Stages of loess accumulation of the multilayer Kulbulak Palaeolithic site (Uzbekistan)

The multilayered Paleolithic site of Kulbulak is of great interest for the reconstruction of the stages ofhuman settlement in Central Asia (Vandenberghe et al, ۲۰۱۴). The location of the site, the complex structureof the section of Quaternary deposits, numerous traces of mudflow activity, and the lack of absolute datingdata for the lower horizons complicate the task of developing a geochronological scheme for the formationof deposits and determining the age of cultural horizons. Therefore, we have attempted to characterize thesediments of the lower part of the section, in order to distinguish the main stages in the development of thetopography and the natural environment in the area of the camp. During the fieldwork, we made a facieslithologicaldescription of the horizons in the lower half of the section (layers ۱۰-۲۵). Particular attentionwas paid to the characterisation of layer boundaries and the identification of erosion traces. In order tocomprehensively characterise the sediments, samples were selected for luminescence dating, grain sizeanalyses, morphology of sand-size grains, mineralogical composition of the sediments and palynologicalstudies. The geomorphological position of the site has been described and the main factors of modernsedimentation processes have been identified. Based on the analysis of lithological properties andluminescent dating obtained earlier, the chronostratigraphic subdivision of the section was carried out. Thefield studies and analysis of published materials allowed us to identify the main types of relief andcharacterize the leading relief-forming processes. Based on these materials, a geomorphological schemeand a geological-geomorphological profile were compiled. To determine the absolute age of the lower partof the section, the thermoluminescence (TL) dating method was applied. Five samples from layers ۱۱-۱۸were collected in light-tight tubes. Luminescence dating was carried out according to the standardmethodology (Fedorowicz, ۲۰۰۶). The section of the site reveals a complexly constructed sequence ofQuaternary deposits, reflecting the development of the landscapes and climate of the region since the lateMiddle Pleistocene. Based on the generalization of data on the paleogeographic history of the region andcharacterization of exogenic processes, the main factors of relief and sedimentation transformation wereidentified. In the studied part of the section (layers ۱۰-۲۵) ۴ stages of sedimentation are distinguished.Based on the analysis of lithological properties and luminescence dating obtained earlier, achronostratigraphic subdivision of the section was carried out. The results of the study made it possible tocorrelate the time of formation of layer ۲۴ with the warming phase of the second half of MIS ۷, layer ۲۳with the beginning of MIS ۵, layers ۱۶-۱۲.۲-۱۲.۴ (loess) reflect active dynamics of the natural environmentduring the MIS ۵, and layers ۱۲.۱-۱۰ (loess) with MIS ۴. The study was supported by the RussianFoundation for Basic Research, grant no. ۱۹-۰۹-۰۰۴۵۳.

Keywords:

Central Asia , Uzbekistan loess , Late Quaternary , Late Palaeolothic , TL dating