Quaternary basin formation in the hanging-wall of North Alborz fault, central Alborz
|Category||Tectonic & Seismotectonic|
|Location||The 3 Symposium of Geosciences|
|Author||Mohammad Reza Ghassemi۱, Niels Hovius۲ and Mahnaz Rezaeian|
|Holding Date||31 July 2007|
The North Alborz fault is a major active fault of the Alborz range. Structural activity in the hanging wall of the fault has resulted in development of small lake and fluvial-lacustrine basins in the central part of the Alborz range. Most of these faults developed in Quaternary time, and are inactive now; however, one of them is still active. From the east to west these basins are Kojoor, Lashak, Zanoos, Dasht-e-Nazir, Marzan-Abad, and Kelar-Dasht basins. The small active Valasht lake may be added to these basins. Sediment fill of the basins may be divided into an older and a younger series. The older series are generally coarse-grained, and are probably related to fluvial-lacustrine environment, while the younger series is generally fine-grained, shows regular bedding, and belongs to lacustrine environment. Both series are deformed in vicinity of the active faults. Structural studies in the area between Kojoor and Kelar-Dasht indicate that these basins are produced as results of recent activity of North Alborz fault, and rapid uplift in its hanging-wall. Backthrusts in the hanging-wall developed gradual barrier against the northward flow of rivers, and sudden activities, such as major landslides, caused total closure of the rivers and development of small lakes.