Abstracts of Symposium 55 and some papers from other related Symposia.

Radiocarbon Age of East European Forest-steppe Holocene Paleosols

Alexander L. ALEXANDROVSKY, Institute of Geography, 109017, Moscow, Staromonetny, 29, Russia;
Olga A. CHICHAGOVA, Inst. of Geography, Moscow, Russia.

Sod-Podsolic and Grey Forest soils with relic humus horizons (¹⁴C age of 3000-8000 years BP) are widespread in Holocene Forest-steppe zone. These horizons represent the well-preserved lower part of humus profiles in the Middle Holocene Chernozems and Grey Forest soils degraded under forest vegetation.

The non-degraded and complete soil profiles of the steppe (and/or forest-steppe) stage of soil evolution were found under burial mounds and ramparts of the Neolithic, Bronze and Iron Ages in the same region. We have obtained more than 40 radiocarbon dates of these Holocene Paleosols. The 14C dating of humic acids extracted from the studied soils are as follows. Pre-Carpatian region: Chernozem buried 2350 ±50 BP under rampart: 3420 ±70 - 7650 ±120 BP; background Light Grey Forest soil have relic horizon 5030 ±120 BP. Middle Volga basin, burial mound of XVIII BC: Dark Grey Forest paleosol: 5550 ±150 - 8190 ±90 BP; background Sod-Podsolic soil - 6440 ±190 BP. North Caucasus, burial mound of XXX BC: Buried Chernozem - 6454 ±102 - 9784 ±587 BP; background Grey Forest soil - 7130 ±40 BP.

According to numerous soil and archaeological evidence the completion of the steppe stage of soil evolution and the beginning of the forest stage in the Eastern Europe took place 2500-3000 BP. The age of the middle phase and the beginning of the steppe stage determined by ¹⁴C dating of buried Chernozemic paleosols ranges between 6500-9800 (North Caucasus) and 5900->7600 BP (Pre-Carpatian). The acquired data enables to distinguish two main stages of Holocene soil evolution in the Forest-steppe zone: the steppe stage (BO-SB periods) was succeeded in SA period by the forest stage. Also, the beginning of the AT period (7860 ±100 BP; upper Volga Basin) was marked by the development of the podzolization in soils induced by the cooling of climate and the increase in humidity; however the intensity of this process was much weaker than in the SA period.

Along with relic humus horizons of the BO-SB periods, characterized above, the profiles of Sod-Podzolic soils show the traces of more ancient buried humus at the depth of 70-100 cm and more. The C age of these horizons is about 9810 =?-163 - 10300 ±60 BP. Though renovation processes should be considered. Therefore, the formation of these horizons dates back to the Allered and their cryogenic deformations - to the Young Dryas period.

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