Longitudinal changes on grain size and sediments composition in the Baghi River (Northwest of Neyshabur)

Marusk Catchment with an area of 131.87 square kilometers is located in the Northwest of Neyshabur. Baghi River as one of the main tributary of this catchment has been studied with a length of about20.1km.For sedimentological studies a total of 32 sediment samples taken from the active mid-channel of the river that after drying, the granulometry has been analyzed by dry sieving method. After the sample sieving, statistical parameters (median, mean, sorting, skewness and kurtosis) were calculated.3 sedimentary discontinuities have been detected in the sediments of the river. First and second discontinuity is due to input of sediments from the alluvial fan and tributary into the main channel, respectively, and third discontinuity is due to changes in lithology. To determine the percentage of erosion in the formations in this region and determine the amount of sediment yield in each of formations, Abrasion Los Angeles Test is done. Based on this method, Dalichai Formation with according to its lithology and also a great expansion in the region is main formation for sediment yield in this area. In the study area, coarse-grained sedimentary facies (Gmg, Gci), medium-grained sedimentary facies (Sm) and fine-grained sedimentary facies (Fl) were identified. According to sedimentary facies, the architectural elements of SG and FF have been identified. Sedimentary models proposed for this river are including braided gravelly river with sediment gravity flow and shallow braided river with gravel-bed load.