Progressively cooler, drier interglacials in southern Russia through the Quaternary: Evidence from the Sea of Azov region

Loess-palaeosol exposures along Taganrog Bay, Sea of Azov, in southern Russia, reveal a complex succession of Quaternary palaeoenvironments over the past 0.7 million years. The deposits overlie marine sediments of Tiraspolian (Cromerian) age. At the key section of Semibalki-1, four palaeosol complexes are identified within the series. The earliest palaeosol complex in the Semibalki-1 section is correlated with the late Muchkap Interglacial (the Vorona palaeosol). The soil type resembled modern subtropical Mediterranean region soils. The later Middle Pleistocene palaeosols bear evidence of soil-forming processes typical of various temperate zone environments, with a gradual transition to increasingly cooler, drier conditions. Soils suggesting transitional development between kastenozems and chernozems developed during the Likhvin Interglacial (Inzhavino PC). PC 2 (Kamenka Interglacial) is typified by eluviated Luvic Chernozemic soils, possibly formed under prairie parkland conditions. Finally, the Mikulino Integlacial of the Late Pleistocene (Mezin PC) is represented by chernozems similar to the modern (Holocene) soils of the region, but showing enhanced podzolization and fewer seasonal frost features.A succession of environmental changes has been traced in the study region, from semi-humid subtropical environments at the end of the Early Pleistocene to prairie environments, then to boreal-mild temperate during the Middle Pleistocene, and finally towards landscapes with typical steppe soils in the Late Pleistocene and Holocene. The sequence indicates that moisture supply and temperatures during successive interglacials shifted progressively towards increasingly cooler, somewhat drier climates, influencing soil formation.