Revisiting Late Pleistocene Loess–Paleosol Sequences in the Azov Sea Region of Russia: Chronostratigraphy and Paleoenvironmental Record

Jie Chen,Redzhep Kurbanov,Gennady Matishov,Thomas Stevens,Biao Zeng,Taibao Yang,Peihong Shi,Evgeny Konstantinov,Mingrui Qiang

doi:10.3389/feart.2021.808157

Abstract

Loess-paleosol sequences are the most intensively studied terrestrial archives used for the reconstruction of Late Pleistocene environmental and climatic changes in the Azov Sea region, southwest Russia. Here we present a refined chronostratigraphy and a multiproxy record of Late Pleistocene environmental dynamics of the most complete and representative loess–paleosol sequences (Beglitsa and Chumbur-Kosa sections) from the Azov Sea region. We propose a new chronostratigraphy following the Chinese and Danubean loess stratigraphic models that refines the subdivision of the Last Interglacial paleosol (S1) complex in two Azov Sea sites, resolve the uncertainty of the stratigraphic position of the weakly developed paleosol (L1SSm) in Beglitsa section, and allow for direct correlation of the Azov Sea sections with those in the Danube Basin and the Chinese Loess Plateau. More importantly, it may serve as a basis for better constraining local and regional chronostratigraphic correlations, and facilitate the interpretation of climatic connections and possible forcing mechanisms responsible for the climatic trends in the region. In addition, a general succession of environmental dynamics is reconstructed from these two vital sections, which is broadly consistent with other loess records in the Dnieper Lowland and Lower Danube Basin, demonstrating similar climatic trends at Glacial–Interglacial time scales. Furthermore, our results have important implications for the chronostratigraphic representativeness of Beglitsa as a key regional loess section and for the reconstruction of the temporal and spatial evolution of Late Pleistocene climate in the Azov Sea region.

Highlights

The loess–paleosol sequences (LPSs) of the Azov Sea in Eastern Europe–Western Russia are extensively distributed terrestrial deposits that preserve detailed evidence of past climatic and environmental changes in the region
The initial results showed that the whole ~11 m of the Beglitsa section formed since marine isotope stage (MIS) 5 (Chen et al, 2018a), while only the upper ~5 m of the Chumbur-Kosa section corresponds to the same period (Chen et al, 2018b)
There are some stratigraphic paleosols that are visually discriminated in the field, while χlf and χhf do not significantly increase, such as depth intervals of 9.0–8.3 and 4.5–3.2 m of the Beglitsa section (Figure 2)

Summary

Introduction

The loess–paleosol sequences (LPSs) of the Azov Sea in Eastern Europe–Western Russia are extensively distributed terrestrial deposits that preserve detailed evidence of past climatic and environmental changes in the region. Unlike the more uniform LPS further west in central Europe and further east in central Asia, Azov loess deposits and underlying alluvial/marine sediments contain small mammal faunas that are typically distributed along the Azov Sea shorelines, providing an important marker for biostratigraphic correlation between the continental and marine deposits (Dodonov et al, 2000; Dodonov et al, 2006) These fossil assemblages are a vital advantage for the establishment of loess chronostratigraphy (Tesakov et al, 2007). The latter approach of using magnetic variation in stratigraphic correlation is widely applied elsewhere in Europe, such as the Danube Basin region (Buggle et al, 2009; Fitzsimmons et al, 2012; Marković et al, 2015; Sümegi et al, 2018) and the East European Plain (Rutter et al, 2003; Velichko et al, 2006; Hlavatskyi and Bakhmutov, 2020)

Objectives

Methods

Results

Conclusion