Bronze age paleosols in the steppe area of the southern Cis-Urals in solving the problems of paleopedology and archaeology (a case-study of the Tashla IV site in the Orenburg region)

Abstract

The aim of the study. To study the Bronze Age paleosols (Yamnaya and Srubnaya cultures), perform paleoclimatic reconstructions and comparison with previously studied synchronous paleosols in the Cis-Urals steppe. Location and time of the study. The studied site is located in the Orenburg region in the steppe area of the Southern Cis-Urals. In July 2019 and 2021 together with researchers from the archaeological laboratory of the Orenburg Pedagogical University, rescue excavations were carried out at the Tashla IV kurgan cemetery, located near the Tashla village. Kurgans 1 (Yamnaya culture) and 2 (Srubnaya culture) were studied. Methods. A comprehensive morphogenetic analysis of the soils buried beneath the kurgans and surface soils of the studied site was carried out; the soils were described in detail and classified in the field. Soil samples were analyzed for particle size distribution, loss of ignition, pH of the water extraction, content of organic and carbonate carbon, exchangeable bases and magnetic susceptibility. To carry out the paleoclimatic reconstructions, the chronosequence and comparative geographic methods were used. Results. It was established that the studied soils were buried under the kurgans at the beginning of the development of both cultures, when the stages of climatic aridization were close to their ending or ended in the first half of the 4th millennium BC (Yamnaya culture) and at the turn of the 3rd and 2nd millennia BC (Srubnaya culture). The climatic aridization during the Early stage of the Srubnaya culture was more significant than in the Early (Repinsky) stage of the Yamnaya culture, and this conclusion was made for the first time for the studied region. Conclusions. The studied soils properties could be grouped according to the characteristic times of their response to changes in external conditions: magnetic susceptibility, associated with microbiological activity, refers to rapidly changing properties, i.e. in the first decades, whereas changes in other studied properties require from several decades to hundreds of years. Comparison of the Srubnaya paleosol buried under kurgan 2 in the studied site with other soils of the same culture in the region made it possible to place it more accurately on the time scale, attributing to the very beginning of the 18th century BC, and additionally to characterize in detail the climate change within the time span of the Srubnaya culture of the Cis-Urals steppe.