Role of Saravan Thrust Fault on Formation and Development of Saravan Catchment Basin

Development of drainage basins has close relation with geomorphologic and geologic parameters. Therefore, study the relation between structural parameters like faults and development of drainage basins has greatly considered in hydrology and hydrogeology studies. Saravan drainage basin is a perfectly long basin that is extended along Saravan fault. In this survey, the method for studying morphometric and geology indices has been implemented for development of drainage basin. Clearly, present morphology is reflecting the erosion and geological processes particularly in Quaternary age. Saravan drainage basin is in the south-east part of Iran and has developed on flysch of this area. Drainage of Saravan basin joins to Mashkid river and finally leads to Pakistan. Different factors and parameters are important in formation and development of drainage basins including topographic, litho logy and structural factors. One of the important factors in development of this drainage basin is the evolution and activity of Saravan thrust fault. Saravan fault with N135-145 trend has located on the north edge of Quaternary alluvial of the basin. The fault slope is approximately at same direction with flysch layering and slope direction’s is 45-60 degree toward north-east. Saravan catchment basin is a long basin with 5.07 length to width ratio. Prepared maps and profile sections show a clear tilting and asymmetric basin. Morph metric index of tilting of basin (T) is maximum 0.72 and is maximum 0.83 in alluvial basin part. Asymmetric AF index is equal to 62/28 and it is equal 78/74 in the alluvial part. Clear asymmetric of basin and fault position on the north edge basin with average Smf equal to 1.42 showes that Saravan fault has been relatively an active fault. This fault has affected on formation and morphogenesis of Saravan drainage basin during its evolution.Younger northern-southern faults with dextral strike-slip (as Gosht fault) has caused small bent on general trend of alluvial along the drainage basin.