The Role of Neotectonics on Fluvial Systems in the Quaternary Case Study: Rivers of Northern Slope of Misho-Dagh Mountains, Northwest Iran

Misho-Dagh Mountain range is part of Azerbaijan plateau in Northwest Iran. This E-W range is located between Marand and Shabestar plains. Northern Misho fault, the main fault in study area, and other parallel faults have separated the topographic units and geological structures. Rivers on the northern slope of Misho- Dagh, flowing from the south to the north, cut across geological structures and topographical units in their distal reaches, prior to joining in the Marand plain.The long-term drainage evolution and its creation, as transverse fluvial systems, have been examined by reconstruction of drainage network using a combination of geological and geomorphological records. This reconstruction is based on analysis of topographic and geologic maps and area photos and repeated field studies on fluvial remnants. Results show that drainage evolution in the study area has occurred in three stages: a) sedimentation of the Plio-Pleistocene non-compacted conglomerates (relict alluvial fans), b) uplift of the Plio- Pleistocene sediments in mid-? Late Pleistocene, separation of this sediments from main mountainous body of Misho-Dagh due to a E-W synclinal valley, formation of new block of mountains (anticline) in the north of the valley and eastward diversion of rivers in their distal reaches, and c) faulting of new relief block by S-N faults crossing the relief axis, verification of rivers to fault lines and formation of new alluvial fans.Neotectonic indices such as inclination of the Plio- Pleistocene sediments, separation of this sediments from main mountainous body of Misho-Dagh, verification and non-verification of rivers by tectonic and geologic structures, catchment morphometric properties, and situation and morphology of alluvial fans indicate that fluvial systems in the study area are influenced by the Pleistocene and Holocene tectonic activities, and tectonics is the main factor in the fluvial system replacement and their situation.