كليدواژه :
ليتولوژي , base level , tectonic , terraces , Lithology , پادگانه , قزل اوزن , تكتونيك , سطح اساس , Ghezel Owzan
چكيده فارسي :
بررسي پادگانه هاي رودخانه اي از عمده ترين مباحث مربوط به ژيومورفولوژي رودخانـه اي مي باشد؛ ازاين‌رو به عنوان يكي از لندفرم‌هاي محيط‌هاي آبرفتي و ميراثي از چينه‌شناسي، به‌منظور درك زمان تكتونيكي و آب و هوايي به طور گسترده توسط ژيومورفولوژيست‌ها مورد بررسي قرار مي‌گيرد. رودخانه ي قزل اوزن به عنوان يكي از طويل ترين سيستم هاي رودخانه اي، به عوامل ليتولوژيكي و تكتونيكي به‌خوبي پاسخ داده است. بر اين اساس به كمك نقشه هاي توپوگرافي 1:50000 و زمين شناسي 1:100000 منطقه و استفاده از نرم افزارهاي رايانه اي مانند Arc GIS -Global Mapper و Excel پادگانه هاي اين رودخانه از نظر ليتولوژي به بازه هاي مارني، متبلور و كنگلومرايي و از نظر ليتولوژي و تكتونيك، مسير رودخانه به هشت بازه تقسيم شد و نيمرخ عرضي پادگانه هاي هر بازه، تفسير گرديد. نتايج نشان داد كه از بين ليتولوژي پادگانه هاي قزل اوزن (مارن، متبلور و كنگلومرا) پادگانه هاي مارني نامتقارن تر و پادگانه هاي متبلور، در مناطق فاقد حركات زمين ساختي، متقارن تر هستند. در مناطق فاقد حركات تكتونيكي، يا مناطقي با حركات تكتونيكي يكسان در دو طرف بـستر با ليتولوژي مقاوم، پادگانـه هاي متقارن ايـجاد شـده و در مـكانهايي كه فعاليتهاي تكتونيكي دو طرف بستر يكسان نبوده، يا در بين لايه هاي زمين‌شناسي مارن وجود دارد پادگانه‌هاي نامتقارن شكل‌گرفته‌اند. ليتولوژي مارني كه بيشترين ليتولوژي حوضه را نيز تشكيل داده، بيشترين تاثير را در نامتقارني پادگانه هاي اين رودخانه داشته است. تكتونيك در بازه‌هاي A, C, E, F & H فعال و در بازه‌هاي B, D & G غيرفعال بوده است.
چكيده لاتين :
Introduction
Investigation of river terraces is one of the main issues in the field of river geomorphology. River terraces, as a medium of alluvial landforms and heritage of stratigraphy, are widely investigated by geomorphologists to understand the tectonic and climatic time. The formation of alluvial terraces is primarily the result of tectonic rise alongside the cycling cycles. The edges of a river that is hard and resistant to geology are wall-bound or steep sloping, similar to water-breakers, and limit the number of the steppes to the alluvial terraces; but on the sides with a looser lithology, alluvial terraces are formed with a slight slope. Go up or down to the basin or the sea level changes are accompanied by a change in the slope along the river, creating tectonics alluvial terraces. Ghezel Owzan River, as one of Iranʹs longest river systems, has well responded to lithological and tectonic factors. The Ghezel Ozan Basin is located in the northwest of Iran, and in latitude of 34° 53ʹ 21" to 37 ° to 56ʹ 2" north and longitude is 46 ° 27ʹ 43" to 49 ° 19ʹ 43 "east. The origin of the Ghezel Ozan River is from the heights of Chehel Cheshmeh Kordestan and with a length of more than 550 km, after crossing Zanjan, East Azarbaijan and Ardebil provinces, along with several streams along its path, intersects in the Guilan province with the river Shahroud and enters the reservoir of the Sefidrood Dam.
Methodology
Accordingly, river terraces are lithologically divided into marl, crystallized and conglomerate periods with the help of geological (1/100000) and topographic (1/50000) maps and using computer software such as Arc, GIS, Global Mapper, and Excel. River path is also lithologically and tectonically divided into eight periods and profiles of each period are drawn. In order for the collection of information, we have translated several English articles and examined various internal sources related to the subject matter of the research. With the help of geological maps and field observations of the region, we investigated the effect of tectonics and lithology on topography (symmetric-asymmetric) on alluvial terraces. Using the Global Mapper, the cross-sectional profile was mapped along the riverʹs perpendiculars and analyzed.
Result
Results show that from among the major lithologies of Ghezel Owzan terraces (marl, crystallized, and conglomerate), marl terraces are more asymmetric and crystallized terraces are more symmetric in areas without tectonic movements. Symmetrical terraces are formed in areas without tectonic movements or in areas with the same tectonic movements on both sides with resistant lithology. Asymmetrical terraces are also formed in areas where tectonic movements are not the same on both sides or in areas where there are marls in-between geological layers. Marl lithology, which is the dominant lithology of the basin, has the greatest impact on the asymmetry of terraces on this river. Tectonic has been active in A, C, E, F & H periods and inactive during B, D & G periods.
Discussion and Conclusion
On the bed of the Ghezel Ozan River and major parts of Dyvandra to the Miyaneh, Qareaghaj and the greater part of the province of Tarom, it is overcome with Marl Lithology (Hashtchin to Khalkhal, upper and lower part of Hashtrood and Turkmen Chay, southern provinces of Miyaneh and Zanjan, middle section of Sojas). The conglomerate sediments are the dominant lithology of Qazlazan from Soltaniyeh to Nikpay and the upper of most major branches. The irregular dispersion of lithology and faults in different parts of the Ghezel Ozan River makes it impossible to sequentially divide the alluvial terraces. In resistant lithology, alluvial terraces of symmetrical are formed and in the marl lithology, the slope of the arches of the arches provided the possibility of a deep cut and, with deep erosion and common landslides in the transverse surfaces, low-calorie alluvial terraces is created with low altitude difference. Another factor in the asymmetric of the alluvial terrace is the lithology of the basalt and limestone of the Ghezel Ozan River terrace that act as a barrier and by reducing the river slope and reducing the erosion of the water, the river is forced to move horizontally before the strait, the degradation of the compressive levels has led to asymmetry of the terraces and denser plains.
