The age of deposition of accumulative fan sediments in Serteyka River Valley (Western Russia)
Keywords:Geochronology, Little Ice Age, Human impact, Agrotechnical activity, Hillslope processes
AbstractIn the region of the Serteyka River, an extensive accumulative fan was studied. The main goal of the research is an attempt to reconstruct the palaeogeographic development of erosive cuts in Western Russia. The geological structure of the fan and its surroundings was recognized. The fan is built by deluvium sediments, which can be divided into: lower diluvium unit, middle diluvium unit and upper diluvium unit. The top of the fan is built by tillage diamicton. The fan was formed at the earliest from the 2nd half of the 17th century (during the Little Ice Age pessimum). Samples were taken for AMS, OSL, Pb210 dating to determine the phases of fans development. The AMS dating produced mixed results. This was due to the redeposition of the material. Using the OSL method, two samples were dated from the bottom of the clastic fan deposits. Dates from the Neolithic period were obtained, additionally in inversion. It was caused by inaccurate bleaching of the quartz grains. The top part of the fan was dated using the Pb210 method. Slope sediments can be extremely difficult to dating. This may be due to the redeposition of the material, the presence of hiatuses and inaccurate bleaching of samples. The individual units of deluvium sediments differ in colour, structural and textural features.
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