Differences in the reconstructions of the depositional environment of overbank sediments performed using the C/M diagram and cumulative curve analyses

Abstract

In order to compare the results of the reconstructions of depositional environment of sediments performed using the C/M diagram (Passega, Byramjee 1969) and the cumulative curve analysis (Visher 1969), 49 samples of overbank sediment were collected in the valley of the Dunajec River. The samples were collected from the fill of an abandoned channel on the floodplain of the lower Dunajec (17 km from its mouth) and from the floodplain of the Dunajec in the backwater of the Czorsztyn Reservoir and analysed used the laser diffraction and sieve methods. A cumulative curve analysis of the samples located in the fields of dominant deposition from traction in the C/M diagram (Fields I, II, III, IX) showed that the dominant type of their transport prior to deposition was saltation and suspension (81%), while traction amounted to an average of 19%. In the fields of the C/M diagram corresponding to the deposition of graded suspension under the conditions of high (Field IV) and moderate turbulence (Field V), the dominant type of sediment transport before deposition was saltation, whose amounted to 78–86% (Field IV) and 50–76 % (Field V). In the fields of the C/M diagram indicating deposition from graded suspension transported in conditions of low turbulence (VI) and uniform suspension of varied grain size (VII), the dominant type of transport prior to deposition was suspension, amounting to 35–94%. Sediments located in the field of the C/M diagram corresponding to the finest uniform suspension and pelagic suspension (Field VIII) were in 91–95% transported in suspension prior to deposition.