The record of paleolake sediments in soil catena in the arid steppe, Kyzylkum Desert, Uzbekistan

• Published in: Catena (Giessen) 2024-11, Vol.246, p.108433, Article 108433
• Main Authors: Kabala, Cezary, Gądek, Bogdan, Mętrak, Monika, Szymczak, Karol, Suska-Malawska, Małgorzata
• Format: Article
• Language: English
• Subjects: alkanes; alluvium; archaeology; Arid steppe; bedrock; biomass; catenas; Fluvisols; geochemistry; Gleysols; Gypsisols; hydrology; lakes; Landscape evolution; limestone; Neolithic settlement; organic matter; regolith; shorelines; Soil memory; Solonchacs; Solonchaks; steppes; sterols; texture; Uzbekistan
• ISSN: 0341-8162
• DOI: 10.1016/j.catena.2024.108433

•The Neolithic Kelteminar settlement existed on lacustrine fine-textured sediments.•The concept of a great lake was rejected in favour of small local lake.•Polygenetic soils allowed reconstructing the environmental changes.•Disappearance of the lake led to abandonment of the area by Neolithic stockbreeders.•Gypsisols are underestimated in soil maps of the area in favour of Calcisols. The Neolithic Kelteminar culture developed in Central Asia mainly along the paleochannels of the Zerafshan delta. However, many settlement sites were identified at approximately 200 m a.s.l without a clear relation to known water bodies. The present study aimed to test the hypothesis on the Neolithic settlement on the lacustrine sediments of a postulated great lake, based on a geomorphological and pedological investigation. This investigation was performed at Ayakagytma “The Site”, one of the best documented Kelteminar settlements near the Ayakagytma depression, about 130 km north of Bukhara in the Kyzylkum Desert, Uzbekistan. The investigation was conducted in the catena localised at the transition from the dry-steppe plateau to the bottom of the Ayakagytma Depression. Soil profiles at the archaeological site consist of fine-stratified, fine-textured sediments, free of coarse fragments. The morphology, texture, and geochemistry of the sediments suggest their lacustrine origin and differ substantially from those identified on a high plateau (old, coarse-textured alluvium) and in the depression (stratified, variably textured alluvium and clay-textured regolith, rich in bedrock fragments). The composition of n-alkanes and sterols in the buried A horizons allowed the differentiation between the terrestrial, transitional, and lacustrine origin of biomass and supported the reconstruction of the environmental conditions accompanying the sedimentation of organic matter. The study area has experienced successive climatic and hydrological changes, currently reflected in the unique features of soil sequence starting with relict Gypsisols on the high plateau, Solonchaks (archaeological site in the transitional zone), and Fluvisols and Gleysols in the depression. Favourable conditions for a Neolithic settlement existed along the shoreline of a small lake in the transitional zone between the depression and the plateau. The disappearance of the lake after the destruction of the limestone barrier was the most probable reason for the permanent abandonment of the area by Neolithic stockbreeder