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High resolution multi-proxy study of the Zmajevac loess section, Croatia

Introduction: The loess-palaeosol sequence at Zmajevac, Croatia is a valuable high-resolution terrestrial archive of paleoenvironmental changes for the Middle and Upper Pleistocene period. The sequence is about 28 m thick and consists of six loess horizons, intercalated by at least (Galović, 2014) five palaeosols and laminated alluvial sand. First dating results showed that these deposits were formed during the Middle and Late Pleistocene cold stages (Galović et al., 2009) during a climate which was much colder than today (Banak et al., 2016). The cyclicity of the changing climate during that time is reflected in the terrestrial gastropod remains in the investigated deposits (Banak et al., 2012 ; Molnár et al., 2010). Methods and Materials: In this study a high- resolution multidisciplinary study was applied for the loess-palaeosol sequence at Zmajevac. Post-IR IRSL dating was applied to establish a more reliable chronological framework. Grain- size and magnetic susceptibility (MS) measurements were performed in 2 cm resolution to reconstruct some paleoenvironmental proxies like precipitation, wind intensity and direction. Detailed clay mineralogical analyses using the X-ray powder diffraction (XRPD) on random mounts of bulk samples and oriented mounts of the <2 μm fraction, accompanied by heavy mineral analysis of the silty fraction, were performed to determine the provenance of the material as well as their connection to paleoclimate changes. Additionally, carbon and oxygen stable isotope measure-ments (δ13C and δ18O) were performed on gastropod shell samples for detailed insight into paleoprecipitation and paleoclimate conditions. Palynological analyses were performed for paleoecological reconstructions. Statistical modelling of grain size distribution was performed to describe compositional trends in sediments, as well as its relation to MS. Results and Discussions: Dating results reveal intensive sedimentation during the last 300 ka which was five times interrupted by soil forming periods, as LoessFest2017, 08-12October, Gorgan, Iran 33 evidenced by the palaeosols intercalating the loess, the grain size and MS results. The laminated horizon is probably the result of deciduous water activity during the end of the Penultimate Glacial period, probably due to initial climate change. According to the provenance analyses based on heavy minerals associations of the silty fraction, the main sources of the material were predominantly located in the Alpine region and subordinately the Dinaride Ophiolite Zone in Bosnia (Galović, 2016). A greater amount of smectite in the older horizons of loess may indicate a stronger input of local volcanic rocks. Deciduous trees pollen from the loess deposits, suggest the existence of refugee areas in the vicinity during the glacial periods. Redeposited dinocysts indicate erosion of the Miocene basement deposits. Key words: Zmajevac loess section, Croatia, post-IR IRSL dating, grain size, MS, clay minerals, X-ray diffraction, stable isotopes, pollen References Banak, A., Mandic, O., Kovačić, M. and Pavelić, D. (2012) Late Pleistocene climate history of the Baranja loess plateau - evidence from the Zmajevac loess-paleosol section (northeastern Croatia). Geol. Croat. 65: 411–422. Banak, A., Mandic, O., Sprovieri, M., Lirer, F. and Pavelić, D. (2016). Stable isotope data from loess malacofauna: Evidence for climate changes in the Pannonian Basin during the Late Pleistocene. Quat. Int. 415, 15–24. doi:10.1016/j.quaint.2015.10.102. Galović, L. (2016) Sedimentological and mineralogical characteristics of the Pleistocene loess/paleosol sections in the Eastern Croatia. Aeolian Res. 20: 7–23. doi:10.1016/j.aeolia-.2015.10.007. Galović, L., (2014) Geochemical archive in the three loess/paleosol sections in the Eastern Croatia: Zmajevac I, Zmajevac and Erdut. Aeolian Res. 15: 113–132. doi:10.1016/- j.aeolia.2014.07.004 Galović, L., Frechen, M., Halamić, J., Durn, G. and Romić, M. (2009) Loess chronostrati-graphy in Eastern Croatia—A luminescence dating approach. Quat. Int. 198: 85–97. Doi-:10.1016/j.quaint.2008.02.004 Molnár, D., Hupuczi, J., Galović, L. and Sümegi, P. (2010) Preliminary malacological invest-igation on the loess profile at Zmajevac, Croatia. Cent. Eur. J. Geosci. 2, 52– 56. Doi-:10.2478/v10085-009- 0045-0.

Zmajevac loess section, Croatia, post-IR IRSL dating, grain size, MS, clay minerals, X-ray diffraction, stable isotopes, pollen

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