A. Naeimi; M. R. Ghassemi; M. R. Sheikholeslami; A. Hajihosseini
Abstract
The Attary Fault is an oblique fault with a mapped length of ~20 km. It is concealed by Quaternary deposits both northeastward and southwestward. However, there is a fault in the north of Kavir-e-Chah Jam that can be considered as the northeast continuation of the Attary Fault in this area. In addition, ...
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The Attary Fault is an oblique fault with a mapped length of ~20 km. It is concealed by Quaternary deposits both northeastward and southwestward. However, there is a fault in the north of Kavir-e-Chah Jam that can be considered as the northeast continuation of the Attary Fault in this area. In addition, satellite imagery reveals that the Mayamey Fault System extends southwestward into north of the Kavir-e-Chah Jam. Therefore, the Attary Fault may join the Mayamey Fault System in the north of Kavir-e-Chah Jam and hence reach a length of ~127km, considering the concealed parts. There is another major fault with maximum reported uplift of 4km, called the Peyghambaran Fault, to the northwest of the Attary Fault. To the west, the Peyghambaran Fault is linked to the Semnan Fault. The connection of the Attary Fault to the Peyghambaran Fault, Semnan Fault and Mayamey Fault System leads to creation of a greater fault system that could have served as the boundary between Alborz and Central Iran, despite the fact that the Attary Fault does not represent significant uplift and mostly cuts the Eocene volcanics. Additionally, since the Attary fault steeply dips to SSE (60-75◦), the so-called “positive flower structure” which is widely regarded as the general framework for the Central Alborz has not formed in this part of the range. Our study also shows that a left-lateral motion has been initiated on the Attary Fault following the westward motion of the south Caspian basin in the Late Cenozoic.
A Naeimi; Gh Heidarzadeh; M.R Sheikholeslami
Abstract
Geomorphic evidence along the Siah kuh fault (North of Jajarm) shows this fault has been active during Quaternary. Faulted Quaternary deposits, deflected and offset streams and bisected alluvial fans are among such evidence. These together with fault scarps in Neogene and Quaternary strata reveal young ...
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Geomorphic evidence along the Siah kuh fault (North of Jajarm) shows this fault has been active during Quaternary. Faulted Quaternary deposits, deflected and offset streams and bisected alluvial fans are among such evidence. These together with fault scarps in Neogene and Quaternary strata reveal young left-lateral motions on the Siah kuh fault as a part of the Shahrud fault system. However, there are Paleozoic and Mesozoic Formations juxtaposed with Neogene and Quaternary deposits along the fault. Some of these old units have cropped out in northeastern termination and bends along the fault, while others are observed where there is not a bend. Therefore, thrust faulting must have brought them to the surface. Aeromagnetic maps show that Siah kuh fault coincides with an aeromagnetic lineament. Consequently, the geomorphic features suggest only the youngest slips on the fault. Therefore, the Siah Kuh has been a thrust fault whose kinematics change and initiation of left-lateral motions resulted from changes in stress regimes and a regional reorganization during Quaternary.
