Iron mineralogical proxies and Quaternary climate change in SE-European loess-paleosol sequences

The loess-paleosol sequences Batajnica/Stari Slankamen (Serbia) and Mircea Voda (Romania) represent key archives for the climate and landscape development of the middle and lower Danube Basin during the last 700,000 years. For deciphering the Quaternary climate evolution in these regions, the Batajnica/Stari Slankamen and Mircea Voda sites are for the first time studied by a multi-proxy approach based on iron mineralogical parameters. Changes in the iron mineralogical composition are identified and characterized by rock magnetic investigations, diffuse reflectance spectroscopy (DRS) and Munsell color based proxies. The results show that environmental conditions during mid- and early Middle Pleistocene interglacials were more favorable for hematite formation, suggesting a more oxidizing pedoclimate as in the more recent interglacials. This is also reflected in a gradual increase of the anhysteretic remanent magnetization vs. saturation isothermal remanent magnetization (ARM/SIRM) ratio. In the studied profiles changes in this ratio can be linked to a preferential hematitization of coarse-grained ferrimagnetica and relates to warmer climate conditions and a more extended estival dry period. At the same time, rock magnetic parameters indicate a preferential destruction of fine-grained magnetic particles in older paleosols resulting from seasonal excess moisture. A progressive cooling and decrease of rainfall during the Middle and Late Pleistocene is evidenced not only for interglacial pedocomplexes but also for glacial loess layers. This finding is in line with previously published proxy records of silicate weathering and clay formation at these sites and similar trends reported from other sites in the European steppe belt. Relating iron mineralogical proxies to paleopedological characteristics and proxies of silicate weathering, additionally a change in the seasonal pattern of the interglacial temperature and precipitation regime from a Mediterranean type to a steppe type climate is revealed, highlighting the potential of such a multi-proxy approach. Possible triggers for this paleoenvironmental evolution are discussed, as well, finally highlighting a "Quaternary uplift hypothesis", which best could explain the inferred trend of cooling, aridification and increasing continentality. Accordingly, changes in atmospheric circulation and rain shadow effects induced by small-scale uplift of European mountain belts (Alps, Carpathians, Dinaric Alps) would provide a driving mechanism for the westward extension of the Eurasian steppe belt into Central and SE-Europe during the Quaternary. (C) 2013 Elsevier B.V. All rights reserved.