ارزيابي فعاليت هاي نوزمين ساختي با استفاده از شاخص هاي ژيومورفيك ( مطالعه موردي : شمالغرب تاقديس كبيركوه)

Evaluation activities Neotectonics using geomorphic indicators (case study: Northwest Kabirkuh anticline)

تاقديس كبير كوه يكي از مهمترين ارتفاعات زاگرس چين خورده بوده و بررسي سابقه لرزه خيزي و همچنين شواهد ژيومورفولوژيكي حاكي از ادامه حركات نوزمين ساخت در اين منطقه مي باشد. با توجه به واقع شدن منطقه در زون زاگرس به عنوان لرزه خيزترين زون ساختماني كشور و ادامه حركات زمين ساختي در آن ،ارزيابي فعاليت هاي نوزمين ساختي جهت شناخت اين نوع فعاليت‌ها در منطقه ضروري مي باشد. هدف از اين پژوهش ارزيابي فعاليت هاي نوزمين ساختي تاقديس كبير كوه با استفاده از شاخص هاي ژيومورفيك مي باشد. در اين راستا از شاخص‌هاي ژيومورفيك، انتگرال هيپسومتريك (Hi)، شاخص منحني هيپسومتريك(Hc)، شاخص سينوسيته جبهه كوهستان(Smf)، شاخص نسبت پهناي كف دره به عمق (Vf)، شاخص گراديان طولي رودخانه (Sl)، شاخص عدم تقارن حوضه زهكشي (Af) و شاخص واحد(Iat) استفاده گرديد. نتايج تحقيق نشان مي دهد كه منطقه مورد مطالعه از لحاظ فعاليت نوزمين ساخت به سه بخش جنوب شرقي با فعاليت نوزمين ساخت شديد، دامنه غربي و قسمت هايي از دامنه شرقي با فعاليت نوزمين ساختي متوسط و بخش سوم كه در منطقه پراكندگي دارد، با فعاليت نوزمين ساختي كم تقسيم مي شود. مقادير شاخص هاي ژيومورفيك و شواهد ژيومورفولوژيكي حاكي از فعال بودن حركات نوزمين ساختي در بخش هاي از منطقه است. تنوع ليتولوژيكي، وقوع زمين لغزش ها و دره هاي كارستي بر ميزان كمي شاخص هاي ژيومورفيك موثر بوده و در نهايت مي توان گفت كه حركات نوزمين ساختي در قسمت هاي مختلف منطقه داراي شدت و ضعف بوده و در كل منطقه داري حركات نوزمين ساخت متوسط مي باشد.

Introduction Tectonic geomorphology of the study Landform affected by tectonic activity formed and evolved deals. Landform in tectonically active regions, the result of a complex combination of vertical and horizontal movements of crustal blocks and erosion or deposition by surface processes are (Ioannis et al. 2006, p. 211). Geomorphic indicators and geomorphic evidence for the relative simplicity of calculation, speed up the application, extract the required data from topographic maps, aerial photographs, and satellite and desired results are of great importance in studies Neotectonics. Zagros is active on the activities Neotectonics Mirzayi study (1997), more than 50% of the recorded earthquake occurred in Iran in the Zagros region and this region seismically active zone of the building. According to the study of seismic activity in the Zagros Neotectonics and enabled it vital to understand the situation in this zone is Neotectonics in each region. The purpose of this study was to evaluate the activities of Neotectonics using geomorphic indicators are in Kabirkuh anticline. Materials and methods The low values obtained from the geomorphic characteristics (Hc, Smf, Vf, Hi, Af, SL) and field investigation Geomorphologically Geomorphic is used by the Neotectonics. To increase accuracy, the area was divided into 46 sub-basins and sub-basins of the items for each separate calculation. After the transfer layers of digital geographic information system (GIS) parameters were calculated. The hypsometric curve (Hi), the software MATLAB, was used. Then by using the quantitative data obtained from the IAT and geomorphic indicators of activity and the results of the study area Neotectonics geomorphic data were compared with Geomorphic. Results SL index assessment indicates that there are three classes Kabirkooh anticline tectonic activity and accordingly answer the eastern anticline with low activity Neotectonics and other parts of the anticline has a moderate and vigorous activity are. Hypsometric integral index values obtained between 0.2 to 0.96 which may ultimately revealed the presence of three tectonic class in the region Which is much lower than 0.5 and represents the topography of the area studied is old and mature. . The role of mass movements and water erosion, especially in karst valleys and low levels of these indicators is obvious. According Af Kabirkooh anticline 13 sub-basins in the class (1), 16 sub-basins in the class (2) and 17 sub-basins in class (3) are located. The index is the average Neotectonics plays. Vf index between 0.13 to 0.86, which varies in different lithology of this difference can be attributed valleys. Smf values obtained for the studied mountain fronts between 1.27 to 2.07 and the existence of two classes of active and less active to quiet Neotectonics (classes 2 and 3 tectonic) in the region. According to calculations based on IAT study area in terms of Neotectonics combination of three classes 3,2 and 4 Neotectonics activities that represent high, medium and low. There Geomorphologically as triangular surfaces, absence of foothills and deep valleys, alluvial fans fractionated, terraced terraces and floodplains in the formation of new terraces and vertical walls dominate the riverbeds indicates active movements Neotectonic indices manufacturing in the region. Conclusion Values obtained from geomorphic characteristics and classify them according to the IAT index shows that the study area is divided into three parts of activity Neotectonics out. The Southeast region in the east, with younger topography and Neotectonics activity is high. The second part consists of the western and eastern parts of the active medium is Neotectonics. The third part, which is scattered in the area occupied 15% of the total area, Neotectonics activity is low. Geomorphic also confirms the results of the geomorphic indicators. Finally, a summary of results indicators and geomorphic evidence and consideration of geomorphology and Lithology of the region It can be said that Neotectonics movements in different parts of the region has a total area of strength and weakness and Neotectonics-moving average.