استفاده از روش منشأيابي در تعيين سهم واحدهاي سنگ شناسي حوضه پلدشت در توليد رسوب

Determinining contributions of lithological types of Pouldasht basin to sediment yield using sediment source fingerprinting techniques

Because of the many problems associated with traditional procedures for identifying sediment sources, fingerprinting method, based on physical, chemical and organic properties of sediment and source materials, are increasingly being used as a valuable and effective alternative approach to assembling such information. In this method, a suitable composite (set) of diagnostic properties and a multivariate mixing model are employed to estimate the relative contributions of sediment sources to sediments yield. In this study, using a suitable composite of geochemical elements capable of discriminating subareas underlain by individual lithological types of the study basin and a multivariate mixing model, the contributions of lithological types to sediments yield were determined. The study basin is the main subbasin of Pouldasht water spreading station basin, located in Makoo township, West Azarbaijan province. The lithological subereas were categorized in five groups as sediment sources. Over 106 representative source material samples and 6 sediment samples were collected from lithological groups and sediments deposited in the river bed respectively. Then, the samples were analyzed to determine the concentrations of 18 geochemical elements. 12 out of the 18 geochemical elements were selected as a suitable composite fingerprint using discriminant function analysis. Mean contributions from the lithological subereas of Marl, Conglomerate, Limestone and dolomite, Shale and Slate, and Quaternary sediments were estimated to be 53.9, 29.75, 8.85, 7.5 and 0 percent respectively. Mean absolute error and model efficiency of the method were estimated to be 17.5% and 0.99 respectively. The fingerprinting approach to source ascription is seen as providing valuable information regarding sediment sources in the study basin.