The Last Million Years Recorded at the Loess -
Palaeosol Sequences in the Vojvodina Region, Serbia

Marković, S.B.¹, Hambach, U.², Stevens, T.³, Machalett, B.⁴, Kukla, G.J.⁵,
Oches, E.A.⁶, McCoy, W.D.⁷, Buggle, B.⁸, Gavrilov, M. B.⁹, Gavrilov, M.M.¹⁰, Basarin, B.¹, Zöller, L.²

¹Chair of Physical Geography, Faculty of Sciences, University of Novi Sad, Serbia

²Chair of Geomorphology, University of Bayreuth, D-95440 Bayreuth, Germany

³Department of Geography, Royal Holloway, University of London, Egham, Surrey, TW20 0EX, UK

⁴Humboldt-University of Berlin, Department of Geography, Unter den Linden 6, D-10099 Berlin, Germany

⁵Lamont-Doherty Earth Observatory of Columbia University, Rt. 9W, Palisades NY 10964, USA

⁶Natural and Applied Sciences Department, Bentley College, Jennison Hall 126, 175 Forest Street, Waltham, Massachusetts 02452-4705, USA

⁷Department of Geosciences, University of Massachusetts, Amherst, MA, 01003 USA

⁸Chair of Soil Physics, University of Bayreuth, D-95440 Bayreuth, Germany

⁹Republic Hydrometeorological Service of Serbia, Kneza Višeslava 66, 11000 Belgrade, Serbia

¹⁰Physical Faculty, University of Belgrade, Studentski trg 12, 11000 Belgrade, Serbia

Vojvodina is a region in northern Serbia, located in the southeastern part of the Carpathian (Pannonian) Basin, and encompassing the confluence area of the Danube, Sava, and Tisa rivers. More than 60 % of this lowland area is covered with loess and loess-like sediments. Eolian silt accumulation in Vojvodina began in the late Early Pleistocene. Serbian loess deposits are among the oldest and most complete loess-paleosol sequences in Europe and thus could form the basis of a continental scale stratigraphic scheme that would alleviate much current chronostratigraphic uncertainty and enable more broad-scale climatic reconstructions. As a record of pedogenic alteration, the magnetic susceptibility record provides a means of correlating the sequence with key loess sites in Central and Southeastern Europe, Central Asia, China, and with key climate archives such as the marine oxygen-isotope, pollen variations from lake sediments and deuterium values from Antarctic ice core records on multi-millennial timescales. The completeness and long time frame covered by loess-paleosol sequences in the Vojvodina region is unusual in European loess sequences providing a rare opportunity to investigate detailed and long-term climatic change over the Middle Pleistocene in a region influenced by airmasses originating from high and middle latitudes, as well as the North Atlantic and Mediterranean. The changing relative importance of these air masses through time provides insight into local and regional atmospheric systems and their evolution through the last c. 1 Ma.

The strongly rubified interglacial soils exposed in the youngest Early Pleistocene and older-mid Middle are clearly different from the forest soils of the mid-late Middle Pleistocene and the steppic like interglacial soils of the later Middle and Late Pleistocene. These lowermost soils in the sequence display characteristics associated with sub-tropical soils, in contrast to the temperate forest or steppe environments that appear to have been responsible for the formation of the middle and upper soils. This suggests that there has been a progressive trend towards aridification in the study area. These palaeopedological observations are confirmed by employing quantitative geochemical and grain-size proxies and a soil colour rubification index. This trend to decreased weathering up section in interglacial units contrasts with both the general understanding of global trends in Quaternary climate, as expressed in the marine record and ice core records, and also regional climate proxies from lacustrine archives in south-eastern Europe. The latter of these reconstructions suggest lower amplitude of interglacial climate changes than the succession of interglacials recorded in loess-paleosol sequences of the Vojvodina region. The significant changes in interglacial environments preserved in the Vojvodina’s loess deposits coincide with the occurrence of warmer and shorter post Mid-Bruhnes Event interglacials recorded in EPICA ice core deuterium records. They also correspond to quantitative reconstructions of vegetation change observed in the Tenaghi Philippon pollen record, such as increasing dominance of drought tolerant taxa after MIS 16.

Similar decreases in rubification during the Middle to Late Pleistocene at the Chinese Loess Plateau. If taken as evidence of changing interglacial conditions during the Middle Pleistocene, this highlights the importance of obtaining long-term regional records before conclusions over general climatic trends can be made from more hemispheric/ global archives and suggests that the pattern of long-term climatic development during the Pleistocene is more complicated and regionally variable than is implied by many climatic global archives.

Of additional interest is palaeosol V-S4. This unit correlates with MIS 11, hypothesised to be a potential analogue of Holocene insolation conditions. V-S4 appears to be one of the least developed soils in the profile and is not exceptionally thick, in contrast to what may be expected from the marine record. Further investigation of this soil promises to provide evidence concerning the climatic regime in Eastern central Europe over this crucial interval. A further interesting aspect is the apparent length of time covered by pedocomplex V-S5 and basal red clay complex. These pedocomplexes may represent prolonged but extremely slow loess accumulation during the long interglacial conditions from MIS 13 to MIS 15 and late Early Pleistocene. Strongly developed pedocomplex V-S5 formed during the MIS 13-15 which are expressed as relative cool periods in marine oxygen isotope. Strong developed paedocomplex S5 in Chinese loess also indicate strong summer monsoon conditions in East Asia. Vojvodina region is located at the boundary of a number of different air masses originating from the high and middle latitudes, as well as the maritime Atlantic and Mediterranean. The influence of these air masses will have changed over glacial to interglacial cycles, as well as over the longer term throughout the Pleistocene. Thus, the loess-paleosol sequence in the Vojvodina region can be regarded as a sensitive indicator of the dynamics of continental scale climatic systems, as well as regional climate. This suggests that the trend towards aridification at the Vojvodina region may not only be a local signature, but reflects a reduction in the influence of moisture bearing systems during interglacials over the course of the Middle Pleistocene. According to this hypothesis, decreased humidity during the Pleistocene should be expressed most strongly from the middle Danube Basin to the Black Sea coast where small changes in moisture will be most acutely felt.

Corresponding authors: Slobodan B. Markovic | slobodan.markovic@dgt.uns.ac.rs