Volume 18, Issue 58 (No.3&4-صفحات انگلیسی از 13 تا 73 2004)                   2004, 18(58): 97-114 | Back to browse issues page

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Abstract:   (7202 Views)
Kuhbanan fault is located between Tabas and Yazd blocks in the south west margin of central Iran microplate, extending from North west of Kerman to East of Bafgh, with 300 km length and NW-SE strike. The fault is one of the most seismic structural trend in the region. The latest seismic activity of the fault occurred on the first of April, 2002 with Ms=4,3 over the north-east Dehzo-segment of the fault. Kuhbanan earthquake fault consists of several segments. Movement in the southeast and central segments has been dextral strike-slip with a large reverse component during Plio-Quaternary.Study of alluvial fan deposits in Zarand, Toghroljerd and Bahabad plains indicates that deposition, development and morphology of the alluvial fans have been affected by the tectonic activity of Kuhbanan fault segment and morphology of the alluvial fans have been affected by the tectonic activity of Kuhbanan fault segment which are located in the mountain front of Kerman-Kuhbanan and west Bahabad mountain ranges. Several coalesced alluvial fans exist which are adjacent to Tikdar-Gorcho, Khanok, Rigabad-Daho, Apang-Sarbagh, Gisk, Dartangal, Dehzo and NW Dehzo fault segments in the eastern margin of Zarand plain. The youngest part of the fans is formed in the fanhead area and apex of fans does not progress to the mountain front. Active and inactive areas are formed at the surface of fans some of the them are deeply dissected. Longitudinal profile of the fans is usually segmented and some show a decreasing slope. Vertical profile of the fans is wedge shape, with maximum thickness adjacent to the fault segments and some fans are lense shape. Internal structure of the fans is mostly buried, but imbricated and inset fan also occur Main channel is in the margin or edge of the fans. Fan deposits are poorly sorted, coarsening upward. Apparent neotectonic fractures occurred in Khanok, Sarbagh, Dehzo and NW Dehzo semi-consolidated fan deposits. Several coalesced alluvial fans also exist adjacent to Toghroljard, Abassabad, Dargaz-Godgaz, SE Gavar, Fakhrabad, Khoshabad, Hossinabad and Kuh-e-Sorkh fault segments in the eats margin of Toghroljard plain and in the west margin of the Bagabad plain. Apex of the fans does not progress to the mountain front. Active and inactive areas are formed at the surface of dissected fans. Main channel is in the margin or edge of the fans. Apparent neotectonic fractures occurred in Fakhrabad, Khoshabad and Hossinabad fan deposits. Based on the surface morphology, vertical variation and internal structure of the alluvial fans, it is concluded that 1) neotectonic activity of fault segments have caused continuous elevating of mountain front or sinking of piedmont, and right lateral displacement of mountains relative to plain at late Quaternary. 2) The highest tectonic activity have occurred over Khanok, Righabad, Gisk, Dartangal, Apang-Darbagh, NW Dehzo and Fakhrabad segments during and after deposition of alluvial fans.
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Published: 2004/08/15

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