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Basement Faults and Their Relationships to Salt Plugs in the Arabian Platform in Southern Iran
Discussion:
12 strike slip faults are recognized in the study area (Figure 2). Some of these faults could have important role in forming of pull a part basin for uplift of salt domes. They are as follows:
Fault No. 1: This dextral strike slip fault with 147° azimuth, deviated the axes of Forgun, Neyzeh and Kushkuh anticlines as well as displaced some features and caused linear outcropping of salt plugs specially in Kushkuh.
Fault No. 2: This dextral strike slip fault with 139° azimuth has caused deviation of the axes of Muran, Finu, Baz, Handun and Namak anticlines. The rotation of Muran anticline is an interesting feature of the previous activity of this fault. Several salt plugs are outcropped in this fault’s trend such as Handun and Namak salt plugs.
Fault No. 3: This strike slip fault with 135° azimuth causes deviation in the axes of Gachin, Gashu, Guniz, Muran, Bundasht, Shemilu and Shab anticlines. There are sixe salt plugs such as Anguran in the trend of this fault. Trust faults in Bundasht anticline, probably are formed by this fault.
Fault No. 4: This fault with 135° azimuth has caused right lateral offset of the axes of some of anticlines such as Kuh-e Kohneh, Pishavar, Gach, Burkh, Nakh and Champeh. There are seven salt plugs such as Kermostaj in Gach anticline, Bam and Namakdan in Qeshm island, which are outcropped in the direction of this fault. To the southeast, this fault may cross Tonbe Bozorg salt plug. In Kohneh anticline, it creates some minor faults parallel to itself and some of them to the axis of Kohneh anticline. Because of the activity of the minor faults, recognition of the anticlinal axis is very hard at this part of the anticline. This fault has created some minor faults parallel to itself by crossing Nakh anticline.
Fault No. 5: This dextral strike slip fault has caused deviation of the axes of Bostameh, Champeh, Herang, Nakh, Gavbast and Paskhand anticlines. It also displaced the axis of Nakh anticline and syncline, which is located between Gavbast and Nakh anticlines. This right lateral displacement is very clear in Asmary, Jahrom, Gachsaran and Guri Formation at the northwest limb of Nakh anticline. Exposure of salt domes at the east and northeast of Bastak could be related to this fault’s activity. These are several salt plugs such as Kildun, which are outcropped at the direction of the fault in 140° azimuth. Kildun salt plug has a sharp fault boundary parallel to the fault direction. Cutting of Bakhtiari and Aghajari formations and forming sharp scraps in the salt plugs are also evidence of this fault activity. To the southeast, this fault may cross Tonbe Bozorg salt plug.
Fault No. 6: This strike slip fault in 167° azimuth crosses Chiru salt plug and causes a deviation the axis of some anticlines such as Chiru, Lavarestan, Gavbast (also, there is about 10 km right lateral offset in this anticline axis) and Bavash in right lateral sense of molion. Also, there is some minor faults parallel to the major fault (Fault No. 1) which is formed as the result of this fault activity. These minor faults specially could be seen in the Lavarestan, Gavbast and Bavash anticlines. Existence of erosion and collapse structures parallel to this fault trend, in Gavbast and Bavash anticlines could be related to this fault activity too. Minor faults trend and the pattern of erosion in Gavbast anticline, increase the possibility of a hidden salt plug in this area.
Fault No. 7: This fault with 80° azimuth, has caused deviation of the axes of Bostameh, Ashuru, Champeh, Khamir, Shab, Genow, Guniz, western end of Namak, eastern end of Handun, Neyzeh and eastern end of Furghun. Eight salt plugs outcropped in its trend.
Fault No. 8: This sinistral strike slip fault with 36° azimuth, has a concavity in its trend, to the east. It has deviated Muran, Shab, Iicheh, Champeh and eastern end of shemilu anticline axis. Outcropping of several salt plugs such as Homeiran in the trend of this fault and creating minor faults special in Muran and Ilcheh anticlines, are considerable.
Fault No. 9: This fault with 76° azimuth, causes laterally displacement in the axes of Baz, Shab, Bam, Nakh, Herang, Namaki and Chiru anticlines and crosses in the southwestern part of it to Hendurabi island. Seven salt plugs are outcropped in its trend such as Bam and Shab salt plugs. This fault has created several minor faults special in Baz, Shab, Bam and namaki anticlines. It have deviated the axis of Shab anticline in 60° and has created some clear minor faults there and also outcropping of shab salt plug in this anticline could be related to this fault activity. Five kilometers displacement in the axis of Nakh anticline and creating several minor faults in circular form, maybe resulted to a hidden salt plug there.
Fault No. 10: This sinistral strike slip fault 14° azimuth is concave to the west. It has started in the north from the western end of Dasht-e Kanar and has deviated the axes of Qaleh Shur, eastern end of Chahal, anticlines. Seven salt plugs have outcropped in its trend. Fault controlled edge of a salt plug located in Herang anticline and the minor faults in Bam salt plug are some evidences for this fault activity. This fault may pass Farur Bozorg and Farur Kuchak islands.
Fault No. 11: Deviation in eastern end of Gach anticline axis and also the axes of Burkh, eastern end of Gavbast, eastern end of Gezeh, Kuh-e namaki and Chiru anticline outcropping of seven salt plugs in the trend of this fault, creating of several minor faults specially in Burkh and Gavbast and Sharp cutting of Bakhtiari and Aghajari formations between Gavbast and Gezeh anticlines are some evidences for this sinistral fault with 50° azimuth, which is ended to the northeast to Dasht-e namak anticline.
Fault No. 12: This sinistral strike slip fault with 67° azimuth is started from the eastern end of Kurdeh anticline. It has deviated the axis of some anticlines such as Kurdeh, Gach, west of end of Burkh, Eastern end of Paskhand, Gavbast and Dehnow. Sharp cutting in the east of Kurdeh, linear edge of Kurdeh salt plug, displacement the axis of Gach anticline, clear deviation between Paskhand and Burkh anticlines and outcropping of a salt plug there, forming minor faults specially in Kurdeh, Gach and Dehnow anticlines and outcropping of six salt plugs are some evidences for the activity of this fault.
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