Dating the Dam Lakes Caused by Seymareh Landslide Using Thermoluminescence Methods

Large-scale landslides, especially those that block rivers, are among the most dangerous natural phenomena in mountainous regions all over the world. Occurrence of the world's biggest landslide in the Kabirkuh and on the way of Seymareh and Kashkan rivers blocked rivers and formed Seymareh and Jaydar dam lakes. The aim of this research which is an applied-developmental research and which is conducted using observational, historical and analytical methods is to reconstruct the dam lakes caused by Seymareh landslide occurrence and also to determine the age of them utilizing thermoluminescence techniques in order to determine the date of the occurrence of Seymareh landslide and formation of the lakes. Field studies using physical and conceptual tools together with laboratory methods have led to recognize four staged stalactites slips in the Kabirkuh and the subsequent formation of four lakes in the area of Seymareh valley and a single-stage lake within the Kashkan valley. The findings based on dating of eight samples from the surface and floor of Seymareh and Jaydar lakes using Thermoluminescence shows that the occurrence date of the Seymareh landslide and primary formation of of Seymareh lake is 85000 years ago.
The second Seymareh Lake formed 16500 years ago, the third one formed 10500 years ago and the fourth lake formed 10100 years ago. Therefore, Seymareh Valley has been exposed to consecutive landslides from 85000 to 10000 years ago. Jaydar lake sediments dating suggest that the formation of Jaydar Lake coincided with the occurrence of the main Seymareh landslide in about 85000 years ago and its evacuation in about 5000 years ago. Thus, Jaydar Lake has been lasted for about 80000 years.