Effective physico-chemical indices on marls sediment yield in Zagros structural zone, case study: Chaharmahal and Bakhtiari Province

Marls are one of the main causes of sediment production and subsequent soil erosion in watersheds. Researchs shows that there is a close relationship between the rate of marls sediment yield and their physical and chemical characteristics. With the aim of determining the expansion of marly formations and a quantitative assessment of  the mentioned indices role on the sediment yield of marls in Chaharmahal and Bakhtiari Province, a comprehensive study was conducted and its outstanding results are presented in this study. After identifying and separating the marly formations in Chaharmahal and Bakhtiari Province and performing systematic sampling, necessary physical and chemical experiments were performed and the results were analyzed using statistical methods. Then, using a rainfall simulator, the sediment production rate of each marly stratigraphic units was measured in the field. Results showed that about 1073.95 Km2 (equal to 6.5%) of province rocks has devoted to marly lithological units. On the basis of analyses, Razak, Pabdeh, Hormoz, Mishan and Gurpi formations with mean of 96.34, 94.41, 87.1, 76.17 and 33 grm-2 are the most sensitive marly formations, respectively. Sediment yield is directly related to silt amounts, total lime, active lime, exchangable sodium and reverse related to clay amounts. The presence of Kaolinite and Illite clay minerals is one of the intensifying factors in sedimen yeild in marly formations.