28

RESEARCH JOURNAL OF FISHERIES AND HYDROBIOLOGY, 10(9) May 2015, Pages: 28-33

Ehsan Aziz et al, 2015

RESEARCH JOURNAL OF FISHERIES AND

HYDROBIOLOGY http://www.aensiweb.com/JASA

© 2015 AENSI Publisher All rights reserved

ISSN:1816-9112

Open Access Journal

Review of Structural Relationship between Salt Domes in Central Zagros with Dena Fault

1Ehsan Aziz, 2Mohsen pourkermani, 3Korus Yazdjerdi, Ali sorbi

ABSTRACT TDena fault is one of the fundamentol and basic structures in central Zagros with a length more

than 130 kilometers. Based on field studies, along this fault at least two salt domes have been recognized, which are referred to in this research as the "Tol Khaki" and "Kouh-e Gol" salt

domes. This fault can be this fault can be divided into two sections including dome (south and

central section) and the section without dome (north section) and these two sections have two completely different processes from one another. In other words, the geometrical property and

the current situation of Dena fault are the result of growth of these two sections in various

periods and ultimately their link to each other. The process of the section including salt domes has been controlled to a large extent by domes which have been aligned linearly.

KEY WORD: Salt Domes, Central Zagros, Dena Fault

1Department of geology, Science

and Research Branch, Islamic Azad university, Tehran, Iran 2Department of geology, Islamic

Azad university, Tehran north Branch,Tehran,Iran 3Department of geology, Islamic

Azad university, Shiraz Branch, Shiraz, Iran 4Department of geology, Islamic

Azad university, karaj Branch, karaj, Iran

Address For Correspondence: Ehsan Aziz, Department of

geology, Science and Research

Branch, Islamic Azad university, Tehran, Iran

Received: 22 November, 2014 Accepted: 28 March, 2015

Published: 12 April, 2015

INTRODUCTION

Tectonic situation:

Zagros Mountain is a series with the length more than 1500 kilometers and 250-400km width which has

been spread from the east of Turkey to Gulf of Oman and it is connected to the Makran subduction zone

(Tavakoli et al 2008). This region of Iran is one the most key regions for studying collisional processes and

development of plateau and associated structures (Sarkarinejad et al, 2008) (figure 1).

Fig. 1: map of topographic bumps and structures and situation of basic fault zones in Zagros fold-thrust belt.

(Sepehr et al, 2006).

29

Dena fault is one of the fundamentol and basic structures in the central Zagros with more than 130km

length. This fault starts from the mountainous areas 25km from northeast of Yasuj and near northern terminals

of Kazerun fault. At first, this fault had a northwest – southeast aligned with the general process of structures in

Zagros which faces a sudden 38-degree clockwise rotation in the rest of the direction and after passing the Dena

Mountain and has an approximately northern-southern extension. This fault, as it gets closer to "Ardal" fault and

high Zagros, faces a change in the process and it gains a northwest – southeast process by dividing to some

branches. This fault gets divided to two branches in its own terminal which transfers a part of deformation and

motion from the Kazerun fault to Ardal fault and "Sabzeh Kuh" by moving toward Kazerun fault and the other

branch find an approximately eastern-western process and moves towards high Zagros Mountains (figure 2).

Fig. 2: map of activated faults in southwest of Iran quoted by Bechmanov et al (2003) (figure A) the situation of

Dena fault in satellite photos SRTM

Mechanism of Dena fault:

This fault contains large components of strike slip in the present age as well based on field observations and

new geodesy measurements (Tavakoli et al, 2008). Based on geodesy measurements, for this fault, Tavakoli et

al (2008) consider more than 13km of horizontol movement. They believe the beginning of the strike slip for

this fault 2.6 to 4.3 millions. This fault has a rate of 3 to 5 millimeters of strike slip in year.

Table 1: rate of horizontol slip of Dena fault and time of the beginning of horizontol quoted by Authemayou et al (2006) and Tavakoli et al

(2008)

fault Totol horizontol

slip

Age of fault onset Average geological

slip rate

GPS derived

slip rate

GPS inferred fault

onset

Dena 13km 2.6-4.3 ma 3-5mm/yr 2.9-4.5mm/yr 2.8-4.5ma

Therefore, we can claim that this fault was a thrust component at first until early Miocene period and after

the collision of Iran and Arabia following the neotethys closure, this fault contained components of strike slip.

In such way that now, the right rotation strike-slip component, this fault is dominant compared to its thrust

components and the performance of the fault in the present day is of the right lateral reverse kind.

Discussion and conclusion:

Among other index properties of stratigraphy in the range which is being reviewed, development of salt

domes are of the Hormoz series in the region. According to the field studies along this fault at least two salt

domes have been recognized, which are referred to in this research as the "Tol Khaki" and "Kouh-e Gel" salt

domes.

Kouh-e Gel dome:

This salt dome is located in the northeast of Sisakht city and alongside with Dena Mountains. This dome

has dimensions of about 1km*2km due to outcrops of igneous rocks together with this dome which are in its

cap. In other words, this dome is about 200 hectares. The existing salt in this dome exits through the existing

30

fountains on the margins of it which fulfills area's needed salt as the economic storages of salt in the area the

conduction of surface waters inside the evaporation ponds and production of salt from them in the past.

Fig. 3: situation of Kuh-e gel salt pond and Dena fault in Zagros belt view toward east

The considerable note in the surroundings of this salt dome is the environmentol embayment which is

created as a result of salt exiting from the salt ponds and the depletion of the lower parts of salt and subsidence

and structural reversion in the area (Aryan, 2011) (figure 4).

Fig. 4: secondary environmentol ponds in periphery of Kuh-e Gel's diapir view to the southTol Khali diapir

This salt dome is located in the Kakan village 25km from the city Yasuj. This dome is located in a 12-km

distance from Mansourkhani village of the villages of Kakan between the geographical latitude 30º38'20’’ to

30º38'20’’ and 51º52' to 51 º 52’10’’ longitudes. This salt dome has an area of 900 hectares. In the location of

the dome and in its west margin, there is a salt pond and the water of this pond demonstrates economic storages

of salt in the evaporative ponds (figure 5).

31

Fig. 5: evaporation pond of salt adjacent to Tol Khali salt dome

Above this salty pond, a fresh water pond flows which is one of the interesting natural phenomena of this

area. Location of this two ponds with their different and opposite natures can most probably be the result of

performance of Dena fault and movement of groundwater and the result of collision of a part of the groundwater

with salt (figure 6).

Fig. 6: situation of salty and fresh water ponds adjacent to Tol Khali salt dome and situation of Dena fault in the

reviewed area

Evolutionary model of salt domes and Dena fault:

Side shortening through undercoat thickening and creation of essential structural bumps for starting the

flotation process lead to rise of salt (Aryan, 2011); this side shortening process is among the compression

structures properties of the earth. Many researchers believe that the start of the salt movement depends on rocky

basis structures (Player, 1969; Edgell, 1996; Hessami et al., 2001). According to this, in the studied area, the

processes of diapirism are probably more affected by the Halotectonic activities than the Hawkins activities;

because as it was specified earlier, the salt domes in the studied area are only seen adjacent to the rocky Dena

fault. This structural relationship creates this belief that the diapirism process in the studied area is in accordance

with the tectonic activities of the base rock. Estimating the starting age of the activity of salt and the length of

diapirism period only based on desert observations is a very difficult act and this is not without a defect by

having hollow seismogram data. By interpreting a large number of seismogram lines of the Persian Gulf and

32

Zagros, it is deducted that the starting point of the movement of Hormoz salt is at the beginning of previous

Paleozoic and it has started in a short time after the end of sedimentation and has continued until now (Jahani et

al, 2009). This fault can be divided into two sections including dome (south and central section) and the section

without dome (north section) and these two sections have two completely different processes from one another.

In other words, the geometrical property and the current situation of Dena fault are the result of growth of these

two sections in various periods and ultimately their link to each other. The process of the section including salt

domes has been controlled to a large extent by domes which have been aligned linearly.

Fig. 7: evolution and growth model of Dena fault in sections containing salt dome

Salt domes of the area are of the thrust supplied by plug type based on Hudec et al (2006). These sheets are

of the type of the advanced thrusts. This type of salty sheets move toward a drifted fault and this movement as a

flowing sheet leads to transmission of its sedimentary cover (Hudec and Jackson, 2006; in Aryan 2011).

REFERENCES

Aryan, Mehran, 2011. Salt tectonics and diapirism, Asar-e Nafis publications

Bachmanov, D.M., V.G. Trifonov, K.H.T. Hessami, A. Kozhurin, P. Ivanova, A. Rogozhin, M. Hademi, F.

Jamali, 2004. Active faults in the Zagros and central Iran, Tectonophysics., 380: 221-241.

Edgell, H.S., 1996. Salt Tectonics in the Persian Gulf basin. In: Alsop, G. L., D. L. Blundell, I. Davison,

(Eds), Salt Tectonics, Geol. Soc. London Spec. Pub., 100: 129-151.

Hubbert, M.K., 1951. Mechanical basis for certain familiar geologic structures. Geological Society of

America Bulletin, 62(4): 355±372.

Hessami, K., 2006. Tectonic history and present-day deformation in the Zagros fold-thrust belt. Acta

Universitatis Upsaliensis. Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and

Technology 700.13 pp. Uppsala. ISBN 91-554-5285-52002.

Hessami, K., H.A. Koyi and C.J. Tolbot, 2001. The significance of strike slip faulting in the basement of

the Zagros fold and thrust belt : J. of Petroleum Geology, 24: 5-28.

Player, R.A., 1969. The Hormuz salt plugs of southern Iran. Ph.D. Thesis, Reading University, p. 300.

Sarkarinejad, K., A. Azizi, 2008. Slip partitioning and inclined dextral transpression along the Zagros

Thrust System, Iran. Journal of Structural Geology, 30 : 116-136.

Sepehr, M. and J.W. Cosgrove, 2004. Structural framework of the Zagros fold- thrust belt, Iran. Marine

and Petroleum Geology, 21 : 829-843.

33

Tavakoli, F., A. Walpersdorf, C.A uthemayou, H.R. Nankali, D. Hatzfeld, M. Tatar, Y. Djamour, F.

Nilforoushan, N. Cotte, 2008. Distribution of the right-lateral strike–slip motion from the Main Recent Fault to

the Kazerun Fault System (Zagros, Iran): Evidence from present-day GPS velocities, Earth and Planetary

Science Letters. August 2008