location of this salt diapirs such as Kazerun fault with six, Kareh Bas fault [
However, based on previous study [
affected by rift development during Paleozoic that it has accompanied with sedimentation of Banded Iron Formation (BIF) in Hormuz Group (
Finally, based on previous work on the neotectonic regime in Iran, Zagros in south Iran is the most active zone [
According to our results on the geographic distribution and geological setting of salt plugs in southern Iran, three salt diapiric provinces have been distinguished. These provinces include the Hormuz, Shiraz-Kazerun and Nyriz-Jahrum sub-basins.
Hormuz Salt is a member of the bigger rock unit (Super-group or Group) that, it had been deposited within syn-rift basins of the Arabian basement in Late Proterozoic-Ordovician.
Salt diapirism of these provinces has affected later by tectonic forces (especially in the Zagros hinterland which it has been recorded in orientation, shape and position of salt plugs), although it has been triggered earlier by Halokinesis in the Zagros and Persian Gulf basins. Also, extentional phase of Neo-Tethys rifting at early Paleozoic should be considered as the most important salt diapirism in the southern Iran. This rifting has been an important role on genesis of Banded Iron Formation that introduced in this paper at the first time.
The most of salt plugs are pre-orogenic emergent diapirs, thus they had got essential role in formation and development of the next structures during the Zagros deformation. However, progressive deformation has got an additional affects to reactivation of salt plugs.
The authors acknowledge department of geology, Islamic Azad University, Science and Research branch, Tehran, Iran for funded this project. In addition, we thank Vice-President for Research in Science and Research branch, Tehran.
Azar Khodabakhshnezhad,Mehran Arian, (2016) Salt Tectonics in the Southern Iran. International Journal of Geosciences,07,367-377. doi: 10.4236/ijg.2016.73029