پديد آورندگان :
رضايي مقدم، محمدحسين نويسنده , , خيريزاده آروق، منصور نويسنده دانشجوي دكتراي ژيومورفولوژي، دانشگاه تبريز , , سرافروزه، سليمان نويسنده دانشجوي دكتراي ژيومورفولوژي، دانشگاه تبريز ,
كليدواژه :
ميشوداغ , شاخص هاي ژيومورفيك , مورفوتكتونيك , نيمرخ تعادل
چكيده فارسي :
در اين پژوهش، دامنه جنوبي ميشوداغ در استان آذربايجان شرقي از نظر فعاليت هاي نيوتكتونيكي مورد بررسي قرار گرفته است. در اين زمينه، مجموعه اي از روش هاي توصيفي، ميداني و تحليلي به كار گرفته شد. براي انجام محاسبات از نقشه هاي توپوگرافي مقياس 1:50000، نقشه هاي زمين شناسي مقياس 1:100000 و تصوير DEM (30متر) منطقه در قالب نرم افزارهاي Arc GIS و اتوكد استفاده شد. در رابطه با هدف تحقيق، سه نوع پارامتر كمّي ژيومورفيك شامل پارامترهاي پنجره اي، پيوسته و گسسته مورد استفاده قرار گرفت. نسبت پهناي چارك ها، نسبت جامي، نسبت مساحت چارك ها و شاخص عدم تقارن حوضه آبريز از مهمترين پارامترهاي حوضه اي تحقيق مي باشند. بخش مهمي از اطلاعات از روي نيمرخ طولي آبراهه هاي اصلي حاصل گرديد. مهمترين اين اطلاعات شامل محاسبات مربوط به نمايه گراديان آبراهه هاي اصلي و نمايه انحراف از نيمرخ مي باشند. شاخص هاي ديگري مانند پيچ و خم جبهه كوهستان و نسبت پهناي كف دره به ارتفاع دره محاسبه شد. همچنين جهت تحليل سه بعدي از منطقه، منحني هاي هيپسومتري واقعي و تيوريك براي هر يك از حوضه هاي مورد مطالعه ترسيم گرديد. درنهايت، براي پي بردن به روند كلي تغييرات شاخص ها، خط مرجعي به طول تقريبي 55 كيلومتر از ابتدا تا انتهاي منطقه مورد مطالعه كشيده شد و مقادير هر يك از شاخص ها نسبت به آن به صورت نمودار ترسيم گرديد. در منطقه مورد مطالعه، مهمترين شواهد جنبش هاي تكتونيك فعّال، وجود پرتگاه هاي گسلي با ارتفاع تقريبي 10 تا 20 متر در امتداد گسل هاي جوان مي باشد. همچنين، وجود پشته هاي مسدود كننده، اسارت رودخانه، بريدگي و تغيير محل رسوب گذاري مخروط افكنه ها در جبهه كوهستان دلايل ديگري بر وجود فعاليت هاي نيوتكتونيكي در منطقه مي باشد. شاخص هاي كمّي ژيومورفيك نتايج مطالعات ميداني را تاييد مي كند به طوريكه، مقادير حداكثر نمايه گراديان طولي و نمايه انحراف از نيمرخ، بيشتر در ارتفاعات پايين تر و تقريبا در نزديكي خروجي حوضه ها قرار دارند كه اين امر را مي توان به جنبش هاي گسل جوان صوفيان- شبستر مرتبط ساخت. نتايج اين شاخص ها به همراه شاخص هاي كمّي حوضه-اي، پيچ و خم جبهه كوهستان، نسبت پهناي كف دره به ارتفاع دره و همچنين تحليل منحني هاي هيپسومتري واقعي و بي بعد نشان دهنده فعّال بودن گسل هاي منطقه مي باشد.
چكيده لاتين :
Introduction
Tectonic geomorphology, broadly defined, is the study of the influence of active tectonism on the landscape. Tectonic geomorphology has two distinct modes of inquiry: the forward problem, in this case the study of the effects of a known tectonic perturbation on the landscape, and the inverse problem, or inferring the nature and relative activity of tectonic elements from observed variation in landscape character. Different researchers in order to investigation of neotectonics and evaluating its effects on the geomorphic characteristics are proposed several rules and indexes. The approach of this research is the application of the quantitative methods for evaluating relative activity of faults in the southern hillslope of Mishow Dagh. Field studies associated with several earthquakes in recent years indicate that faults are active in the study area. The study area, Mishow Dagh Mountain, with geographic coordinates between 38? 05? to 38? 25? N latitudes and 45? 20? to 46? 00? E longitudes is located in eastern Azerbaijan province.
Methodology
For this research, have been used a set of descriptive and analytical methods with field studies. For calculation, we used the topographic maps with scale of 1:50000, geological maps with scale of 1:100000 and DEM images (30m). For this purpose, were used ArcGIS and AutoCAD software. In this study, we used three quantitative geomorphic parameters including window parameters, continuous and discrete parameters. The quartile width ratios, the wineglass ratio, the quartile area ratios and asymmetry index of drainage basins are the most important basin parameters in the research. An important part of the information was obtained from the longitudinal profile of the main stream. In this case, the most important information was included of calculation of the gradient index of main streams and profile deviation index. Other Indices such as sinuosity of mountain front and the valley floor width-valley height ratio were calculated. In order to analyze the three-dimensionally, real and theoretical hypsometry curves for each of the basins were drawn. To understand the overall trend of index changes, a reference line with approximately 55 km length was drawn from beginning to the end of study area, which the values of each index were drawn to it in a diagram.
Results and Discussion
The most important evidence of dynamic and young movements in the study area is the existence of fault scarps along with young faults. Such scarps can clearly be seen with a height of approximately 10 to 20 meters from northern Sharafkhaneh to northern Shabestar. Therefore, geomorphological evidences such as fault scarps, shutter and linear ridges, captivity phenomenon, and cuts of alluvial fans indicate that faults are active in the study area. Quantitative geomorphic indices confirm the results of field studies. Maximum of gradient index are located mainly in the range of 1450 to 2200 meters above sea level. With reference to geological maps and relying on field observations are considered that in this altitude range, are located three major faults with east- west trend. The real profiles of the main streams in some sections are located in the upper of reference or graded profiles, which in most cases, showing uplift along the main stream. Along the reference line, changes trend in the position of maximum deviation on the main stream, are similar the maximum gradient trend.
Conclusion
Indices derived from basin shapes and longitudinal profile of the main streams, particularly the gradient index and profile deviation index, able to represent the evolution of southern hillslope of Mishow Dagh Mountain. So that, both charts of maximums gradient index and profile deviation index shows a clear trend relative to the reference line and in both cases the maximums are located in the elevation ranges of approximately 1500 to 2200 meters above sea level. Also, sinuosity of mountain front index and evaluating cross- valley profiles confirmed these evolutions, and reveals that recent changes are weak or intense evolution likely to belong to the Pleistocene ore early Holocene. Real and theoretical dimensionless hypsometric curves analysis confirms the previous discussion. So that, theoretical hypsometric curves being above in lower parts or in mountain front caused by tectonics. Results from these indices, associated with some of geomorphological evidences such as fault scarps, shutter and linear ridges, captivity phenomenon, and cuts of alluvial fans indicate that neotectonic is active in the southern slopes of Mishow Dagh.
