Document Type : Original Research Paper
Authors
1 M.Sc., Department of Geology, Basic Sciences Faculty, Tarbiat Modares University; Geological Survey of Iran, Tehran, Iran
2 M.Sc., Department of Geology, Basic Science Faculty, Islamic Azad University, North Tehran Branch; Geological Survey of Iran, Tehran, Iran
3 Assistant Professor, Research Institute for Earth Sciences, Geological Survey of Iran, Tehran, Iran
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 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.
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