ارزیابی فعالیت‌های نوزمین‌ساختی با استفاده از شاخص‌های ژئومورفیک ( مطالعه موردی : شمال غرب تاقدیس کبیرکوه)

نویسندگان

1 دانشگاه طبرستان چالوس

2 دانشگاه شهید بهشتی

چکیده

تاقدیس کبیر کوه یکی از مهم‌ترین ارتفاعات زاگرس چین‌خورده بوده و بررسی سابقه لرزه‌خیزی و همچنین شواهد ژئومورفولوژیکی حاکی از ادامه حرکات نو زمین‌ساخت در این منطقه می‌باشد. با توجه به‌واقع شدن منطقه در زون زاگرس به‌عنوان لرزه‌خیزترین زون ساختمانی کشور و ادامه حرکات زمین‌ساختی در آن ،ارزیابی فعالیت‌های نوزمین‌ساختی جهت شناخت این نوع فعالیت‌ها در منطقه ضروری می‌باشد. هدف از این پژوهش ارزیابی فعالیت‌های نوزمین‌ساختی تاقدیس کبیر کوه با استفاده از شاخص‌های ژئومورفیک می‌باشد. در این راستا از شاخص‌های ژئومورفیک، انتگرال هیپسومتریک (Hi)، شاخص منحنی هیپسومتریک(Hc)، شاخص سینوسیته جبهه کوهستان(Smf)، شاخص نسبت پهنای کف دره به عمق (Vf)، شاخص گرادیان طولی رودخانه (Sl)، شاخص عدم تقارن حوضه زهکشی (Af) و شاخص واحد(Iat) استفاده گردید. نتایج تحقیق نشان می‌دهد که منطقه موردمطالعه ازلحاظ فعالیت نو زمین‌ساخت به سه بخش جنوب شرقی با فعالیت نو زمین‌ساخت شدید، دامنه غربی و قسمت‌هایی از دامنه شرقی با  فعالیت نوزمین‌ساختی متوسط و بخش سوم که در منطقه پراکندگی دارد، با فعالیت نوزمین‌ساختی کم تقسیم می‌شود. مقادیر شاخص­های ژئومورفیک و شواهد ژئومورفولوژیکی حاکی از فعال بودن حرکات نوزمین‌ساختی در بخش‌های از منطقه است. تنوع لیتولوژیکی، وقوع زمین‌لغزش‌ها و دره‌های کارستی بر میزان کمی شاخص‌های ژئومورفیک مؤثر بوده و درنهایت می‌توان گفت که حرکات نوزمین‌ساختی در قسمت‌های مختلف منطقه دارای شدت و ضعف بوده و در کل منطقه داری حرکات نو زمین‌ساخت متوسط می‌باشد.

کلیدواژه‌ها


عنوان مقاله [English]

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

چکیده [English]

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.
 
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.

کلیدواژه‌ها [English]

  • Neotectonics
  • geomorphic indicators
  • Ilam
  • Kabirkuh Anticline